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1. Hetero-antagonism of avibactam and sulbactam with cefiderocol in carbapenem-resistant Acinetobacter spp.

Author: Olivia Wong, Vyanka Mezcord, Christina Lopez, German Matias Traglia, Fernando Pasteran, Marisel R. Tuttobene, Alejandra Corso, Marcelo E. Tolmasky, Robert A. Bonomo, and María Soledad Ramirez
Subjects: Acinetobacter, antagonism, cefiderocol, antimicrobial susceptibility testing (AST), avibactam, sulbactam, Microbiology, QR1-502
Abstract: ABSTRACT Cefiderocol, a siderophore-cephalosporine conjugate antibiotic, shows promise as a therapeutic option for carbapenem-resistant (CR) Acinetobacter infections. While resistance has already been reported in A. baumannii, combination therapies with avibactam or sulbactam reduce MICs of cefiderocol, extending its efficacy. However, careful consideration is necessary when using these combinations. In our experiments, exposure of A. baumannii and A. lwoffii to cefiderocol and sulbactam or avibactam led to the selection of cefiderocol-resistant strains. Three of those were subjected to whole genome sequencing and transcriptomic analysis. The strains all possessed synonymous and non-synonymous substitutions and short deletions. The most significant mutations affected efflux pumps, transcriptional regulators, and iron homeostasis genes. Transcriptomics showed significant alterations in expression levels of outer membrane proteins, iron homeostasis, and β-lactamases, suggesting adaptive responses to selective pressure. This study underscores the importance of carefully assessing drug synergies, as they may inadvertently foster the selection of resistant variants and complicate the management of CR Acinetobacter infections.IMPORTANCEThe emergence of carbapenem-resistant Acinetobacter strains as a serious global health threat underscores the urgent need for effective treatment options. Although few drugs show promise against CR Acinetobacter infections, resistance to both drugs has been reported. In this study, the molecular characterization of spontaneous cefiderocol-resistant variants, a CR A. baumannii strain with antagonism to sulbactam, and an A. lwoffii strain with antagonism to avibactam, provides valuable insights into the mechanisms of resistance to cefiderocol. Some mechanisms observed are associated with mutations affecting efflux pumps, regulators, and iron homeostasis genes. These findings highlight the importance of understanding resistance mechanisms to optimize treatment options. They also emphasize the importance of early evaluation of drug synergies to address the challenges of antimicrobial resistance in Acinetobacter infections.
Published: 2024
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2. KPC-2 allelic variants in Klebsiella pneumoniae isolates resistant to ceftazidime-avibactam from Argentina: blaKPC-80, blaKPC-81, blaKPC-96 and blaKPC-97

Author: María Belén Sanz, Fernando Pasteran, Juan Manuel de Mendieta, Florencia Brunetti, Ezequiel Albornoz, Melina Rapoport, Celeste Lucero, Laura Errecalde, Maria Rosa Nuñez, Renata Monge, Magdalena Pennini, Pablo Power, Alejandra Corso, and Sonia A. Gomez
Subjects: ceftazidime/avibactam, KPC, Klebsiella pneumoniae, allelic variant, Microbiology, QR1-502
Abstract: ABSTRACTCeftazidime-avibactam (CZA) therapy has significantly improved survival rates for patients infected by carbapenem-resistant bacteria, including KPC producers. However, resistance to CZA is a growing concern, attributed to multiple mechanisms. In this study, we characterized four clinical CZA-resistant Klebsiella pneumoniae isolates obtained between July 2019 and December 2020. These isolates expressed novel allelic variants of blaKPC-2 resulting from changes in hotspots of the mature protein, particularly in loops surrounding the active site of KPC. Notably, KPC-80 had an K269_D270insPNK mutation near the Lys270-loop, KPC-81 had a del_I173 mutation within the Ω-loop, KPC-96 showed a Y241N substitution within the Val240-loop and KPC-97 had an V277_I278insNSEAV mutation within the Lys270-loop. Three of the four isolates exhibited low-level resistance to imipenem (4 µg/mL), while all remained susceptible to meropenem. Avibactam and relebactam effectively restored carbapenem susceptibility in resistant isolates. Cloning mutant blaKPC genes into pMBLe increased imipenem MICs in recipient Escherichia coli TOP10 for blaKPC-80, blaKPC-96, and blaKPC-97 by two dilutions; again, these MICs were restored by avibactam and relebactam. Frameshift mutations disrupted ompK35 in three isolates. Additional resistance genes, including blaTEM-1, blaOXA-18 and blaOXA-1, were also identified. Interestingly, three isolates belonged to clonal complex 11 (ST258 and ST11) and one to ST629. This study highlights the emergence of CZA resistance including unique allelic variants of blaKPC-2 and impermeability. Comprehensive epidemiological surveillance and in-depth molecular studies are imperative for understanding and monitoring these complex resistance mechanisms, crucial for effective antimicrobial treatment strategies.IMPORTANCEThe emergence of ceftazidime-avibactam (CZA) resistance poses a significant threat to the efficacy of this life-saving therapy against carbapenem-resistant bacteria, particularly Klebsiella pneumoniae-producing KPC enzymes. This study investigates four clinical isolates exhibiting resistance to CZA, revealing novel allelic variants of the key resistance gene, blaKPC-2. The mutations identified in hotspots surrounding the active site of KPC, such as K269_D270insPNK, del_I173, Y241N and V277_I278insNSEAV, prove the adaptability of these pathogens. Intriguingly, low-level resistance to imipenem and disruptions in porin genes were observed, emphasizing the complexity of the resistance mechanisms. Interestingly, three of four isolates belonged to clonal complex 11. This research not only sheds light on the clinical significance of CZA resistance but also shows the urgency for comprehensive surveillance and molecular studies to inform effective antimicrobial treatment strategies in the face of evolving bacterial resistance.
Published: 2024
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3. Co-integrate Col3m bla NDM-1-harboring plasmids in clinical Providencia rettgeri isolates from Argentina

Author: Denise De Belder, Florencia Martino, Nathalie Tijet, Roberto G. Melano, Diego Faccone, Juan Manuel De Mendieta, Melina Rapoport, Ezequiel Albornoz, Alejandro Petroni, Ezequiel Tuduri, Laura Derdoy, Sandra Cogut, Laura Errecalde, Fernando Pasteran, Alejandra Corso, and Sonia A. Gomez
Subjects: NDM-1, Providencia rettgeri, plasmid, TnAs2, ISKox2, Microbiology, QR1-502
Abstract: ABSTRACT The first cases of bla NDM in Argentina were detected in three Providencia rettgeri (Pre) recovered from two hospitals in Buenos Aires city in 2013. The isolates were genetically related, but the plasmid profile was different. Here, we characterized the bla NDM-1-harboring plasmids of the first three cases detected in Argentina. Hybrid assembly obtained from short- and long-read sequencing rendered bla NDM-1 in Col3M plasmids of ca. 320 kb (p15268A_320) in isolate PreM15268, 210 kb (p15758B_210) in PreM15758, and 225 kb (p15973A_225) in PreM15973. In addition, PreM15758 harbored a 98-kb circular plasmid (p15758C_98) flanked by a putative recombination site (hin-TnAs2), with 100% nucleotide ID and coverage with p15628A_320. Analysis of PFGE/S1-nuclease gel, Southern hybridization with bla NDM-1 probe, hybrid assembly of short and long reads suggests that pM15758C_98 can integrate by homologous recombination. The three bla NDM-1-plasmids were non-conjugative in vitro. Moreover, tra genes were incomplete, and oriT was not found in the three bla NDM-1-plasmids. In two isolates, blaNDM-1 was embedded in a partially conserved structure flanked by two ISKox2. In addition, all plasmids harbored aph(3')-Ia, aph(3')-VI, and qnrD1 genes and aac(6´)Ib-cr, bla OXA-1, catB3, and arr3 as part of a class 1 integron. Also, p15268A_320 and p15973A_225 harbored bla PER-2. To the best of our knowledge, this is the first report of clinical P. rettgeri harboring blaNDM-1 in an atypical genetic environment and located in unusual chimeric Col3M plasmids. The study and continuous surveillance of these pathogens are crucial to tracking the evolution of these resistant plasmids and finding solutions to tackle their dissemination. IMPORTANCE Infections caused by carbapenem hydrolyzing enzymes like NDM (New Delhi metallo-beta-lactamase) represent a serious problem worldwide because they restrict available treatment options and increase morbidity and mortality, and treatment failure prolongs hospital stays. The first three cases of NDM in Argentina were caused by genetically related P. rettgeri recovered in two hospitals. In this work, we studied the genetic structure of the plasmids encoding bla NDM in those index cases and revealed the enormous plasticity of these genetic elements. In particular, we found a small plasmid that was also found inserted in the larger plasmids by homologous recombination as a co-integrate element. We also found that the bla NDM plasmids were not able to transfer or move to other hosts, suggesting their role as reservoir elements for the acquisition of resistance genes. It is necessary to unravel the dissemination strategies and the evolution of these resistant plasmids to find solutions to tackle their spread.
Published: 2023
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4. Acinetobacter baumannii response to cefiderocol challenge in human urine

Author: Brent Nishimura, Jenny Escalante, Marisel R. Tuttobene, Tomás Subils, Vyanka Mezcord, Camila Pimentel, Nardin Georgeos, Fernando Pasteran, Cecilia Rodriguez, Rodrigo Sieira, Luis A. Actis, Marcelo E. Tolmasky, Robert A. Bonomo, and María Soledad Ramirez
Subjects: Medicine, Science
Abstract: Abstract Cefiderocol (CFDC) is a novel chlorocatechol-substituted siderophore antibiotic approved to treat complicated urinary tract infections (cUTI) and hospital-acquired and ventilator-acquired pneumonia (HAP/VAP). Previous work determined that albumin-rich human fluids increase the minimum inhibitory concentration (MICs) of Acinetobacter baumannii against CFDC and reduce the expression of genes related to iron uptake systems. This latter effect may contribute to the need for higher concentrations of CFDC to inhibit growth. The presence of human urine (HU), which contains low albumin concentrations, did not modify MIC values of two carbapenem-resistant A. baumannii. Levels of resistance to CFDC were not modified by HU in strain AMA40 but were reduced in strain AB5075. Expanding the studies to other carbapenem-resistant A. baumannii isolates showed that the presence of HU resulted in unmodified or reduced MIC of CDFC values. The expression of piuA , pirA , bauA, and bfnH determined by qRT-PCR was enhanced in A. baumannii AMA40 and AB5075 by the presence of HU in the culture medium. All four tested genes code for functions related to recognition and transport of ferric-siderophore complexes. The effect of HU on expression of pbp1, pbp3, bla OXA-51-like, bla ADC, and bla NDM-1, genes associated with resistance to β-lactams, as well as genes coding for efflux pumps and porins was variable, showing dependence with the strain analyzed. We conclude that the lack of significant concentrations of albumin and free iron in HU makes this fluid behave differently from others we tested. Unlike other albumin rich fluids, the presence of HU does not impact the antibacterial activity of CFDC when tested against A. baumannii.
Published: 2022
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5. Novel Metallo-β-Lactamase blaCVI-1 Isolated from a Chromobaterium violaceum Clinical Strain Resistant to Colistin

Author: Sonia A. Gomez, María Belén Sanz, Melina Rapoport, Graciela Sucin, Teresa A. Corallo, Tomás Poklepovich, Josefina Campos, Paola Ceriana, Juan Manuel de Mendieta, Mónica Prieto, Fernando Pasteran, and Alejandra Corso
Subjects: Chomobacterium violaceum, carbapenemase, metallo-beta-lactamase, colistin resistance, CVI-1, Medicine
Abstract: Objective: We aimed to describe a colistin (COL)-resistant (R) Chromobacterium violaceum (Cvi) isolate from a septic patient in Argentina expressing a previously unknown gene, blaCVI-1. Methods: In 2019, a 12 year old child was injured with a thorn in a lagoon. The child was hospitalized due to sepsis and multiple abscesses. Cvi was isolated from skin and soft tissue and tracheal aspirate. The patient was successfully treated with imipenem (IMI) plus amikacin. Antimicrobial susceptibility was assessed by disk diffusion, broth microdilution, and the E-test. Carbapenemase activity was assayed by double-disk synergy and microbiological tests. Resistance, virulence, and additional gene searches were performed by in silico analysis of sequences obtained by whole-genome sequencing (WGS). A maximum likelihood phylogenetic tree was built with public Cvi genomes. Results: R was seen for IMI and COL. Expression of a metallo-β-lactamase was confirmed. Genome analysis revealed blaCVI-1, a subclass B2 metallo-β-lactamase with 62.66% ID with CphA from A. hydrophila (WP081086394). R to COL could be attributed to the arnC and arnT genes. Virulence factors required for invasion and toxicity were also found. No plasmids were detected. The phylogeny tree showed two main clades with geographical distinction, and the isolate studied here stands alone in a branch closely related to two clinical isolates from the USA. Conclusions: This is the second report of infection by Cvi in Argentina. This pathogen carried a new gene, blaCVI-1, a metallo-β-lactamase that can be detected by routine methods. Prompt suspicion of C. violaceum infection is crucial to treating this rare pathogen rapidly and properly.
Published: 2023
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6. Induced Heteroresistance in Carbapenem-Resistant Acinetobacter baumannii (CRAB) via Exposure to Human Pleural Fluid (HPF) and Its Impact on Cefiderocol Susceptibility

Author: Vyanka Mezcord, Jenny Escalante, Brent Nishimura, German M. Traglia, Rajnikant Sharma, Quentin Vallé, Marisel R. Tuttobene, Tomás Subils, Ingrid Marin, Fernando Pasteran, Luis A. Actis, Marcelo E. Tolmasky, Robert A. Bonomo, Gauri Rao, and María S. Ramirez
Subjects: Acinetobacter baumannii, human pleural fluid, cefiderocol, NDM-1, carbapenem-resistance, whole-genome sequencing, Biology (General), QH301-705.5, Chemistry, QD1-999
Abstract: Infections caused by Carbapenem-resistant Acinetobacter baumannii (CRAB) isolates, such as hospital-acquired pneumonia (HAP), bacteremia, and skin and soft tissue infections, among others, are particularly challenging to treat. Cefiderocol, a chlorocatechol-substituted siderophore antibiotic, was approved by the U.S. Food and Drug Administration (FDA) in 2019 and prescribed for the treatment of CRAB infections. Despite the initial positive treatment outcomes with this antimicrobial, recent studies reported a higher-than-average all-cause mortality rate in patients treated with cefiderocol compared to the best available therapy. The cause(s) behind these outcomes remains unconfirmed. A plausible hypothesis is heteroresistance, a phenotype characterized by the survival of a small proportion of cells in a population that is seemingly isogenic. Recent results have demonstrated that the addition of human fluids to CRAB cultures leads to cefiderocol heteroresistance. Here, we describe the molecular and phenotypic analyses of CRAB heteroresistant bacterial subpopulations to better understand the nature of the less-than-expected successful outcomes after cefiderocol treatment. Isolation of heteroresistant variants of the CRAB strain AMA40 was carried out in cultures supplemented with cefiderocol and human pleural fluid (HPF). Two AMA40 variants, AMA40 IHC1 and IHC2, were resistant to cefiderocol. To identify mutations and gene expression changes associated with cefiderocol heteroresistance, we subjected these variants to whole genome sequencing and global transcriptional analysis. We then assessed the impact of these mutations on the pharmacodynamic activity of cefiderocol via susceptibility testing, EDTA and boronic acid inhibition analysis, biofilm formation, and static time-kill assays. Heteroresistant variants AMA40 IHC1 and AMA40 IHC2 have 53 chromosomal mutations, of which 40 are common to both strains. None of the mutations occurred in genes associated with high affinity iron-uptake systems or β-lactam resistance. However, transcriptional analyses demonstrated significant modifications in levels of expression of genes associated with iron-uptake systems or β-lactam resistance. The blaNDM-1 and blaADC-2, as well as various iron-uptake system genes, were expressed at higher levels than the parental strain. On the other hand, the carO and ompA genes’ expression was reduced. One of the mutations common to both heteroresistant strains was mapped within ppiA, a gene associated with iron homeostasis in other species. Static time-kill assays demonstrated that supplementing cation-adjusted Mueller–Hinton broth with human serum albumin (HAS), the main protein component of HPF, considerably reduced cefiderocol killing activity for all three strains tested. Notably, collateral resistance to amikacin was observed in both variants. We conclude that exposing CRAB to fluids with high HSA concentrations facilitates the rise of heteroresistance associated with point mutations and transcriptional upregulation of genes coding for β-lactamases and biofilm formation. The findings from this study hold significant implications for understanding the emergence of CRAB resistance mechanisms against cefiderocol treatment. This understanding is vital for the development of treatment guidelines that can effectively address the challenges posed by CRAB infections.
Published: 2023
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7. Zidebactam restores sulbactam susceptibility against carbapenem-resistant Acinetobacter baumannii isolates

Author: Jose Cedano, Michelle Baez, Fernando Pasteran, Sabrina Daiana Montaña, Grace Ra, Venjaminne Fua, Alejandra Corso, Marcelo E. Tolmasky, Robert A. Bonomo, and María Soledad Ramírez
Subjects: Acinetobacter, carbapenem-resistance, zidebactam, sulbactam, DBOs, synergy, Microbiology, QR1-502
Abstract: Carbapenems are commonly used to treat infections caused by multidrug-resistant (MDR) bacteria. Unfortunately, carbapenem resistance is increasingly reported in many gram-negative bacteria, especially Acinetobacter baumannii. Diazabicyclooctane (DBO) β-lactamase inhibitors, such as avibactam (AVI), when combined with sulbactam successfully restore sulbactam susceptibility against certain carbapenem-resistant A. baumannii (CRAB) isolates. In the present study, we tested zidebactam, a novel DBO with an additional mechanism of action, in combination with sulbactam against CRAB isolates, including strains that exhibited resistance against sulbactam/avibactam combination. A panel of 43 geographically and genetically distinct CRAB isolates recovered from different hospitals and containing different mechanisms of resistance were included in the present study. We also tested three reference strains (AB0057, AB5075, and AYE). Minimum inhibitory concentrations (MICs) for sulbactam (range 0.12–512 mg/l) and sulbactam plus 4 mg/l zidebactam were performed using microdilution according to CLSI Standards. A decrease ≥2 dilutions in sulbactam MICs was observed in 84% of the isolates when tested in combination with zidebactam. The sulbactam/zidebactam combination was able to restore sulbactam susceptibility in 91% of the isolates, including isolates that were resistant to sulbactam/avibactam combination. These data encouraged us to further explore sulbactam/zidebactam in other experimental models especially against CRAB isolates resistant to other DBOs.
Published: 2022
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8. Carbapenemase-Producing Extraintestinal Pathogenic Escherichia coli From Argentina: Clonal Diversity and Predominance of Hyperepidemic Clones CC10 and CC131

Author: María Belén Sanz, Denise De Belder, JM de Mendieta, Diego Faccone, Tomás Poklepovich, Celeste Lucero, Melina Rapoport, Josefina Campos, Ezequiel Tuduri, Mathew O. Saavedra, Claudia Van der Ploeg, Ariel Rogé, Carbapenemases-ExPEC Group, Fernando Pasteran, Alejandra Corso, Adriana E. Rosato, Sonia A. Gomez, A. Piersigulli, H. Aleman, O. Veliz, N. Giudice, A. Sujemecki, N. Cerda, Leticia Bardi, A. Rodriguez, H. Gral, M. Badi, H. Gral de Agudos, M. Flabiani, A. Togneri, P. Andrés, E. Biondi, M. Rocallo, M. Gerardo, S. Ortiz, H. Heller, H. Sauer, M. Carol Rey, H. Naval, J. C. Pidone, M. E. Bongiovanni, M. Vilaro, H. Santojanni, C. Alfonodo, M. Z. Bartoli, L. Vacaflor, L. Gonzalez, M. A. Visus, L. Errecalde, B. Baudaz, C. Tula, A. de Paulis, A. Littvik, M. R. Nuñez, A. L. Mariñansky, A. M. Romeo, A. Di Bella, D. Archuby, L. Bottinelli, S. Zarate, M. Reynaldi, and S. Manganello
Subjects: ExPEC, carbapenemase, Escherichia coli, phylogeny, high risk clone, Microbiology, QR1-502
Abstract: Extraintestinal pathogenic Escherichia coli (ExPEC) causes infections outside the intestine. Particular ExPEC clones, such as clonal complex (CC)/sequence type (ST)131, have been known to sequentially accumulate antimicrobial resistance that starts with chromosomal mutations against fluoroquinolones, followed with the acquisition of blaCTX–M–15 and, more recently, carbapenemases. Here we aimed to investigate the distribution of global epidemic clones of carbapenemase-producing ExPEC from Argentina in representative clinical isolates recovered between July 2008 and March 2017. Carbapenemase-producing ExPEC (n = 160) were referred to the Argentinean reference laboratory. Of these, 71 were selected for genome sequencing. Phenotypic and microbiological studies confirmed the presence of carbapenemases confirmed as KPC-2 (n = 52), NDM-1 (n = 16), IMP-8 (n = 2), and VIM-1 (n = 1) producers. The isolates had been recovered mainly from urine, blood, and abdominal fluids among others, and some were from screening samples. After analyzing the virulence gene content, 76% of the isolates were considered ExPEC, although non-ExPEC isolates were also obtained from extraintestinal sites. Pan-genome phylogeny and clonal analysis showed great clonal diversity, although the first phylogroup in abundance was phylogroup A, harboring CC10 isolates, followed by phylogroup B2 with CC/ST131, mostly H30Rx, the subclone co-producing CTX-M-15. Phylogroups D, B1, C, F, and E were also detected with fewer strains. CC10 and CC/ST131 were found throughout the country. In addition, CC10 nucleated most metalloenzymes, such as NDM-1. Other relevant international clones were identified, such as CC/ST38, CC155, CC14/ST1193, and CC23. Two isolates co-produced KPC-2 and OXA-163 or OXA-439, a point mutation variant of OXA-163, and three isolates co-produced MCR-1 among other resistance genes. To conclude, in this work, we described the molecular epidemiology of carbapenemase-producing ExPEC in Argentina. Further studies are necessary to determine the plasmid families disseminating carbapenemases in ExPEC in this region.
Published: 2022
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9. Plasmidic resistance to colistin mediated by mcr-1 gene in Escherichia coli clinical isolates in Argentina: A retrospective study, 2012–2018

Author: Diego Faccone, Melina Rapoport, Ezequiel Albornoz, Federico Celaya, Juan De Mendieta, Denise De Belder, Celeste Lucero, Sonia Gomez, Diego Danze, Fernando Pasteran, Alejandra Corso, and Mobilizable Colistin Resistance Group
Subjects: drug resistance, multiple, colistin, enterobacteriaceae, escherichia coli, argentina, Medicine, Arctic medicine. Tropical medicine, RC955-962, Public aspects of medicine, RA1-1270
Abstract: Objective. To describe the resistance profile and the genetic characteristics of Escherichia coli isolates that harbor the mobilizable colistin resistance gene mcr-1 in Argentina. Methods. This was a retrospective study of 192 E. coli isolates positive for mcr-1 obtained from 69 hospitals of Buenos Aires City and 14 Argentinean provinces in 2012 – 2018. The antimicrobial susceptibility was performed by agar diffusion, broth macrodilution, and/or agar dilution. Standard polymerase chain reaction (PCR) was performed to detect resistance genes and incompatibility groups; specific PCR was applied to discriminate between blaCTX-M allelic groups and mcr-1.5 variant. The genetic relatedness among isolates was evaluated by XbaI-pulsed field gel electrophoresis and multilocus sequence typing in a subset of isolates. Results. All E. coli isolates showed minimal inhibitory concentrations to colistin ≥ 4μg/mL; nearly 50% were resistant to third-generation cephalosporins, with CTX-M-2 being the main extended-spectrum β-lactamase detected. Five E. coli were carbapenemase-producers (3 NDM, 2 KPC). The mcr-1.5 variant was detected in 13.5% of the isolates. No genetic relationship was observed among the mcr-1-positive E. coli clinical isolates, but a high proportion (164/192; 85.4%) of IncI2 plasmids was detected. Conclusions. The presence of IncI2 plasmids among highly diverse E. coli clones suggests that the mcr-1 gene’s wide distribution in Argentina may be driven by the horizontal transmission of IncI2 plasmids.
Published: 2020
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10. Evolución del desempeño de Laboratorios de Referencia de América Latina en la detección de mecanismos de resistencia a los antimicrobianos

Author: Paula Gagetti, Fernando Pasteran, Paola Ceriana, Mónica Prieto, Lucía Cipolla, Ezequiel Tuduri, Nienke Bruinsma, Marcelo Galas, Pilar Ramón-Pardo, en representación del Programa Latinoamericano de Control de Calidad en Bacteriología y Resistencia a los Antimicrobianos (LA-EQAS), and A Corso
Subjects: antimicrobianos, vigilancia, control de calidad, bacteriología, américa latina, Medicine, Arctic medicine. Tropical medicine, RC955-962, Public aspects of medicine, RA1-1270
Abstract: Objetivo. El objetivo es presentar los resultados del Programa Latinoamericano de Aseguramiento de la Calidad en Bacteriología y Resistencia a los Antimicrobianos (LA-EQAS) entre 2000 y 2018 y la evolución en la detección de mecanismos de resistencia de impacto clínico. Métodos. Los Laboratorios Nacionales de Referencia (LNR) participantes recibieron 25 encuestas con 10 cepas cada una, representando un total de 86 especies bacterianas y 40 mecanismos de resistencia. Para evaluar el desempeño de los LNR, se analizaron cinco indicadores: identificación bacteriana, interpretación de las pruebas de sensibilidad, rangos de las zonas de inhibición aceptables, mecanismo de resistencia inferido, y tiempo de demora en la respuesta. Resultados. La concordancia media fue 82,6% (rango: 74-95%) en la identificación bacteriana, 93,3% (85-98%) en la interpretación de las pruebas de sensibilidad, 84,6% (70-94%) en las zonas de inhibición, 82,5% (73-96%) en el mecanismo de resistencia inferido, y la demora en la respuesta, 34 días. Se observó una mejora en la detección de mecanismos de relevancia clínica como resistencia a meticilina, macrólidos y glucopéptidos en cocos gram positivos, y betalactamasas de espectro extendido, AmpC plasmídico y carbapenemasas en bacilos gram negativos. Conclusiones. El LA-EQAS es una excelente herramienta para la mejora continua de la calidad en el diagnóstico de las infecciones por microorganismos multirresistentes en los LNR de América Latina.
Published: 2020
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11. Genomic Comparative Analysis of Two Multi-Drug Resistance (MDR) Acinetobacter baumannii Clinical Strains Assigned to International Clonal Lineage II Recovered Pre- and Post-COVID-19 Pandemic

Author: German Matias Traglia, Fernando Pasteran, Jenny Escalante, Brent Nishimura, Marisel R. Tuttobene, Tomás Subils, Maria Rosa Nuñez, María Gabriela Rivollier, Alejandra Corso, Marcelo E. Tolmasky, and Maria Soledad Ramirez
Subjects: Acinetobacter baumannii MDR, ST-2, COVID-19, blaOXA-23, blaNDM-1, Biology (General), QH301-705.5
Abstract: Background: After the emergence of COVID-19, numerous cases of A. baumannii/SARS-CoV-2 co-infection were reported. Whether the co-infecting A. baumannii strains have distinctive characteristics remains unknown. Methods and Results: A. baumannii AMA_NO was isolated in 2021 from a patient with COVID-19. AMA166 was isolated from a mini-BAL used on a patient with pneumonia in 2016. Both genomes were similar, but they possessed 337 (AMA_NO) and 93 (AMA166) unique genes that were associated with biofilm formation, flagellar assembly, antibiotic resistance, secretion systems, and other functions. The antibiotic resistance genes were found within mobile genetic elements. While both strains harbored the carbapenemase-coding gene blaOXA-23, only the strain AMA_NO carried blaNDM-1. Representative functions coded for by virulence genes are the synthesis of the outer core of lipooligosaccharide (OCL5), biosynthesis and export of the capsular polysaccharide (KL2 cluster), high-efficiency iron uptake systems (acinetobactin and baumannoferrin), adherence, and quorum sensing. A comparative phylogenetic analysis including 239 additional sequence type (ST) 2 representative genomes showed high similarity to A. baumannii ABBL141. Since the degree of similarity that was observed between A. baumannii AMA_NO and AMA166 is higher than that found among other ST2 strains, we propose that they derive from a unique background based on core-genome phylogeny and comparative genome analysis. Conclusions: Acquisition or shedding of specific genes could increase the ability of A. baumannii to infect patients with COVID-19.
Published: 2023
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12. Characterisation of ST25 NDM-1-producing Acinetobacter spp. strains leading the increase in NDM-1 emergence in Argentina

Author: Deja Rodgers, Fernando Pasteran, Manuel Calderon, Sara Jaber, German M. Traglia, Ezequiel Albornoz, Alejandra Corso, Alejandro J. Vila, Robert A. Bonomo, Mark D. Adams, and María Soledad Ramírez
Subjects: Microbiology, QR1-502
Published: 2020
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13. Human Serum Proteins and Susceptibility of Acinetobacter baumannii to Cefiderocol: Role of Iron Transport

Author: Casin Le, Camila Pimentel, Fernando Pasteran, Marisel R. Tuttobene, Tomás Subils, Jenny Escalante, Brent Nishimura, Susana Arriaga, Aimee Carranza, Vyanka Mezcord, Alejandro J. Vila, Alejandra Corso, Luis A. Actis, Marcelo E. Tolmasky, Robert A. Bonomo, and Maria Soledad Ramírez
Subjects: Acinetobacter baumannii, cefiderocol, human fluids, iron, human serum albumin, Biology (General), QH301-705.5
Abstract: Cefiderocol, a recently introduced antibiotic, has a chemical structure that includes a cephalosporin that targets cell wall synthesis and a chlorocatechol siderophore moiety that facilitates cell penetration by active iron transporters. Analysis of the effect that human serum, human serum albumin, and human pleural fluid had on growing Acinetobacter baumannii showed that genes related to iron uptake were down-regulated. At the same time, β-lactamase genes were expressed at higher levels. The minimum inhibitory concentrations of this antimicrobial in A. baumannii cells growing in the presence of human serum, human serum albumin, or human pleural fluid were higher than those measured when these fluids were absent from the culture medium. These results correlate with increased expression levels of β-lactamase genes and the down-regulation of iron uptake-related genes in cultures containing human serum, human serum albumin, or human pleural fluid. These modifications in gene expression could explain the less-than-ideal clinical response observed in patients with pulmonary or bloodstream A. baumannii infections. The exposure of the infecting cells to the host’s fluids could cause reduced cefiderocol transport capabilities and increased resistance to β-lactams. The regulation of genes that could impact the A. baumannii susceptibility to cefiderocol, or other antibacterials, is an understudied phenomenon that merits further investigation.
Published: 2022
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14. Resistencia a colistín mediado por el gen mcr-1 identificado en cepas de Escherichia coli y Klebsiella pneumoniae. Primeros reportes en el Perú

Author: Ruth Giovanna Ugarte Silva, José Maria Olivo López, Alejandra Corso, Fernando Pasteran, Ezequiel Albornoz, and Zaida Patricia Sahuanay Blácido
Subjects: colistín, farmacorresistencia microbiana, escherichia coli, klebsiella pneumoniae, Medicine, Medicine (General), R5-920
Abstract: Introducción. Ante la aparición de reportes de la presencia del gen mcr-1 y su posible diseminación por plásmidos en los países de la región y dado que este gen confiere resistencia a colistín, fármaco que es la última línea de tratamiento contra bacterias multirresistentes, es importante conocer su presencia en nuestro país en microorganismos que lo expresen. Métodos. Se realizó un estudio descriptivo y transversal. Se incluyeron microorganismos aislados de urocultivos de pacientes ambulatorios de un centro de salud privado en Lima, Perú, en agosto del año 2017. De 326 urocultivos positivos se seleccionaron 10 aislamientos entre cepas de Escherichia coli y Klebsiella pneumoniae que presentaron concentración mínima inhibitoria ≥4μg/mL (interpretado como resistente para colistín) por el sistema automatizado Microscan Walkaway 96 plus. Se utilizaron los siguientes métodos: colistín agar spot, predifusión con tabletas de colistín, microdilución en caldo colistin y PCR para el gen mcr-1. Resultados. Se determinó que 7 aislamientos, todas Escherichia coli, expresaron la presencia del gen mcr-1 por PCR, el cual confiere resistencia plasmídica a polipéptidos. De las cepas restantes, dos Escherichia coli y una Klebsiella pneumoniae, resultaron positivos para resistencia a colistín en las pruebas fenotípicas pero no en la PCR para gen mcr-1 lo cual sugiere un mecanismo de resistencia a colistín no asociado a gen mcr-1. Conclusiones. Se obtuvieron 7 aislamientos de Escherichia coli resistentes a colistín y con expresión del gen mcr-1.
Published: 2018
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15. A New Twist: The Combination of Sulbactam/Avibactam Enhances Sulbactam Activity against Carbapenem-Resistant Acinetobacter baumannii (CRAB) Isolates

Author: Fernando Pasteran, Jose Cedano, Michelle Baez, Ezequiel Albornoz, Melina Rapoport, Jose Osteria, Sabrina Montaña, Casin Le, Grace Ra, Robert A. Bonomo, Marcelo E. Tolmasky, Mark Adams, Alejandra Corso, and Maria Soledad Ramirez
Subjects: Acinetobacter, carbapenem-resistance, sulbactam, avibactam, relebactam, Therapeutics. Pharmacology, RM1-950
Abstract: An increasing number of untreatable infections are recorded every year. Many studies have focused their efforts on developing new β-lactamase inhibitors to treat multi-drug resistant (MDR) isolates. In the present study, sulbactam/avibactam and sulbactam/relebactam combination were tested against 187 multi-drug resistant (MDR) Acinetobacter clinical isolates; both sulbactam/avibactam and sulbactam/relebactam restored sulbactam activity. A decrease ≥2 dilutions in sulbactam MICs was observed in 89% of the isolates when tested in combination with avibactam. Sulbactam/relebactam was able to restore sulbactam susceptibility in 40% of the isolates. In addition, the susceptibility testing using twenty-three A. baumannii AB5075 knockout strains revealed potential sulbactam and/or sulbactam/avibactam target genes. We observed that diazabicyclooctanes (DBOs) β-lactamase inhibitors combined with sulbactam restore sulbactam susceptibility against carbapenem-resistant Acinetobacter clinical isolates. However, relebactam was not as effective as avibactam when combined with sulbactam. Exploring novel combinations may offer new options to treat Acinetobacter spp. infections, especially for widespread oxacillinases and metallo-β-lactamases (MBLs) producers.
Published: 2021
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16. Emergence of KPC-31, a KPC-3 Variant Associated with Ceftazidime-Avibactam Resistance, in an Extensively Drug-Resistant ST235 Pseudomonas aeruginosa Clinical Isolate

Author: Diego Faccone, Juan M. de Mendieta, Ezequiel Albornoz, Magali Chavez, Fabiana Genero, Mariano Echegorry, Paola Ceriana, Andrea Mora, Christine Seah, Alejandra Corso, Roberto G. Melano, and Fernando Pasteran
Subjects: Pharmacology, Microbial Sensitivity Tests, Ceftazidime, beta-Lactamases, Anti-Bacterial Agents, Klebsiella pneumoniae, Drug Combinations, Infectious Diseases, Bacterial Proteins, Mechanisms of Resistance, Pseudomonas aeruginosa, Humans, Pharmacology (medical), Azabicyclo Compounds
Abstract: A ceftazidime-avibactam-resistant KPC-producing Pseudomonas aeruginosa strain was isolated in Argentina from a tracheal aspirate. The patient was treated with ceftazidime-avibactam in combination with other agents for 130 days. Whole-genome sequencing of P. aeruginosa identified a D179Y substitution in the Ω loop of KPC-3, corresponding to KPC-31, integrated at the chromosome. The strain belonged to the sequence type 235/O11 (ST235/O11) high-risk clone. Evaluation of carbapenemase detection assays most used by clinical laboratories failed to identify the isolate as a KPC producer.
Published: 2023

17. Role of β-lactamase inhibitors on cefiderocol activity against carbapenem-resistant Acinetobacter species

Author: Vyanka Mezcord, Olivia Wong, Fernando Pasteran, Alejandra Corso, Marcelo E. Tolmasky, Robert A. Bonomo, and María Soledad Ramirez
Subjects: Microbiology (medical), Infectious Diseases, Pharmacology (medical), General Medicine, Article
Published: 2022

18. Carbapenemase-Producing Extraintestinal Pathogenic

Author: María Belén, Sanz, Denise, De Belder, J M, de Mendieta, Diego, Faccone, Tomás, Poklepovich, Celeste, Lucero, Melina, Rapoport, Josefina, Campos, Ezequiel, Tuduri, Mathew O, Saavedra, Claudia, Van der Ploeg, Ariel, Rogé, Fernando, Pasteran, Alejandra, Corso, Adriana E, Rosato, and S, Manganello
Abstract: Extraintestinal pathogenic
Published: 2021

19. Characterisation of ST25 NDM-1-producing Acinetobacter spp. strains leading the increase in NDM-1 emergence in Argentina

Author: Maria Soledad Ramirez, Fernando Pasteran, Alejandra Corso, Ezequiel Albornoz, Manuel Calderon, Alejandro J. Vila, Mark Raymond Adams, German Matias Traglia, Robert A. Bonomo, Deja Rodgers, and Sara Jaber
Subjects: Acinetobacter baumannii, 0301 basic medicine, Microbiology (medical), Carbapenems Resistance, 030106 microbiology, Immunology, Argentina, NDM-1, Microbiology, beta-Lactamases, Article, 03 medical and health sciences, 0302 clinical medicine, polycyclic compounds, Humans, Immunology and Allergy, 030212 general & internal medicine, Carbapenem resistance, Acinetobacter, biology, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, biology.organism_classification, Disease control, QR1-502, bacteria, Acinetobacter Infections
Abstract: Carbapenem-resistant Acinetobacter baumannii are recognised by the US Centers for Disease Control and Prevention (CDC) as an urgent threat [1]. The most prevalent mechanism of carbapenem resistance in Acinetobacter spp. is due to the presence of carbapenem-hydrolysing class D β-lactamases, with OXA-23 being the most common. The observed dispersion of blaOXA-23 is attributed in part to the spread of successful A. baumannii global clones such as GC1 and GC2 [2]. However, in the most recent years an increased emergence of blaNDM-1-harbouring Acinetobacter spp. isolates has been reported Fil: Rodgers, Deja. California State University. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States. Fil: Pasteran, Fernando. Ministerio de Salud. Administración Nacional de Laboratorios e Institutos de Salud (ANLIS) “Dr. Carlos G. Malbrán”. Servicio Antimicrobianos; Argentina. Fil: Calderon, Manuel. California State University. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States. Fil: Jaber, Sara. California State University. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States. Fil: Traglia, German M. Universidad de La República. Facultad de Medicina. Instituto de Higiene. Departamento de Desarrollo Biotecnología; Uruguay. Fil: Albornoz, Ezequiel. Ministerio de Salud. Administración Nacional de Laboratorios e Institutos de Salud (ANLIS) “Dr. Carlos G. Malbrán”. Servicio Antimicrobianos; Argentina. Fil: Corso, Alejandra. Ministerio de Salud. Administración Nacional de Laboratorios e Institutos de Salud (ANLIS) “Dr. Carlos G. Malbrán”. Servicio Antimicrobianos; Argentina. Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina. Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Biofísica; Argentina. Fil: Bonomo, Robert A. Louis Stokes Cleveland Department of Veterans Affairs Medical Center. Research Service and GRECC; United States. Fil: Adams, Mark D. The Jackson Laboratory; United States. Fil: Ramírez, María Soledad. California State University. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.
Published: 2020

20. Impact of Human Serum Proteins on Susceptibility of Acinetobacter baumannii to Cefiderocol: role of iron transport

Author: Fernando Pasteran, Tomas Subils, Marcelo E. Tolmasky, Luis A. Actis, Susana Arriaga, Casin Le, Marisel R. Tuttobene, Alejandra Corso, Brent Nishimura, Robert A. Bonomo, Jenny Escalante, Camila Pimentel, Aimee Carranza, Maria Soledad Ramirez, and Alejandro J. Vila
Subjects: Siderophore, biology, medicine.drug_class, Chemistry, Antibiotics, Transporter, Iron transport, biology.organism_classification, Human serum albumin, Blood proteins, Microbiology, Acinetobacter baumannii, medicine, Gene, medicine.drug
Abstract: Cefiderocol is a siderophore antibiotic that co-opts iron transporters to facilitate cell entry. We show that genes related to iron uptake systems and resistance to β-lactams in Acinetobacter baumannii have altered expression levels in the presence of human serum, human serum albumin, or human pleural fluid. Cefiderocol MICs are also raised in the presence of the mentioned fluids. Clinical response in A. baumannii infections may be related to the interplay of these human factors.
Published: 2021

21. Pseudomonas putida group species as reservoirs of mobilizable Tn402-like class 1 integrons carrying bla

Author: Marco A, Brovedan, Patricia M, Marchiaro, María S, Díaz, Diego, Faccone, Alejandra, Corso, Fernando, Pasteran, Alejandro M, Viale, and Adriana S, Limansky
Subjects: Bacterial Proteins, Carbapenems, Pseudomonas putida, Drug Resistance, Bacterial, DNA Transposable Elements, beta-Lactamases, Anti-Bacterial Agents, Integrons
Abstract: The Pseudomonas putida group (P. putida G) is composed of at least 21 species associated with a wide range of environments, including the clinical setting. Here, we characterized 13 carbapenem-resistant P. putida G clinical isolates bearing class 1 integrons/transposons (class 1 In/Tn) carrying bla
Published: 2021

22. A New Twist: The Combination of Sulbactam/Avibactam Enhances Sulbactam Activity against Carbapenem-Resistant Acinetobacter baumannii (CRAB) Isolates

Author: Michelle Baez, Fernando Pasteran, Sabrina Montaña, Maria Soledad Ramirez, Jose Osteria, Ezequiel Albornoz, Casin Le, Robert A. Bonomo, Mark Raymond Adams, Marcelo E. Tolmasky, Melina Rapoport, jose Cedano, Alejandra Corso, and Grace Ra
Subjects: 0301 basic medicine, Microbiology (medical), Susceptibility testing, sulbactam, Avibactam, 030106 microbiology, Acinetobacter, RM1-950, Biology, Biochemistry, Microbiology, Article, 03 medical and health sciences, chemistry.chemical_compound, relebactam, medicine, Relebactam, polycyclic compounds, Pharmacology (medical), General Pharmacology, Toxicology and Pharmaceutics, avibactam, Carbapenem resistance, organic chemicals, Sulbactam, biochemical phenomena, metabolism, and nutrition, biology.organism_classification, bacterial infections and mycoses, carbapenem-resistance, 030104 developmental biology, Infectious Diseases, chemistry, bacteria, Therapeutics. Pharmacology, Carbapenem resistant Acinetobacter baumannii, medicine.drug
Abstract: An increasing number of untreatable infections are recorded every year. Many studies have focused their efforts on developing new β-lactamase inhibitors to treat multi-drug resistant (MDR) isolates. In the present study, sulbactam/avibactam and sulbactam/relebactam combination were tested against 187 multi-drug resistant (MDR) Acinetobacter clinical isolates, both sulbactam/avibactam and sulbactam/relebactam restored sulbactam activity. A decrease ≥2 dilutions in sulbactam MICs was observed in 89% of the isolates when tested in combination with avibactam. Sulbactam/relebactam was able to restore sulbactam susceptibility in 40% of the isolates. In addition, the susceptibility testing using twenty-three A. baumannii AB5075 knockout strains revealed potential sulbactam and/or sulbactam/avibactam target genes. We observed that diazabicyclooctanes (DBOs) β-lactamase inhibitors combined with sulbactam restore sulbactam susceptibility against carbapenem-resistant Acinetobacter clinical isolates. However, relebactam was not as effective as avibactam when combined with sulbactam. Exploring novel combinations may offer new options to treat Acinetobacter spp. infections, especially for widespread oxacillinases and metallo-β-lactamases (MBLs) producers.
Published: 2021
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23. Pseudomonas putida group species serve as reservoirs of conjugative plasmids disseminating Tn402-like class 1 integrons carrying blaVIM-2 metallo-β-lactamase genes

Author: Patricia Marchiaro, Adriana S. Limansky, María S. Díaz, Fernando Pasteran, Alejandro M. Viale, Diego Faccone, Marco A. Brovedan, and Alejandra Corso
Subjects: Genetics, Transposable element, Plasmid, Phylogenetic tree, biology, Inverted repeat, medicine, biology.organism_classification, medicine.disease_cause, 16S ribosomal RNA, Gene, Escherichia coli, Pseudomonas putida
Abstract: The Pseudomonas putida group (P. putida G) is composed of at least 21 species associated to a wide range of environments, including the clinical setting. Here, we characterized 13 carbapenem-resistant P. putida G clinical isolates carrying blaVIM-2 from different hospitals of Argentina. Multilocus sequencing (MLSA) and phylogenetic analyses based on the 16S rDNA, gyrB and rpoD sequences comparison allowed us to assign them to 7 well-differentiated species. Sequencing analysis revealed that blaVIM-2 genes were carried in these isolates by three different class 1 integrons (In41, In899 and In528) embedded into Tn402-like transposons. Those harboring In41 and In899 were designated Tn6335 and Tn6336, respectively, with the former found among 10 isolates. Both encompassed complete transposition modules and inverted repeats boundaries characteristic of the Tn5053/Tn402 family, whereas the third, bearing In528, exhibited a defective tni module. Tn6335 and Tn6336 were located in conjugative pLD209-type plasmids in P. asiatica, P. juntendi, P. putida G/II, and P. putida G/V isolates, and could be mobilized to Escherichia coli and P. aeruginosa indicating a relevant mechanism of blaVIM-2 dissemination. In other P. asiatica and P. putida G/II isolates, Tn6335 was found inserted into the Tn21 subgroup transposons-res region, indicating capability for intragenomic mobilization and further dissemination associated to Tn3 family transposons. The Tn402-like defective element was also found inserted into the res region of another Tn3 family transposon in a P. monteilii isolate, but in an atypical orientation. Overall findings shed light on the mechanisms by which resistance genes move through environmental and opportunist Pseudomonas species.
Published: 2020

24. Simple Phenotypic Tests To Improve Accuracy in Screening Chromosomal and Plasmid-Mediated Colistin Resistance in Gram-Negative Bacilli

Author: Ezequiel Albornoz, Celeste Lucero, Carla Cabrera, Alejandra Corso, Ignacio Castillo, Fernando Pasteran, Diego Danze, Melina Rapoport, Alejandra Menocal, and Paola Ceriana
Subjects: Microbiology (medical), Veterinary medicine, Bacilli, food.ingredient, medicine.drug_class, Antibiotics, Microbial Sensitivity Tests, medicine.disease_cause, Microbiology, Agar plate, food, Plasmid, Gram-Negative Bacteria, medicine, polycyclic compounds, Agar, Humans, biology, Pseudomonas aeruginosa, business.industry, Colistin, Broth microdilution, Bacteriology, Acinetobacter, biochemical phenomena, metabolism, and nutrition, biology.organism_classification, equipment and supplies, Anti-Bacterial Agents, McFarland standards, bacteria, business, medicine.drug, Plasmids
Abstract: CLSI and EUCAST recommends that only broth microdilution (BMD) should be used for routine colistin susceptibility testing, however, it could be difficult to perform in resource-poor settings. The purpose of this study was to evaluate the accuracy of an agar spot test (COL-AS) and a colistin drop test (COL-DT) as compared to BMD. COL-AS and COL-DT were challenged with a collection of 271 Gram-negative bacilli clinical isolates: 195 Enterobacterales (including 63 mcr-1 positive strains), 37 Acinetobacter spp. and 39 P. aeruginosa. For COL-AS, 3.0µg/ml (final concentration) of colistin was added to a Mueller-Hinton agar plate and subsequently swabbed with a 0.5 McFarland suspension of tested strain within 1cm2 spot. For COL-DT, 10µl of a 16µg/ml colistin solution was dripped on the surface of a Mueller-Hinton agar plate, previously inoculated with a lawn of tested strain (0.5 McFarland). Colistin solution was made either, by dissolving powder or by disk elution in CA-MHB. Overall, 141/271 (52%) isolates were categorized as colistin resistant by reference BMD. COL-AS yielded a categorical agreement (CA) of 95.5% compared to BMD, with 0.7% very major errors and 3.8% major errors. COL-DR yielded a CA of 96.2% compared to BMD, with 0.7% and 0% very major errors and 3.1% and 3.8% major errors, for colistin powder and disk elution solutions, respectively. Most major errors occurred for mcr-1 producing strains with MICs that fluctuated from 2 to 4 μg/ml. In conclusion, we developed and validated methods suited to the systematic screening of resistance to colistin in gram negative bacilli.Clinical relevancecolistin continues to be one of the last-line therapeutic options to treat carbapenemase-producing gram negative bacilli. The BMD reference methodology, the only one accepted by current standards for evaluating colistin sensitivity, is difficult to implement in laboratories from low-resource countries. In this work, we propose two simple methodologies to screen for colistin resistance, with a performance equivalent to the reference method in detecting resistance to colistin, both of plasmid (mcr) and chromosomal nature. Furthermore, the methods validated here allowed a better identification of those producers of mcr producer with borderline MICs. These screening tests can be routinely performed in addition to the tests currently in use. showed long stability during storage and some of them do not require colistin powder as the source of antibiotic, an important limitation in low-resource countries.
Published: 2020

25. Comparative Kinetic Analysis of OXA-438 with Related OXA-48-Type Carbapenem-Hydrolyzing Class D β-Lactamases

Author: Alejandra Corso, Adriana Di Bella, Lucrecia María Curto, Pablo Power, Barbara Ghiglione, Gabriel Osvaldo Gutkind, Juan Manuel de Mendieta, Denise Gisele de Belder, Sonia Gomez, and Fernando Pasteran
Subjects: 0301 basic medicine, Carbapenem, Cefotaxime, OXA-163, 030106 microbiology, Ceftazidime, Β5−Β6 LOOP, Microbial Sensitivity Tests, Meropenem, beta-Lactamases, CARBAPENEMASES, purl.org/becyt/ford/1 [https], 03 medical and health sciences, chemistry.chemical_compound, polycyclic compounds, medicine, Enzyme kinetics, purl.org/becyt/ford/1.6 [https], chemistry.chemical_classification, integumentary system, Strain (chemistry), biochemical phenomena, metabolism, and nutrition, Molecular biology, Cephalosporins, OXYIMINO-CEPHALOSPORINS, Kinetics, 030104 developmental biology, Infectious Diseases, Enzyme, Carbapenems, chemistry, bacteria, Ertapenem, SODIUM BICARBONATE, medicine.drug
Abstract: Novel variants of OXA-48-type enzymes with the ability to hydrolyze oxyimino-cephalosporins and carbapenems are increasingly reported. Since its first report in 2011, OXA-163 is now extensively spread throughout Argentina, and several variants like OXA-247 have emerged. Here, we characterized a new blaOXA-48-like variant, OXA-438, and we performed a comparative kinetic analysis with the local variants OXA-247 and OXA-163 and the internationally disseminated OXA-48. blaOXA-163, blaOXA-247, and blaOXA-438 were located in a 70 kb IncN2 conjugative plasmid. OXA-438 presented mutations in the vicinity of conserved KTG (214-216), with a 2-aa deletion (R220-I221) and a D224E shift (as in OXA-163) compared to OXA-48. Despite Kpn163 (OXA-163), Kpn247 (OXA-247) and Eco438 (OXA-438) were resistant to meropenem and ertapenem, and the transconjugants (TC) remained susceptible (however, the carbapenems minimum inhibitory concentrations were ≥3 times 2-fold dilutions higher than the acceptor strain). TC163 and Eco48 were resistant to oxyimino-cephalosporins, unlike TC247 and TC438. kcat/Km values for cefotaxime in OXA-163 were slightly higher than the rest of the variants that were accompanied by a lower Km for carbapenems. For OXA-163, OXA-247, and OXA-438, the addition of NaHCO3 improved kcat values for both cefotaxime and ceftazidime; carbapenems kcat/Km values were higher than for oxyimino-cephalosporins. Mutations occurring near the conserved KTG in OXA-247 and OXA-438 are probably responsible for the improved carbapenems hydrolysis and decreased inactivation of oxyimino-cephalosporins compared to OXA-163. Dichroism results suggest that deletions at the β5-β6 loop seem to impact the structural stability of OXA-48 variants. Finally, additional mechanisms are probably involved in the resistance pattern observed in the clinical isolates. Fil: de Belder, Denise Gisele. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina Fil: Ghiglione, Barbara. Instituto de Investigaciones En Bacteriologia y Virologia Molecular (ibavim) ; Facultad de Farmacia y Bioquimica ; Universidad de Buenos Aires; . Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: de Mendieta, Juan Manuel. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Curto, Lucrecia María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Di Bella, Adriana. Hospital Nacional Profesor Alejandro Posadas; Argentina Fil: Gutkind, Gabriel Osvaldo. Instituto de Investigaciones En Bacteriologia y Virologia Molecular (ibavim) ; Facultad de Farmacia y Bioquimica ; Universidad de Buenos Aires; . Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina Fil: Gómez, Sonia Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina Fil: Power, Pablo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología; Argentina. Instituto de Investigaciones En Bacteriologia y Virologia Molecular (ibavim) ; Facultad de Farmacia y Bioquimica ; Universidad de Buenos Aires
Published: 2020

26. Distinct Mechanisms of Dissemination of NDM-1 Metallo-β-Lactamase in Acinetobacter Species in Argentina

Author: Lisandro J González, Jennifer S. Fernandez, Jasmine Martinez, German Matias Traglia, Mark Raymond Adams, Carolina Lopez, Maria Soledad Ramirez, Robert A. Bonomo, Alejandro J. Vila, Fernando Pasteran, Christine Liu, Fanny Huang, Alejandra Corso, and Ezequiel Albornoz
Subjects: Pharmacology, 0303 health sciences, biology, 030306 microbiology, Chromosome, biochemical phenomena, metabolism, and nutrition, Acinetobacter, bacterial infections and mycoses, biology.organism_classification, Genome, DNA sequencing, Metallo β lactamase, Microbiology, Acinetobacter baumannii, 03 medical and health sciences, Infectious Diseases, Plasmid, Pharmacology (medical), Gene, 030304 developmental biology
Abstract: A 4-year surveillance of carbapenem-resistant Acinetobacter spp. isolates in Argentina identified 40 strains carrying bla NDM-1 . Genome sequencing revealed that most were Acinetobacter baumannii , whereas seven represented other Acinetobacter spp. The A. baumannii genomes were closely related, suggesting recent spread. bla NDM-1 was located in the chromosome of A. baumannii strains and on a plasmid in non- A. baumannii strains.
Published: 2020

27. Distinct Mechanisms of Dissemination of NDM-1 Metallo-β-Lactamase in

Author: Mark D, Adams, Fernando, Pasteran, German M, Traglia, Jasmine, Martinez, Fanny, Huang, Christine, Liu, Jennifer S, Fernandez, Carolina, Lopez, Lisandro J, Gonzalez, Ezequiel, Albornoz, Alejandra, Corso, Alejandro J, Vila, Robert A, Bonomo, and Maria Soledad, Ramirez
Subjects: Acinetobacter baumannii, Argentina, Microbial Sensitivity Tests, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, beta-Lactamases, Anti-Bacterial Agents, Epidemiology and Surveillance, Carbapenems, polycyclic compounds, bacteria, Humans, Genome, Bacterial, Acinetobacter Infections, Plasmids
Abstract: A 4-year surveillance of carbapenem-resistant Acinetobacter spp. isolates in Argentina identified 40 strains carrying bla(NDM-1). Genome sequencing revealed that most were Acinetobacter baumannii, whereas seven represented other Acinetobacter spp. The A. baumannii genomes were closely related, suggesting recent spread. bla(NDM-1) was located in the chromosome of A. baumannii strains and on a plasmid in non-A. baumannii strains. A resistance gene island carrying bla(PER-7) and other resistance determinants was found on a plasmid in some A. baumannii strains.
Published: 2020

28. Genetic Diversity of KPC-ProducingEscherichia coli, Klebsiella oxytoca, Serratia marcescens, andCitrobacter freundiiIsolates from Argentina

Author: Ezequiel Albornoz, Sonia Gomez, Fernando Pasteran, Celeste Lucero, Denise Gisele de Belder, Alejandro Petroni, Diego Faccone, Melina Rapoport, Alejandra Corso, and Adriana E. Rosato
Subjects: 0301 basic medicine, Microbiology (medical), CIENCIAS MÉDICAS Y DE LA SALUD, Klebsiella pneumoniae, medicine.medical_treatment, Blakpc, 030106 microbiology, Immunology, Argentina, Ciencias de la Salud, medicine.disease_cause, Microbiology, beta-Lactamases, 03 medical and health sciences, Plasmid, Enterobacteriaceae, Bacterial Proteins, Drug Resistance, Bacterial, Escherichia coli, medicine, Humans, Serratia marcescens, Pharmacology, Cross Infection, biology, Klebsiella oxytoca, Genetic Variation, Genetic Environment, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, biology.organism_classification, Drug Resistance, Multiple, Citrobacter freundii, Enfermedades Infecciosas, DNA Transposable Elements, Beta-lactamase, Antimicrobial Resistance, Plasmids
Abstract: The predominance of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae was caused by the spread of ST258 clone. In Latin America, KPC was reported in 2006, with the isolation of genetically unrelated K. pneumoniae in Colombia. Since then, the expansion of blaKPC in either K. pneumoniae ST258 or other Enterobacteriaceae (ETB) species was increasingly reported. In this study, we characterized 89 KPC producing Escherichia coli, Klebsiella oxytoca, Serratia marcescens, and Citrobacter freundii that were received between 2010 and 2014. The results revealed that all isolates harbored blaKPC-2. Moreover, the dissemination of KPC by non-K. pneumoniae was mainly caused by the dispersion of ETB mostly genetically unrelated. E. coli is a community pathogen that may serve as the vehicle for the spread of KPC into community settings. Recently, KPC was detected in E. coli ST131, an international epidemic and multidrug-resistant clone. We found that 5/29 KPC-producing E. coli belonged to ST131 and four were blaCTXM-15 producers. The detection of blaKPC in ST131 should be closely monitored to prevent further dissemination. The blaKPC isgenerally located within Tn4401 transposon capable of mobilization through transposition found in plasmids in ST258. Less is known about the diversity of blaKPC genetic elements that disseminate horizontally among other species of ETB. We found that 16/29 E. coli and 2/18 S. marcescens harbored blaKPC-2 in Tn4401a. In 71 isolates, blaKPC-2 was located amidst diverse Tn3-derived genetic elements bearing non-Tn4401 structure. Further studies on the plasmids that encode blaKPC-2 in these clinical isolates may provide additional insight into its transmission mechanisms. Fil: de Belder, Denise Gisele. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Lucero, Celeste. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Rapoport, Melina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Rosato, Adriana. Houston Methodist Research Institute; Estados Unidos Fil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Petroni, Alejandro. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Albornoz, Ezequiel Pablo. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Corso, Alejandra. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina
Published: 2018

29. 945. Bacteremia in Patients with Solid Tumors: Epidemiology, Clinical Features and Risk Factors for Mortality. Results from a Multicenter Study in Argentina

Author: Patricia E Costantini, Diego Torres, Miguel Dictar, Andrea Nenna, Alejandra Valledor, Rosana Jordán, Ana Laborde, Sandra Lambert, José Benso, Alberto Carena, Martín Luck, Agustina Racioppi, Laura Barcan, María José Eusebio, María Luz Gonzalez Ibañez, Lucas Tula, Fernando Pasteran, Alejandra Corso, Melina Rapoport, Marcelo Bronzi, Federico Nicola, Sandra Valle, María Laura Chaves, Graciela Greco, Renata Monge, María Cristina García Damiano, Miriam Blanco, and Fabián Herrera
Subjects: Infectious Diseases, AcademicSubjects/MED00290, Oncology, Poster Abstracts
Abstract: Background Current information regarding bacteriemia in patients with solid tumors is scarce Methods To assess the etiology, clinical features and outcome in patients with solid tumors and bacteremia, we carried out a prospective multicenter study. Episodes of bacteriemia in adult cancer patients in 9 centers, from May 2014 to February 2021, were recorded. To identify factors associated with 30-day mortality, variables with p < 0.05 in univariate analysis were included in a logistic regression model for multivariate analysis Results Three hundred and thirty-two episodes of bacteremia were included, with 51% being women (mean age 59). The state of underlying disease was: recent diagnosis 27%, remission 27%, relapsed 29% and refractory 17%. Seventy-three percent had received chemotherapy in the last 30 days, 25% were receiving steroids. Neutropenia was present in 23% (mean duration 3 days). The most frequent sources were: abdominal 39%, urinary tract 21%, respiratory 15%, catheter 10% and skin and soft tissue 9%. The microorganisms were: Gram negative bacilli (GNB) 67% (Enterobacterales 84%), Gram positive cocci 36% (Staphylococcus aureus 33%) and polimicorbial 11%; 20% were multidrug resistant organisms (MDR-O), being 88% of them GNB (MDR-GNB). ESBL and KPC carbapenemase producing were the most frequent mechanisms of resistance. Mortality at day 7 and day 30 was 16% and 27%, respectively. In the univariate analysis, the risk factors for 30-day mortality were Charlson index, refractory underlying disease, use of steroids, polimicrobial bacteremia, Staphylococcus aureus, GNB resistant to carbapenems, APACHE and Pitt scores, hypotension, respiratory source and ICU admission. In multivariate analysis, risk factors for 30-day mortality were refractory underlying disease, GNB resistant to carbapenems and ICU admission, while 7-day clinical response was associated with lower mortality Conclusion Bacteremia is a serious complication in cancer patients, with high mortality. The state of underlying disease, infection caused by GNB resistant to carbapenems, and the severity of presentation are associated with increased mortality. Our results stress the importance of infection control measures and antibiotic stewardship to prevent colonization with MDR-O Disclosures All Authors: No reported disclosures
Published: 2021

30. Pseudomonas putida group species as reservoirs of mobilizable Tn402-like class 1 integrons carrying blaVIM-2 metallo-β-lactamase genes

Author: Alejandra Corso, María S. Díaz, Adriana S. Limansky, Alejandro M. Viale, Fernando Pasteran, Diego Faccone, Patricia Marchiaro, and Marco A. Brovedan
Subjects: Microbiology (medical), Transposable element, Genetics, Biology, medicine.disease_cause, biology.organism_classification, 16S ribosomal RNA, Microbiology, Pseudomonas putida, Transposition (music), Infectious Diseases, Plasmid, medicine, bacteria, Mobile genetic elements, Molecular Biology, Escherichia coli, Ecology, Evolution, Behavior and Systematics, Transposase
Abstract: The Pseudomonas putida group (P. putida G) is composed of at least 21 species associated with a wide range of environments, including the clinical setting. Here, we characterized 13 carbapenem-resistant P. putida G clinical isolates bearing class 1 integrons/transposons (class 1 In/Tn) carrying blaVIM-2 metallo-β-lactamase gene cassettes obtained from hospitals of Argentina. Multilocus sequencing (MLSA) and phylogenetic analyses based on 16S rDNA, gyrB and rpoD sequences distinguished 7 species among them. blaVIM-2 was found in three different cassette arrays: In41 (blaVIM-2-aacA4), In899 (only blaVIM-2), and In528 (dfrB1-aacA4-blaVIM-2). In41 and In899 were associated with complete tniABQC transposition modules and IRi/IRt boundaries characteristic of the Tn5053/Tn402 transposons, which were designated Tn6335 and Tn6336, respectively. The class 1 In/Tn element carrying In528, however, exhibited a defective tni module bearing only the tniC (transposase) gene, associated with a complete IS6100 bounded with two oppositely-oriented IRt end regions. In some P. putida G isolates including P. asiatica, P. juntendi, P. putida G/II, and P. putida G/V, Tn6335/Tn6336 were carried by pLD209-type conjugative plasmids capable of self-mobilization to P. aeruginosa or Escherichia coli. In other isolates of P. asiatica, P. putida G/II, and P. monteiliieilii, however, these blaVIM-2-containing class 1 In/Tn elements were found inserted into the res regions preceding the tnpR (resolvase) gene of particular Tn21 subgroup members of Tn3 transposons. The overall results reinforce the notion of P. putida G members as blaVIM-2 reservoirs, and shed light on the mechanisms of dissemination of carbapenem resistance genes to other pathogenic bacteria in the clinical setting.
Published: 2021

31. Novel class 1 Integrons and sequence types in VIM-2 and VIM-11-producing clinical strains of Enterobacter cloacae

Author: Celeste Lucero, Diego Faccone, Roberto G. Melano, Alejandro Petroni, Denise Gisele de Belder, Sonia Gomez, Fernando Pasteran, Nathalie Tijet, Alejandra Corso, and Melina Rapoport
Subjects: Male, 0301 basic medicine, Carbapenem, Imipenem, Resistance, Ciencias de la Salud, Integron, Integrons, Aged, 80 and over, Cross Infection, biology, Enterobacteriaceae Infections, Enterobacter, Middle Aged, Enterobacteriaceae, Anti-Bacterial Agents, Infectious Diseases, Female, medicine.drug, DNA, Bacterial, Microbiology (medical), endocrine system, CIENCIAS MÉDICAS Y DE LA SALUD, 030106 microbiology, Microbial Sensitivity Tests, Microbiology, beta-Lactamases, 03 medical and health sciences, Bacterial Proteins, Enterobacter cloacae, Genetics, medicine, Humans, Epidemiología, Typing, Molecular Biology, Ecology, Evolution, Behavior and Systematics, Infant, Newborn, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, biology.organism_classification, 030104 developmental biology, Carbapenems, Vim, biology.protein, Multilocus sequence typing, Multilocus Sequence Typing
Abstract: All VIM-producing Enterobacteriaceae (six Enterobacter cloacae) submitted to the Argentinian Reference Laboratory in Antimicrobial Resistance in the period 2008-13 were characterized. The isolates were referred from 6 nosocomial institutions located in 5 different cities across the country. All isolates showed carbapenem disk diffusion inhibition zones ≤22mm and synergism between a carbapenem disk and EDTA/SMA. The six isolates were PCR positive for blaVIM. Imipenem MICs were ≤1 to 8μg/ml. Typing by PFGE and MLST distinguished six pulsotypes and sequence types with blaVIM located on novel class 1 integron arrays: ECL-1: ST182, In883; ECL-2, ST90, In885; ECL-3, ST88, In346 with blaVIM-11; ECL-4, ST184, In900; ECL-5, ST749-new, In900; ECL-6, ST91 and uncharacterized In. Only ECL-2 was able to transfer blaVIM-2 to E. coli J53 by biparental conjugation. blaVIM was located in plasmids of 53-82Kb and in the chromosome (ECL-1 and ECL-5). The diversity of clones, class 1 integrons, plasmids and location of blaVIM, reveals the plasticity of the genetic elements described and highlights the importance of surveillance programs as tools to identify the transmission of these highly resistant metallo-β-lactamase-producing Enterobacteriaceae. Fil: de Belder, Denise Gisele. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Faccone, Diego Francisco. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tijet, N.. Public Health Ontario; Canadá Fil: Melano, R.. Public Health Ontario; Canadá Fil: Rapoport, Melina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Petroni, Alejandro. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Lucero, Celeste. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina
Published: 2017

32. Aerobic etiology of acute appendicitis in adults. Multicenter study of abdominal sepsis in Argentina

Author: Pablo G, Scapellato, Pedro, Pessacq, Alejandra, Corso, Fernando, Pasteran, Melina, Rapoport, Walter, Vasen, Corina, Nemirovsky, and Aníbal, Calmaggi
Subjects: Adult, Male, lcsh:Immunologic diseases. Allergy, appendicitis, Adolescent, Argentina, lcsh:Medicine, Microbial Sensitivity Tests, Gram-Positive Bacteria, lcsh:Infectious and parasitic diseases, Young Adult, Sepsis, Gram-Negative Bacteria, Humans, lcsh:RC109-216, Prospective Studies, antimicrobial resistance, intra-abdominal infections, peritonitis, Aged, Aged, 80 and over, lcsh:R, Middle Aged, biochemical phenomena, metabolism, and nutrition, Anti-Bacterial Agents, Acute Disease, abdominal sepsis, Intraabdominal Infections, Female, lcsh:RC581-607
Abstract: Antibiotic treatment for acute appendicitis is empirically chosen, based on epidemiological information. Resistance rates are different between regions and there are limited data on the situation in Argentina. As a part of a multicenter, observational study of abdominal infections, we performed the analysis of adult patients diagnosed with appendicitis, enrolled in 16 centers of 5 provinces, between Jan/01/2014 and Jun/30/2015. The aim was to analyze the prevalent aerobic pathogens, their resistance rates and the antimicrobial prescription pattern. On a total of 131 appendicitis cases analyzed, we found 184 aerobic pathogens (1.4 bacteria/episode): Escherichia coli 106 (57.6%), Klebsiella spp 16 (8.7%), Pseudomonas aeruginosa 19 (10.3%), Enterobacter spp. 2 (1%), other Gram negative bacilli 5 (2.7%); Enterococcus spp. 16 (8.7%) and other Gram positive cocci 20 (10.9%). The resistance rate of E. coli and enterobacteria to ampicillin/sulbactam was greater than 34% and greater than 31% to ciprofloxacin. However, the resistance of enterobacteria to piperacillin/tazobactam was 4.8%, to ceftriaxone 9.5%, to amikacin 3.6% and 8.2% to gentamicin. No resistance to carbapenems was found. The choice of quinolones or ampicillin/sulbactam for the treatment of appendicitis should be discouraged in our context, due to the high rates of resistance found in this prevalent etiology. Aminoglycoside-based treatments should be considered, given the findings of high antibiotic susceptibility and their low impact on the induction of resistance.
Published: 2017

33. Characterization of a multidrug resistant Citrobacter amalonaticus clinical isolate harboring blaNDM-1 and mcr-1.5 genes

Author: Diego Faccone, Nathalie Tijet, Sonia Gomez, Fernando Pasteran, Estefania Biondi, Roberto G. Melano, Alejandra Corso, Ezequiel Albornoz, and Miryam Vázquez
Subjects: 0301 basic medicine, Microbiology (medical), Carbapenem, CIENCIAS MÉDICAS Y DE LA SALUD, 030106 microbiology, purl.org/becyt/ford/3.5 [https], Microbiology, BLANDM, Citrobacter amalonaticus, 03 medical and health sciences, CARBAPENEM, Genetics, medicine, Molecular Biology, Gene, Ecology, Evolution, Behavior and Systematics, Citrobacter, biology, CITROBACTER AMALONATICUS, biology.organism_classification, Otras Ciencias Médicas, Multiple drug resistance, COLISTIN, Pediatric patient, 030104 developmental biology, Infectious Diseases, Colistin, MCR-1, purl.org/becyt/ford/3 [https], medicine.drug
Abstract: A multidrug resistant isolate, identified as Citrobacter amalonaticus using MALDI-TOF MS and confirmed by genomic analysis, was recovered from a pediatric patient in a hospital from Buenos Aires, Argentina. By whole-genome sequencing a total of 16 resistance genes were detected, including blaNDM-1 and mcr-1.5. To the best of our knowledge this is the first description of these two genes together in a clinical isolate of the Citrobacter genus. Fil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Albornoz, Ezequiel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Tijet, Nathalie. Public Health Ontario; Canadá Fil: Biondi, Estefania. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Vazquez, Miryam. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Melano, Roberto Gustavo. University of Toronto; Canadá. Public Health Ontario; Canadá Fil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina
Published: 2019

34. Multiple clones of metallo-β-lactamase-producing Acinetobacter ursingii in a children hospital from Argentina

Author: Florencia Martino, Denise Gisele de Belder, Sonia Gomez, Ezequiel Albornoz, Fernando Pasteran, Alejandra Corso, Diego Faccone, Miryam Vázquez, Melina Rapoport, Estefania Biondi, and Veronica Rodrigo
Subjects: 0301 basic medicine, Microbiology (medical), CIENCIAS MÉDICAS Y DE LA SALUD, 030106 microbiology, Argentina, Ciencias de la Salud, BLANDM-1 MLST, Microbial Sensitivity Tests, Aztreonam, Biology, Microbiology, beta-Lactam Resistance, beta-Lactamases, ACINETOBACTER URSINGII, 03 medical and health sciences, chemistry.chemical_compound, Acinetobacter ursingii, Intensive care, Genetics, medicine, Pulsed-field gel electrophoresis, Humans, Epidemiología, Child, Molecular Biology, Phylogeny, Ecology, Evolution, Behavior and Systematics, Cross Infection, Acinetobacter, biochemical phenomena, metabolism, and nutrition, Hospitals, Pediatric, bacterial infections and mycoses, biology.organism_classification, rpoB, BLAIMP-1, Anti-Bacterial Agents, Electrophoresis, Gel, Pulsed-Field, 030104 developmental biology, Infectious Diseases, chemistry, Colistin, bacteria, Multilocus sequence typing, Acinetobacter Infections, Multilocus Sequence Typing, medicine.drug
Abstract: Acinetobacter spp. are opportunistic pathogens being A. baumannii the most frequently identified in nosocomial settings. A. ursingii was mainly described as causing bacteremia and outbreaks in neonatal intensive care units. Ten A. ursingii isolates were recovered from rectal swab screening for carbapenemase-producing bacteria between June 2013 and December 2015 from a children hospital in Argentina. All ten isolates were metallo-β-lactamase-producing, nine were positive for blaIMP-1 and one for blaNDM-1. IMP-positive isolates were also positive for blaOXA-58 gene. All isolates were susceptible to ciprofloxacin, colistin and minocycline, and nine were susceptible to ampicillin-sulbactam and gentamicin. Two A. ursingii displayed high level of resistance to aztreonam associated with blaCTX-M-15 in one isolate, and blaVEB-1 in the other. Eight SmaI-PFGE patterns were recognized. We evaluated the usefulness of Acinetobacter MLST-Pasteur scheme, to analyse A. ursingii isolates, however the rpoB gene was not amplified. A new set of primers were designed for specific amplification and sequencing, allowing the analysis of rpoB gene for this species. New alleles and the sequence types 748, 749, 750, 751, 993, 1186, 1187, and 1189 were included at the Acinetobacter MLST-Pasteur database. Those isolates showing related PFGE patterns were assigned to the same ST. To the best of our knowledge, this is the first report of MBL-producing A. ursingii in Argentina. The inclusion of A. ursingii species to the Acinetobacter MLST-Pasteur scheme allows deeper molecular characterization and a better understanding about the epidemiology of this germen. Fil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Martino, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Albornoz, Ezequiel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Biondi, Estefania. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Vazquez, Miryam. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: Rapoport, Melina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Rodrigo, Veronica. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina Fil: de Belder, Denise Gisele. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina
Published: 2019

35. Modeling Meropenem Treatment, Alone and in Combination with Daptomycin, for KPC-Producing Klebsiella pneumoniae Strains with Unusually Low Carbapenem MICs

Author: Liliana I. Paz, Alejandra Corso, Fernando Pasteran, Adriana E. Rosato, Regina Fernandez, J. Gu, Paula Gagetti, Warren E. Rose, Maryam Fatouraei, and Maria P. Martinez
Subjects: 0301 basic medicine, Staphylococcus aureus, Carbapenem, Klebsiella pneumoniae, 030106 microbiology, Microbial Sensitivity Tests, medicine.disease_cause, Meropenem, beta-Lactamases, Microbiology, 03 medical and health sciences, chemistry.chemical_compound, Bacterial Proteins, Daptomycin, polycyclic compounds, medicine, Experimental Therapeutics, Pharmacology (medical), Therapeutic strategy, Pharmacology, biology, business.industry, Lipopeptide, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, biology.organism_classification, Infectious Diseases, Carbapenems, chemistry, Thienamycins, business, Bacteria, medicine.drug
Abstract: Klebsiella pneumoniae strains producing K. pneumoniae carbapenemase (KPC) cause serious infections in debilitated and immunocompromised patients and are associated with prolonged hospital stays and increased mortality rates. Daptomycin is a lipopeptide used against Staphylococcus aureus infection and considered inactive against Gram-negative bacteria. We investigated the effectiveness of a daptomycin-meropenem combination by synergy kill curve and a pharmacokinetic/pharmacodynamic model. The combination may represent a novel therapeutic strategy against infections caused by KPC-producing K. pneumoniae strains.
Published: 2016

36. Resistencia a colistín mediado por el gen mcr-1 identificado en cepas de Escherichia coli y Klebsiella pneumoniae. Primeros reportes en el Perú

Author: José Maria Olivo López, Ruth Giovanna Ugarte Silva, Fernando Pasteran, Zaida Patricia Sahuanay Blácido, Alejandra Corso, and Ezequiel Albornoz
Subjects: 0301 basic medicine, microbial, Medicine (General), Klebsiella pneumoniae, Farmacorresistencia microbiana, Multiresistant bacteria, medicine.disease_cause, Microbiology, Colistin resistance, 03 medical and health sciences, Minimum inhibitory concentration, R5-920, 0302 clinical medicine, medicine, Escherichia coli, 030212 general & internal medicine, General Environmental Science, biology, Colistin, Colistín, biochemical phenomena, metabolism, and nutrition, biology.organism_classification, 030104 developmental biology, Drug resistance, Medicine, bacteria, General Earth and Planetary Sciences, hormones, hormone substitutes, and hormone antagonists, medicine.drug
Abstract: Introducción. Ante la aparición de reportes de la presencia del gen mcr-1 y su posible diseminación por plásmidos en los países de la región y dado que este gen confiere resistencia a colistín, fármaco que es la última línea de tratamiento contra bacterias multirresistentes, es importante conocer su presencia en nuestro país en microorganismos que lo expresen. Métodos. Se realizó un estudio descriptivo y transversal. Se incluyeron microorganismos aislados de urocultivos de pacientes ambulatorios de un centro de salud privado en Lima, Perú, en agosto del año 2017. De 326 urocultivos positivos se seleccionaron 10 aislamientos entre cepas de Escherichia coli y Klebsiella pneumoniae que presentaron concentración mínima inhibitoria ≥4μg/mL (interpretado como resistente para colistín) por el sistema automatizado Microscan Walkaway 96 plus. Se utilizaron los siguientes métodos: colistín agar spot, predifusión con tabletas de colistín, microdilución en caldo colistin y PCR para el gen mcr-1. Resultados. Se determinó que 7 aislamientos, todas Escherichia coli, expresaron la presencia del gen mcr-1 por PCR, el cual confiere resistencia plasmídica a polipéptidos. De las cepas restantes, dos Escherichia coli y una Klebsiella pneumoniae, resultaron positivos para resistencia a colistín en las pruebas fenotípicas pero no en la PCR para gen mcr-1 lo cual sugiere un mecanismo de resistencia a colistín no asociado a gen mcr-1. Conclusiones. Se obtuvieron 7 aislamientos de Escherichia coli resistentes a colistín y con expresión del gen mcr-1., Introduction. Given the appearance of reports of the presence of the mcr-1 gene and its possible dissemination by plasmids in the countries of the region and given that this gene confers resistance to colistin, the drug that is the last line of treatment against multiresistant bacteria, it is important to know its presence in our country in microorganisms that express it. Methods. Descriptive and cross-sectional study was carried out. Microorganisms isolated from urine culture of outpatients from a private health center in Lima, Peru, were included in august 2017. Out of 326 positive urine cultures, 10 isolates were selected between strains of Escherichia coli and Klebsiella pneumoniae that had a minimum inhibitory concentration ≥4μg/mL (interpreted as resistant for colistín) by the automated system Microscan Walkaway 96 plus. The following methods were used: colistin agar spot, prediffusion with colistin tablets, microdilution in colistin broth and PCR for the mcr-1 gene. Results. It was determined that 7 isolates, all Escherichia coli, expressed the presence of the mcr-1 gene by PCR, which confers plasmid resistance to polypeptides. Of the remaining strains, two Escherichia coli and one Klebsiella pneumoniae, were positive for resistance to colistin in the phenotypic tests but not in the PCR for mcr-1 gene, which suggests a mechanism of colistin resistance not associated with the mcr-1 gene. Conclusions. Seven isolates of Escherichia coli resistant to colistin and with expression of the mcr-1 gene were obtained.
Published: 2018

37. In vivo horizontal dissemination of the blaKPC-2 gene carried on diverse genetic platforms among clinical isolates of Enterobacteriaceae

Author: Mario Daniel Rapoport, I. Herrero, Diego Faccone, Celeste Lucero, Sonia Gomez, Fernando Pasteran, Florencia Martino, A. Rodriguez, A. Di Martino, Maria Sol Anchordoqui, Alejandra Corso, and Denise Gisele de Belder
Subjects: Microbiology (medical), Genetics, Salud Ocupacional, CIENCIAS MÉDICAS Y DE LA SALUD, biology, Klebsiella pneumoniae, Immunology, Ciencias de la Salud, HORIZONTAL DISSEMINATION, Klebsiella oxytoca, biology.organism_classification, medicine.disease_cause, Microbiology, Enterobacteriaceae, KPC-2, Citrobacter freundii, TN4401A, Plasmid, ENTEROBACTERIACEAE, medicine, Immunology and Allergy, Enterobacter cloacae, Escherichia coli, Southern blot
Abstract: This study investigated the molecular characteristics of six blaKPC-positive Enterobacteriaceae recovered from three patients in Argentina. Antimicrobial susceptibility testing was performed following Clinical and Laboratory Standards Institute (CLSI) 2014 recommendations. Molecular characterisation of the isolates was performed by biparental conjugation, PCR, sequencing, S1 nuclease restriction, and Southern blot hybridisation with a blaKPC probe using standard protocols and conditions. The isolates studied were as follows. Case 1: Escherichia coli (ECO-P1) and Klebsiella pneumoniae (KPN-P1) isolated from a rectal swab harboured blaKPC-2 in transposon Tn4401a on non-typeable and non-conjugative plasmids. Case 2: Enterobacter cloacae (ECL-P2) and K. pneumoniae (KPN-P2) were isolated from two blood cultures. blaKPC-2 was found in a novel genetic variant of ISKpn8-blaKPC-2-ISKpn6-like on conjugative plasmids of IncL/M type. Case 3, Citrobacter freundii (CFR-P3) and Klebsiella oxytoca (KOX-P3) were isolated from skin and skin-structure infection. The blaKPC gene was detected on ISKpn8-ΔblaTEM-blaKPC-2-ISKpn6-like located on an IncA/C conjugative plasmid. CFR-P3 and KOX-P3 harboured blaPER-2 in addition to the blaKPC gene. In conclusion, we document the horizontal dissemination of blaKPC-2 from diverse Enterobacteriaceae clinical isolates with different genetic backgrounds. This is the first report of E. coli harbouring blaKPC associated with Tn4401a in Argentina. Fil: Anchordoqui, Maria Sol. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: de Belder, Denise Gisele. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Lucero, C.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Rapoport, Mario Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Rodriguez, A.. Clínica y Maternidad Suizo Argentina; Argentina Fil: Di Martino, A.. Sanatorio Mitre; Argentina Fil: Martino, F.. Clínica y Maternidad Suizo Argentina; Argentina Fil: Herrero, I.. Hospital Municipal de Urgencias; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Corso, Alejandra. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina
Published: 2015

38. Molecular characteristics of mcr-1-carrying plasmids and new mcr-1 variant recovered from polyclonal clinical Escherichia coli from Argentina and Canada

Author: Alejandro Petroni, Alejandra Corso, Nathalie Tijet, Paola Ceriana, Christine Seah, Ezequiel Albornoz, Melina Rapoport, Fernando Pasteran, Diego Faccone, and Roberto G. Melano
Subjects: 0301 basic medicine, Ciencias de la Salud, lcsh:Medicine, medicine.disease_cause, Pathology and Laboratory Medicine, Polymerase Chain Reaction, Geographical locations, law.invention, Database and Informatics Methods, Plasmid, law, Antibiotics, Mobile Genetic Elements, Genotype, Medicine and Health Sciences, lcsh:Science, Polymerase chain reaction, Escherichia coli Infections, Escherichia Coli, Multidisciplinary, Antimicrobials, Escherichia coli Proteins, Drugs, Genomics, Anti-Bacterial Agents, Bacterial Pathogens, COLISTIN, Experimental Organism Systems, Medical Microbiology, Prokaryotic Models, purl.org/becyt/ford/3 [https], Pathogens, Sequence Analysis, hormones, hormone substitutes, and hormone antagonists, Plasmids, Research Article, Transposable element, DNA, Bacterial, Escherichia, Canada, China, CIENCIAS MÉDICAS Y DE LA SALUD, Asia, COLI, Sequence analysis, Bioinformatics, 030106 microbiology, Argentina, Sequence Databases, Microbial Sensitivity Tests, Biology, Research and Analysis Methods, Microbiology, Bacterial genetics, purl.org/becyt/ford/3.3 [https], 03 medical and health sciences, Model Organisms, Genetic Elements, Enterobacteriaceae, Microbial Control, Drug Resistance, Bacterial, medicine, Genetics, Humans, Amino Acid Sequence, Polymyxins, Escherichia coli, Microbial Pathogens, Pharmacology, Salud Ocupacional, Sequence Homology, Amino Acid, Bacteria, lcsh:R, Gut Bacteria, Organisms, Transposable Elements, Genetic Variation, Biology and Life Sciences, Sequence Analysis, DNA, South America, Ethanolaminephosphotransferase, Biological Databases, North America, MCR, MCR-1, lcsh:Q, People and places, Sequence Alignment, PLASMID
Abstract: Tijet N. and Faccone D. contributed equally to this work.We have characterized nine mcr-1-harboring plasmids from clinical Escherichia coli isolatespreviously described in Argentina and Canada. Three of these plasmids carried a mcr-1-variantcalled here mcr-1.5. All these E. coli isolates were not clonally related and were recoveredin different years and locations. However, their mcr-1-harboring plasmids showed highidentity among them and to others characterized in other countries, which strongly suggeststhat this plasmid-type is playing an important role in spreading this mechanism of resistanceto polymyxins. Fil: Tijet, Nathalie. Public Health Ontario Laboratory; Canadá Fil: Faccone, Diego Francisco. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rapoport, Melina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Seah, Christine. Public Health Ontario Laboratory; Canadá Fil: Pasteran, Fernando. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Ceriana, Paola. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Albornoz, Ezequiel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Petroni, Alejandro. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Melano, Roberto G.. Public Health Ontario Laboratory; Canadá. University of Toronto; Canadá
Published: 2017

39. Isolation of five Enterobacteriaceae species harbouring blaNDM-1 and mcr-1 plasmids from a single paediatric patient

Author: Alejandra Corso, Nathalie Tijet, Florencia Martino, V. Rodrigo, D. De Belder, Estefania Biondi, Roberto G. Melano, Sonia Gomez, Fernando Pasteran, Eva Heinz, Nicholas R. Thomson, Melina Rapoport, Alejandro Petroni, Diego Faccone, and Miryam Vázquez
Subjects: Klebsiella pneumoniae, Drug resistance, Pathology and Laboratory Medicine, Biochemistry, Mass Spectrometry, Klebsiella Pneumoniae, Analytical Chemistry, Spectrum Analysis Techniques, Plasmid, Klebsiella, Mobile Genetic Elements, Medicine and Health Sciences, Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry, Data Management, 0303 health sciences, Multidisciplinary, Antimicrobials, Broth microdilution, Drugs, Phylogenetic Analysis, Genomics, Bacterial Pathogens, Citrobacter freundii, Nucleic acids, Phylogenetics, Chemistry, Medical Microbiology, Physical Sciences, Medicine, Pathogens, Anatomy, Research Article, Plasmids, Computer and Information Sciences, Forms of DNA, Science, Biology, Research and Analysis Methods, Microbiology, 03 medical and health sciences, Genetic Elements, Antibiotic resistance, Enterobacteriaceae, Microbial Control, Genetics, Evolutionary Systematics, Microbial Pathogens, Taxonomy, 030304 developmental biology, Pharmacology, Evolutionary Biology, Bacteria, Biology and life sciences, 030306 microbiology, Organisms, Rectum, DNA, biology.organism_classification, Gastrointestinal Tract, MCR-1, Antimicrobial Resistance, Digestive System, Enterobacter cloacae
Abstract: In Argentina, NDM metallo-β-lactamase was first reported in 2013. By now, it has disseminated throughout the country in diverse Gram negative bacteria. Here, we report the case of a paediatric patient that underwent a 1-year hospitalisation due to erythrodermic psoriasis in 2014 and received multiple antimicrobial treatments. During his stay, five isolates were obtained from rectal swabs (rs) or blood culture (bc) suspicious of carbapenemase production: a K. quasipneumoniae subsp. quasipneumoniae (rs), Citrobacter freundii (rs), Escherichia coli (bc), Enterobacter cloacae (rs), and a Serratia marcescens (bc). The isolates were studied with broth microdilution, biparental conjugation and plasmid and whole genome sequencing (Illumina). All isolates harboured an 138,998-bp type 1 IncC plasmid that carried blaNDM-1, bleMBL, blaCMY-6, rmtC, aac(6’)-Ib, and sul1 resistance genes. Additionally, the blaNDM-plasmids contained ISKpn8 an insertion sequence previously described as associated only to blaKPC. One isolate, a colistin-resistant E. coli, also carried a mcr-1-containing an IncI2 plasmid, which did not harbour additional resistance. The whole genome of K. quasipneumoniae subsp. quasipneumoniae isolate was fully sequenced. This isolate harboured, additionally to blaNDM, three plasmid-mediated quinolone resistance genes: qnrB4, qnrB52 and aac(6’)-Ib-cr1. The E. cloacae isolate also harboured qnrA1. These findings alert to the underestimated horizontal dissemination of multidrug-resistant plasmids limiting treatment options with last resort antimicrobials.
Published: 2019

40. Increased Detection of Carbapenemase-Producing Enterobacterales Bacteria in Latin America and the Caribbean during the COVID-19 Pandemic

Author: Genara Romero Thomas, Alejandra Corso, Fernando Pasterán, Justina Shal, Aldo Sosa, Marcelo Pillonetto, Renata Tigulini de Souza Peral, Juan Carlos Hormazábal, Pamela Araya, Sandra Yamile Saavedra, Mariá Victoria Ovalle, María Antonieta Jiménez Pearson, Grettel Chanto Chacón, Eric Carbon, Carmen Julia Mazariegos Herrera, Selene del Carmen González Velásquez, Carolina Satan-Salazar, Fernando Villavicencio, Nancy Melgarejo Touchet, Sofía Busignani, Maritza Mayta-Barrios, Juan Ramírez-Illescas, Mariana López Vega, Cristina Mogdasy, Verónica Rosas, Nuris Salgado, Rodolfo Quiroz, Nathalie El-Omeiri, Marcelo Fabián Galas, Pilar Ramón-Pardo, and Roberto Gustavo Melano
Subjects: COVID-19, respiratory infections, severe acute respiratory syndrome coronavirus 2, SARS-CoV-2, SARS, coronavirus disease, Medicine, Infectious and parasitic diseases, RC109-216
Abstract: During 2020–2021, countries in Latin America and the Caribbean reported clinical emergence of carbapenemase-producing Enterobacterales that had not been previously characterized locally, increased prevalence of carbapenemases that had previously been detected, and co-production of multiple carbapenemases in some isolates. These increases were likely fueled by changes related to the COVID-19 pandemic, including empirical antibiotic use for potential COVID-19–related bacterial infections and healthcare limitations resulting from the rapid rise in COVID-19 cases. Strengthening antimicrobial resistance surveillance, epidemiologic research, and infection prevention and control programs and antimicrobial stewardship in clinical settings can help prevent emergence and transmission of carbapenemase-producing Enterobacterales.
Published: 2022
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41. Triton Hodge Test: Improved Protocol for Modified Hodge Test for Enhanced Detection of NDM and Other Carbapenemase Producers

Author: Guillermo Bahr, Lisandro J González, Alejandro J. Vila, Ezequiel Albornoz, Fernando Pasteran, and Alejandra Corso
Subjects: 0301 basic medicine, Microbiology (medical), Ertapenem, A lipoprotein, Carbapenem, Octoxynol, Otras Ciencias Biológicas, 030106 microbiology, Detergents, Test sensitivity, Microbial Sensitivity Tests, NDM, Biology, beta-Lactams, Meropenem, Sensitivity and Specificity, beta-Lactamases, Microbiology, Ciencias Biológicas, purl.org/becyt/ford/1 [https], 03 medical and health sciences, Membrane anchoring, chemistry.chemical_compound, Bacterial Proteins, Gram-Negative Bacteria, medicine, Humans, CARBAPENEM RESISTANCE, purl.org/becyt/ford/1.6 [https], Bacteriology, OXA, Antimicrobial, Anti-Bacterial Agents, KPC, 030104 developmental biology, chemistry, New delhi, Thienamycins, METALLO-BETA-LACTAMASE, CIENCIAS NATURALES Y EXACTAS, medicine.drug
Abstract: Accurate detection of carbapenemase-producing Gram-negative bacilli is of utmost importance for the control of nosocomial spread and the initiation of appropriate antimicrobial therapy. The modified Hodge test (MHT), a carbapenem inactivation assay, has shown poor sensitivity in detecting the worldwide spread of New Delhi metallo--lactamase (NDM). Recent studies demonstrated that NDM is a lipoprotein anchored to the outer membrane in Gram-negative bacteria, unlike all other known carbapenemases. Here we report that membrane anchoring of -lactamases precludes detection of carbapenemase activity by the MHT. We also show that this limitation can be overcome by the addition of Triton X-100 during the test, which allows detection of NDM. We propose an improved version of the assay, called the Triton Hodge test (THT), which allows detection of membrane- bound carbapenemases with the addition of this nonionic surfactant. This test was challenged with a panel of 185 clinical isolates (145 carrying known carbapenemase-encoding genes and 40 carbapenemase nonproducers). The THT displayed test sensitivity of>90% against NDM-producing clinical isolates, while improving performance against other carbapenemases. Ertapenem provided the highest sensitivity (97 to 100%, depending on the type of carbapenemase), followed by meropenem (92.5 to 100%). Test specificity was not affected by the addition of Triton (87.5% and 92.5% with ertapenem and meropenem, respectively). This simple inexpensive test confers a large improvement to the sensitivity of the MHT for the detection of NDM and other carbapenemases. Fil: Pasteran, Fernando. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Gonzalez, Lisandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina Fil: Albornoz, Ezequiel Pablo. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bahr, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina Fil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina Fil: Corso, Alejandra. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina
Published: 2016

42. Performance of a PCR assay for the rapid identification of the Klebsiella pneumoniae ST258 epidemic clone in Latin American clinical isolates

Author: Diego Faccone, Mario Daniel Rapoport, ReLAVRA-Group, Sonia Gomez, Fernando Pasteran, Alejandro Petroni, N. Piergrossi, Alejandra Corso, and Denise Gisele de Belder
Subjects: 0301 basic medicine, Microbiology (medical), clone (Java method), PRP, Latin Americans, CIENCIAS MÉDICAS Y DE LA SALUD, Klebsiella pneumoniae, 030106 microbiology, Pcr assay, PILV-L, Ciencias de la Salud, Biology, Microbiology, Polymerase Chain Reaction, beta-Lactamases, purl.org/becyt/ford/3.3 [https], 03 medical and health sciences, Bacterial Proteins, Genetics, Pulsed-field gel electrophoresis, Humans, Typing, Molecular Biology, Gene, ST258 DETECTION, Ecology, Evolution, Behavior and Systematics, South America, biology.organism_classification, KLEBSIELLA PNEUMONIAE, Virology, Klebsiella Infections, Enfermedades Infecciosas, Infectious Diseases, BLAKPC, Multilocus sequence typing, purl.org/becyt/ford/3 [https]
Abstract: The worldwide dissemination of Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae ST258 demands a rapid PCR-based typing method to detect unique genes of the ST258 clone. This study evaluates a PCR developed by Adler et al. (2014) for the detection of ST258 in K. pneumoniae clinical isolates centered on the identification of the pilv-I and prp genes. We tested 143 clinical isolates from Argentina (n = 109), Chile (n = 1), Colombia (n = 1), Costa Rica (n = 2), Ecuador (n = 5), El Salvador (n = 2), Nicaragua (n = 5), Panamá (n = 2), Paraguay (n = 2), Perú (n = 3) and Trinidad and Tobago (n = 11) recovered from 2006 to 2015. blaKPC, pilv-l and prp genes were detected by PCR and sequenced by standard procedures. ST258 and non-ST258 were defined by PFGE and/or MLST. Isolates were grouped according to PFGE patterns: 58 were compatible with ST258 (group 1) and 85 with non-ST258 (group 2). MLST study was done on an arbitrary selection of isolates. The pilv-l gene was present only in ST258 isolates, regardless of the presence of the blaKPC gene. Results for the prp gene were variable. Its presence did not define ST258. The pilv-I PCR had a sensitivity and specificity of 100%, respectively, for the detection of ST258 in the isolates under investigation. Given our findings, the pilv-I PCR could replace more time and resource consuming methods, allowing for more rapid detection of the circulating high risk K. pneumoniae clone ST258 in Latin American (LA) countries. Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Rapoport, Mario Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Piergrossi, N.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Pasteran, Fernando. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: de Belder, Denise Gisele. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: ReLAVRA-Group. No especifica; Fil: Petroni, A.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Corso, A.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina
Published: 2016

43. Bacteremia Due to Escherichia coli With the Plasmid-Mediated Colistin Resistance (COL-R) mcr-1 Gene

Author: Hugo Pagella, Cynthia V Rivero, Andrea Vila, Fernando Pasteran, Mariana Chumbita, Juan Ignacio Dapás, and Alejandra Corso
Subjects: business.industry, medicine.disease_cause, medicine.disease, Colistin resistance, Microbiology, Infectious Diseases, Plasmid, Oncology, Bacteremia, medicine, Colistin, MCR-1, business, Escherichia coli, Gene, medicine.drug
Published: 2016

44. Descripción clínica y epidemiológica de un brote nosocomial por Klebsiella pneumoniae productora de KPC en Buenos Aires, Argentina

Author: Ezequiel Córdova, Fernando Pasteran, María I. Lespada, Nora Gómez, Viviana Oviedo, and Claudia Rodríguez-Ismael
Subjects: Microbiology (medical)
Abstract: Resumen Introduccion Klebsiella pneumoniae (K. pneumoniae) productora de carbapenemasa tipo KPC (Kpn-KPC) representa un patogeno emergente, con elevada capacidad de diseminacion nosocomial. El objetivo del presente estudio es describir las caracteristicas clinicoepidemiologicas de un brote nosocomial por Kpn-KPC en Buenos Aires, Argentina. Metodos Estudio descriptivo y prospectivo. Se registraron los aspectos clinicoepidemiologicos de pacientes con infeccion por Kpn-KPC (agosto de 2009 a julio de 2010). Se determino la sensibilidad a los antimicrobianos mediante antibiograma por disco-difusion y por metodo automatizado (Vitek® 2 C-bioMerieux). La busqueda de carbapenemasa tipo KPC se realizo con la prueba de inhibicion con 3-aminofenil-boronico (APB) y se confirmo su presencia por reaccion en cadena de la polimerasa (PCR, por sus siglas en ingles). Se realizo tipificacion molecular de las cepas aisladas por electroforesis en campo pulsado (PFGE, por sus siglas en ingles). Resultados Se registraron 27 casos de infeccion por Kpn-KPC (sala de cirugia general: n = 8; clinica medica: n = 6; unidad de cuidados intensivos: n = 5; sala de emergencia: n = 4; otras: n = 4). Todos los aislamientos de Kpn-KPC pertenecieron a un mismo clon (ST258). Los sitios de infeccion fueron: tracto urinario (63%), tracto respiratorio (15%), abdomen (15%), sangre (7%) y hueso (4%). Todos los aislamientos de KPn-KPC fueron solamente sensibles a tigeciclina y colistina. Tratamiento empirico inadecuado: 63%. Tratamiento efectivo dirigido: colistina (74%), tigeciclina (4%), tigeciclina + colistina (22%). Mortalidad global: 59% (atribuible: 26%). Cultivos de vigilancia (hisopados) positivos: 7/70 (10%). Conclusiones Se describe la emergencia de un brote nosocomial de Kpn-KPC en Buenos Aires, con alta capacidad de diseminacion y elevada mortalidad. La implementacion de medidas de control de infecciones es fundamental para reducir la transmision nosocomial de Kpn-KPC.
Published: 2012

45. Capacidad de los laboratorios nacionales de referencia en Latinoamérica para detectar mecanismos de resistencia emergentes

Author: Marcelo Galas, Carlos Vay, Pilar Ramon Pardo, Paola Ceriana, Marta Tokumoto, Leonor Guerriero, Raquel Callejo, Jorgelina Smayevsky, Ezequiel Tuduri, Fernando Pasteran, Monica Prieto, Jorge Matheu Álvarez, Alejandra Corso, and Horacio Ángel Lopardo
Subjects: Public Health, Environmental and Occupational Health
Abstract: OBJETIVO: Evaluar la capacidad de 17 laboratorios nacionales de referencia que participan en el Programa Latinoamericano de Control de Calidad en Bacteriologia y Resistencia a los Antimicrobianos (LA-EQAS) para detectar mecanismos de resistencia emergentes, a saber: resistencia de enterobacterias a carbapenemes por presencia de Klebsiella pneumoniae carbapenemasa (KPC); resistencia de enterobacterias a carbapenemes por presencia de metalobetalactamasas (MBL) tipo IMP, y resistencia intermedia a vancomicina de aislamientos de Staphylococcus aureus (VISA). METODOS: Se enviaron los siguientes tres aislamientos a los 17 laboratorios participantes del LA-EQAS: Klebsiella pneumoniae OPS-161 productor de KPC, Enterobacter cloacae OPS-166 productor de IMP y S. aureus OPS-165 con resistencia intermedia a vancomicina. Se evaluo la interpretacion de las pruebas de sensibilidad y deteccion del mecanismo de resistencia y el tamano de los halos de inhibicion (metodo de difusion por discos) o valor de la concentracion inhibitoria minima (CIM). RESULTADOS: La concordancia en la deteccion de los mecanismos de resistencia fue de 76,4%, 73,3% y 66,7% con respecto a la cepas K. pneumoniae OPS-161, E. cloacae OPS-166 y S. aureus OPS-165, respectivamente. La concordancia entre las zonas de inhibicion obtenidas por los laboratorios participantes y los rangos establecidos por el laboratorio coordinador fue aceptable en los tres aislamientos, ya que alcanzo 90,8%, 92,8% y 88,9%, respectivamente, para cada cepa. CONCLUSIONES: La concordancia global en la deteccion de los mecanismos de resistencia KPC, MBL y VISA fue de 72,1%. Consideramos que los laboratorios nacionales de referencia de America Latina son capaces de reconocer estos mecanismos de resistencia emergentes y se espera que en el futuro la concordancia alcance su nivel maximo.
Published: 2011

46. First Case of Human Infection Due to Pseudomonas fulva , an Environmental Bacterium Isolated from Cerebrospinal Fluid

Author: Miryam Vázquez, Marisa Turco, Marisa Almuzara, Carlos Vay, Eduardo L. Lopez, Naoto Tanaka, Melina Rapoport, Maria Soledad Ramirez, Fernando Pasteran, and Adriana Procopio
Subjects: DNA, Bacterial, Microbiology (medical), Molecular Sequence Data, Context (language use), Microbial Sensitivity Tests, Case Reports, Integron, DNA, Ribosomal, beta-Lactamases, Integrons, Meningitis, Bacterial, Microbiology, Cerebrospinal fluid, Bacterial Proteins, Pseudomonas, RNA, Ribosomal, 16S, medicine, Humans, Pseudomonas Infections, Cerebrospinal Fluid, biology, Pseudomonas fulva, Sequence Analysis, DNA, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, biology.organism_classification, medicine.disease, Virology, Anti-Bacterial Agents, Child, Preschool, biology.protein, Female, Bacterial meningitis, Meningitis, Bacteria
Abstract: We report the first case of human infection due to Pseudomonas fulva. P. fulva caused acute meningitis following the placement of a drainage system in a 2-year-old female. Additionally, the isolate displayed a VIM-2 carbapenemase in a class 1 integron context.
Published: 2010

47. Widespread dispersion of the resistance element tet(B)::ISCR2 in XDR Acinetobacter baumannii isolates

Author: Hernan Rodríguez, Daniela Centrón, Marisa Almuzara, Nora Gómez, Sabrina Montaña, Fernando Pasteran, Maria Soledad Ramirez, M. Pennini, Lucía Gulone, Elisabet Vilacoba, Adriana Sucari, German Matias Traglia, and A Fernández
Subjects: 0301 basic medicine, Acinetobacter baumannii, Epidemiology, Tetracycline, 030106 microbiology, Argentina, Short Report, Minocycline, Drug resistance, Polymerase Chain Reaction, Microbiology, 03 medical and health sciences, Antibiotic resistance, stomatognathic system, Bacterial Proteins, medicine, polycyclic compounds, Humans, biology, Nosocomial pathogens, Tetracycline Resistance, Sequence Analysis, DNA, biochemical phenomena, metabolism, and nutrition, biology.organism_classification, Hospitals, Anti-Bacterial Agents, Infectious Diseases, medicine.drug, Acinetobacter Infections
Abstract: SUMMARYAcinetobacter baumannii is a significant nosocomial pathogen often associated with extreme drug resistance (XDR). In Argentina, isolates of A. baumannii resistant to tetracyclines have accounted for more than 40% of drug-resistant isolates in some hospitals. We have previously reported the dispersion of the tet(B) resistance element associated with the ISCR2 transposase in epidemiologically unrelated A. baumannii isolates recovered from 1983 to 2011. This study extends this surveillance to 77 recent (2009–2013) XDR A. baumannii isolates with different levels of minocycline susceptibility. Isolates were examined by a pan-PCR assay, which showed six different amplification patterns, and specific PCRs were used for the confirmation of the the ΔISCR2-tet(B)-tet(R)-ISCR2 element. The tet(B) gene was present in 66 isolates and the ISCR2 element in 68 isolates; the tet(B) gene was associated with ISCR2 in all tet(B)-positive isolates. We conclude that this element is widespread in XDR A. baumannii isolates from Argentina and could be responsible for the emergence of tetracycline resistance in recent years.
Published: 2015

48. Simplified Protocol for Carba NP Test for Enhanced Detection of Carbapenemase Producers Directly from Bacterial Cultures

Author: Nathalie Tijet, Roberto G. Melano, Fernando Pasteran, and Alejandra Corso
Subjects: Microbiology (medical), Bacilli, Bacteriological Techniques, Gram-negative bacteria, Microbiological culture, biology, Bacteriology, biochemical phenomena, metabolism, and nutrition, biology.organism_classification, bacterial infections and mycoses, Sensitivity and Specificity, beta-Lactamases, Microbiology, Bacterial protein, Bacterial Proteins, Gram-Negative Bacteria, Humans
Abstract: We compared carbapenemase detection among 266 Gram-negative bacilli (161 carbapenemase producers) using the Carba NP tests issued by the CLSI (CNPt-CLSI) and a novel protocol (CNPt-direct) designed for carbapenemase detection direct from bacterial cultures (instead of bacterial extracts required by the CLSI tests). The specificities were comparable (100%), but the CNPt-direct was more sensitive (98% versus 84%). The CNPt-direct was easier to perform due to the direct use of colonies and offered a more robust detection of carbapenemase producers.
Published: 2015

49. Evaluation of the Blue-Carba Test for Rapid Detection of Carbapenemases in Gram-Negative Bacilli

Author: Melina Rapoport, Celeste Lucero, Alejandra Corso, Sonia Gomez, Fernando Pasteran, Omar Veliz, Paola Ceriana, and Ezequiel Albornoz
Subjects: Microbiology (medical), BLUE CARBA TEST, Imipenem, Bacilli, Gram-negative bacteria, Microbiological culture, Lysis, CIENCIAS MÉDICAS Y DE LA SALUD, CARBAPENEMASAS, DETECCIÓN, GRAM NEGATIVOS, Ciencias de la Salud, Microbial Sensitivity Tests, beta-Lactam Resistance, beta-Lactamases, Microbiology, purl.org/becyt/ford/3.3 [https], Bacterial Proteins, Gram-Negative Bacteria, medicine, Humans, Letters to the Editor, biology, Inoculation, Chemistry, Gram negative bacilli, biology.organism_classification, In vitro, Anti-Bacterial Agents, Bacterial Typing Techniques, Enfermedades Infecciosas, purl.org/becyt/ford/3 [https], Gram-Negative Bacterial Infections, medicine.drug
Abstract: The Blue-Carba test (BCT) is a biochemical test for rapid (2 h)detection of carbapenemase production in Gram-negative bacillidirectly from bacterial culture . It is based on the in vitrohydrolysis of imipenem by bacterial colonies (direct inoculationwithout prior lysis), which is detected by changes in pH valuesrevealed by the indicator bromothymol blue (blue to green/yellowor green to yellow). It was reported to be 100% sensitive andspecific for Enterobacteriaceae, Pseudomonasspp., and Acinetobacterspp. harboring carbapenemases . We evaluated a simplifiedprotocol of the BCT against various Gram-negative species, includingcombinations of bacterial species/resistance mechanismsthat were not previously evaluated. Fil: Pasteran, Fernando. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Veliz, Omar. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Ceriana, Paola. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Lucero, María Celeste. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Rapoport, Melina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Albornoz, Ezequiel Pablo. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina Fil: Corso, Alejandra. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentina
Published: 2015

50. Emergence of NDM-1-producing Klebsiella pneumoniae in Guatemala

Author: Pilar Ramon-Pardo, Jorge Matheu, Ezequiel Albornoz, Enrique Arbizú, Sonia Gomez, Fernando Pasteran, Laura Valenzuela, Diego Faccone, Pavela Estrada, Claudia Valenzuela, Yeraldine Calderón, Melissa Morales, Alejandra Corso, and Leonor Guerriero
Subjects: Pharmacology, Microbiology (medical), Infectious Diseases, Geography, biology, Klebsiella pneumoniae, Ethnology, Pharmacology (medical), Gene transfer, biology.organism_classification
Abstract: Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas (INEI)-ANLIS ‘Dr. Carlos G. Malbran’, Ciudad Autonoma de Buenos Aires, Argentina; Seccion Bacteriologia, UCREVE/ Laboratorio Nacional de Salud, Ciudad de Guatemala, Guatemala; Hospital Infantil de Infectologia y Rehabilitacion, Ciudad de Guatemala, Guatemala; Hospital General San Juan de Dios, Ciudad de Guatemala, Guatemala; Alert and Response and Epidemic Diseases, Pan American Health Organization/World Health Organization, Washington, DC, USA
Published: 2012

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