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Objectives To explore the in vitro antimicrobial susceptibility among clinically important Gram-negative bacteria (GNB) in Taiwan. Methods From 2016 through 2018, a total of 5458 GNB isolates, including Escherichia coli (n = 1545), Klebsiella pneumoniae (n = 1255), Enterobacter species (n = 259), Pseudomonas aeruginosa (n = 1127), Acinetobacter baumannii complex (n = 368), and Stenotrophomonas maltophilia (n = 179), were collected. The susceptibility results were summarized by the breakpoints of minimum inhibitory concentration (MIC) of CLSI 2020, EUCAST 2020 (for colistin), or published articles (for ceftolozane/tazobactam). The resistance genes among multidrug-resistant (MDR) or extensively drug-resistant (XDR)-GNB were investigated by multiplex PCR. Results Significantly higher rates of non-susceptibility (NS) to ertapenem and carbapenemase production, predominantly KPC and OXA-48-like beta-lactamase, were observed in Enterobacterales isolates causing respiratory tract infection than those causing complicated urinary tract or intra-abdominal infection (12.7%/3.44% vs. 5.7%/0.76% or 7.7%/0.97%, respectively). Isolates of Enterobacter species showed higher rates of phenotypic extended-spectrum β-lactamase and NS to ertapenem than E. coli or K. pneumoniae isolates. Although moderate activity (54–83%) was observed against most potential AmpC-producing Enterobacterales isolates, ceftolozane/tazobactam exhibited poor in vitro (44.7–47.4%) activity against phenotypic AmpC Enterobacter cloacae isolates. Additionally, 251 (22.3%) P. aeruginosa isolates exhibited the carbapenem-NS phenotype, and their MDR and XDR rate was 63.3% and 33.5%, respectively. Fifteen (75%) of twenty Burkholderia cenocepacia complex isolates were inhibited by ceftolozane/tazobactam at MICs of ≤4 μg/mL. Conclusions With the increase in antibiotic resistance in Taiwan, it is imperative to periodically monitor the susceptibility profiles of clinically important GNB.

Introduction The rapid identification and detection of carbapenemase-producing Klebsiella pneumoniae (CPKP) isolates is crucial to ascertain outbreaks, as well as to limit their spread. The current reference method for this purpose is multilocus sequence typing (MLST), which is laborious and expensive. Consequently, alternative typing methods are gaining attention, such as Matrix-Assisted Laser Desorption Ionization–Time Of Flight Mass Spectrometry (MALDI-TOF MS). Methods This study sought to analyze MALDI-TOF MS as a typing method using 44 CPKP isolates that were well characterized by MLST. The most common types of samples from which these pathogens were isolated were skin and soft tissues (32%) and urine (29%). Half of the CPKP isolates were from hospitalized patients. Two approaches were followed for the analysis of the mass peak data obtained by MALDI-TOF MS. The first using all peaks obtained and the second using a selection of 21 characteristic peaks. Results The selection of 21 characteristic peaks showed greater discrimination power for ST11 and ST101. Principal component analysis (PCA) indicated that this dataset could be efficiently grouped with lineal classifiers. A Support Vector Machine (SVM) was chosen for this purpose after checking its capacity to classify bacterial strains on the basis of MALDI-TOF MS information. Conclusion SVM was able to discriminate between ST11 and ST101 with high accuracy. In conclusion, our results reveal MALDI-TOF MS as a promising alternative technique for typing of CPKP isolates.

Introduction Carbapenems are frequently used in the treatment of multidrug-resistant infections caused by Klebsiella pneumoniae. The aim of the study is to definition and incidence of transferable carbapenemase genes of carbapenem resistant K. pneumoniae (CRKP) and to determine clonal relatedness of these strains in tertiary care hospital in Turkey. Methods Identification of all 100 K. pneumoniae isolates and low sensitivity to any of the carbapenem group antibiotics were determined by Vitek-2 (BioMerieux, France). The frequency of carbapenemase genes (blaOXA-48, blaNDM, blaKPC, blaVIM, blaIMP) and extended spectrum beta-lactamase (ESBL) genes (blaCTX-M, blaSHV, blaTEM) which frequently detected in Turkey, have been investigated by multiplex polymerase chain reaction (PCR). Clonal relatedness was determined using Pulsed-field gel electrophoresis(PFGE). Results Ninety five isolates carried at least one of the carbapenemase genes (81.05% blaOXA-48, 38.9% blaNDM, 9.47% blaKPC,1.05% blaVIM). One isolate was carried the blaOXA-48+KPC and the two isolates were carried the blaKPC+NDM. PFGE demonstrated the presence of 24 pulse types and 63.09% of the isolates were in four main pulse types. Conclusions This study demonstrated the incidence of blaNDM is beginning to reach endemic levels, in addition to blaOXA-48 found endemic in Turkey. To our knowledge, this is the first report of the co-production of these two genes (blaKPC + NDM and blaOXA-48 + KPC) in CRKP isolates.

Background The emergence of carbapenemase-producing Enterobacteriaceae (CPE) represents a major clinical problem. Recently, the occurrence of CPE has increased globally, but epidemiological patterns vary across region. We report the trends in the genotypic distribution and antimicrobial susceptibility of CPE isolated from rectal and clinical samples during a four-year period. Methods Between January 2016 and December 2019, 1,254 nonduplicated CPE isolates were obtained from four university hospitals in Korea. Carbapenemase genotypes were determined by multiplex real-time PCR. Antimicrobial susceptibility was profiled using the Vitek 2 system (bioMerieux, Hazelwood, MO, USA) or MicroScan Walkaway-96 system (Siemens West Sacramento, CA, USA). The proportions of carbapenemase genotypes and nonsusceptibility were analyzed using Pearson's chi-square test. Results Among the 1,254 CPE isolates, 486 (38.8%), 371 (29.6%), 357 (28.5%), 8 (0.6%), 8 (0.6%), and 24 (1.9%) were Klebsiella pneumoniae carbapenemase (KPC), oxacillinase (OXA)-48-like, New Delhi metallo-β-lactamase (NDM), imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), and multiple producers, respectively. The predominant species was K. pneumoniae (72.6%), followed by Escherichia coli (6.5%). More than 90% of the isolates harboring KPC, NDM, and OXA-48-like were nonsusceptible to cephalosporins, aztreonam, and carbapenems. Conclusions The impact of CPE is primarily due to KPC-, NDM-, and OXA-48-like-producing K. pneumoniae isolates. Isolates carrying these carbapenemase are mostly multidrug-resistant. Control strategies based on these genotypic distributions and antimicrobial susceptibilities of CPE isolates are required.

Background Prevalence of extended-spectrum beta-lactamase-producing-Enterobacteriaceae (ESBL-E) has risen in patients with urinary tract infections. The objective of this study was to determine explore the risk factors of ESBL-E infection in hospitalized patients and establish a predictive model. Methods This retrospective study included all patients with an Enterobacteriaceae-positive urine sample at the first affiliated hospital of Jinan university from January 2018 to December 2019. Antimicrobial susceptibility patterns of ESBL-E were analyzed, and multivariate analysis of related factors was performed. From these, a nomogram was established to predict the possibility of ESBL-E infection. Simultaneously, susceptibility testing of a broad array of carbapenem antibiotics was performed on ESBL-E cultures to explore possible alternative treatment options. Results Of the total 874 patients with urinary tract infections (UTIs), 272 (31.1%) were ESBL-E positive. In the predictive analysis, five variables were identified as independent risk factors for ESBL-E infection: male gender (OR = 1.607, 95% CI 1.066–2.416), older age (OR = 4.100, 95% CI 1.678–12.343), a hospital stay in preceding 3 months (OR = 1.872, 95% CI 1.141–3.067), invasive urological procedure (OR = 1.810, 95% CI 1.197–2.729), and antibiotic use within the previous 3 months (OR = 1.833, 95% CI 1.055–3.188). In multivariate analysis, the data set was divided into a training set of 611 patients and a validation set of 263 patients The model developed to predict ESBL-E infection was effective, with the AuROC of 0.650 (95% CI 0.577–0.725). Among the antibiotics tested, several showed very high effectiveness against ESBL-E: amikacin (85.7%), carbapenems (83.8%), tigecycline (97.1%) and polymyxin (98.2%). Conclusions The nomogram is useful for estimating a UTI patient’s likelihood of infection with ESBL-E. It could improve clinical decision making and enable more efficient empirical treatment. Empirical treatment may be informed by the results of the antibiotic susceptibility testing.

Objectives: The incidence of healthy individuals carrying multidrug resistant Enterobacteriaceae, including extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-E), especially extended-...

Background Aggressive antimicrobial infections together with an increasing in resistance to antimicrobial medications cause a threat to immunocompromised individual. In this context, spiro compounds play an important role in drug discovery research due to their diverse biological activities including antimicrobial activity which is well documented in literature, because of their unique structural properties allow for easy interaction with the target enzyme of the biological system. This biological precedent encouraged us to design and synthesis of novel dispirooxindolopyrrolidine hybrid heterocycles via multicomponent cycloaddition protocol. Materials and methods Novel class of dispirooxindolopyrrolidine hybrid heterocycles has been synthesized by multicomponent 1,3-dipolar cycloaddition methodology and the structure of the products was determined through spectroscopic analysis. The synthesized organic compounds were evaluated for their antimicrobial activities using sensitivity test with standard agar well diffusion method. Results The synthesized new class of dispiropyrrolidine embedded indandione hybrids showed significant antimicrobial activity against carbapenemase producing Klebsiella pneumoniae (CKPs) isolated from hospital patients. Compound that possessing chlorine substituted on the aryl ring exhibited more potent antimicrobial activities and the zone of inhibitions was observed between 7.00 ± 0.09 and 18.40 ± 0.70 mm. The MIC value of compound 4b was 0.030 mg/mL against tested CKP. Conclusion A new class of dispiropyrrolidine heterocyclic hybrids were synthesized in good to excellent yield employing multicomponent 1,3-dipolar cycloaddition strategy. Among them, compounds bearing 4-chloro substituted on the aryl ring exhibited notable activity just equal to the standard drug, ciprofloxacin. Future studies are needed to elucidate the pharmacological properties of new compounds that were synthesized in our laboratory for the novel therapeutic development.

Summary Background Although sink- and drain-related carbapenemase-producing Enterobacterales transmission has been reported previously, there is limited research regarding the transmission of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales. Aim To investigate nosocomial ESBL-producing Klebsiella pneumoniae transmission via patient sinks and drains on a general surgical hospital ward. Methods ESBL-producing K. pneumoniae transmission on a surgical ward at Tokyo Medical University Hospital (built in July 2019) from July 2019 to February 2020 was investigated. Information regarding the relatedness of the isolates from the patients and the environment was provided by whole-genome sequence analysis. Findings Four clinical isolates of K. pneumoniae (TUM19831, TUM19832, TUM19833 and TUM19834) were detected during the study. TUM19831 was identified prior to moving to the new building and was detected again in the new building. TUM19832 and TUM19833 were detected in July 2019, and TUM19834 was detected in December 2019. TUM19835 and TUM19836 were detected in two different sinks and drains in July 2019, while a further two sinks and drains tested positive for TUM19837 and TUM19838 in February 2020. Whole-genome analysis revealed that all strains were ST307 and CTXM15 sequence types, and the isolates were indistinguishable by genetic analysis. Due to inadequate removal of the slime biofilm coating, the sinks needed to be cleaned again before TUM19837 and TUM19838 could be detected. Conclusions This study demonstrated the transmission of indistinguishable ESBL-producing K. pneumoniae strains from sinks and drains in the patient area of a general surgical hospital ward. There is a need to recognize this risk and develop optimal management strategies for plumbing systems in hospitals and other healthcare settings.

BackgroundKlebsiella pneumoniae is a World Health Organization high-priority antibiotic-resistant pathogen. However, little is known about Klebsiella lineages circulating in Nigeria.MethodsWe performed whole-genome sequencing (WGS) of 141 Klebsiella isolated between 2016 and 2018 from clinical specimens at 3 antimicrobial-resistance (AMR) sentinel surveillance tertiary hospitals in southwestern Nigeria. We conducted in silico multilocus sequence typing; AMR gene, virulence gene, plasmid, and K and O loci profiling; as well as phylogenetic analyses, using publicly available tools and Nextflow pipelines.ResultsPhylogenetic analysis revealed that the majority of the 134 K. pneumoniae and 5 K. quasipneumoniae isolates from Nigeria characterized are closely related to globally disseminated multidrug-resistant clones. Of the 39 K. pneumoniae sequence types (STs) identified, the most common were ST307 (15%), ST5241 (12%), ST15 (~9%), and ST25 (~6%). ST5241, 1 of 10 novel STs detected, is a single locus variant of ST636 carrying dfrA14, tetD, qnrS, and oqxAB resistance genes. The extended-spectrum β-lactamase (ESBL) gene blaCTX_M-15 was seen in 72% of K. pneumoniae genomes, while 8% encoded a carbapenemase. No isolate carried a combination of carbapenemase-producing genes. Four likely outbreak clusters from 1 facility, within STs 17, 25, 307, and 5241, were ESBL but not carbapenemase-bearing clones.ConclusionsThis study uncovered known and novel K. pneumoniae lineages circulating in 3 hospitals in Southwest Nigeria that include multidrug-resistant ESBL producers. Carbapenemase-producing isolates remain uncommon. WGS retrospectively identified outbreak clusters, pointing to the value of genomic approaches in AMR surveillance for improving infection prevention and control in Nigerian hospitals.

Objectives The objective of this study was to evaluate the efficacy of different dosing regimens of ceftazidime/avibactam (CZA) in patients with Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) pulmonary infections. Methods A total of 70 KPC-Kp strains were isolated from sputum and bronchoalveolar lavage samples of patients with pulmonary infections in three hospitals in northern China from April 2015 to October 2015. Monte Carlo simulation (MCS) was performed using population pharmacokinetic parameters of CZA combined with the minimum inhibitory concentration (MIC) distributions gained from antimicrobial susceptibility testing to predict the efficacy of different dosing regimens. Various CZA dosing regimens were modelled using MCS. Results The in vitro study showed potent activity of CZA against KPC-Kp strains with MIC50/90 values of 1/2 mg/L, with a susceptibility rate of 95.7%. The values of cumulative fraction of response (CFR) for bactericidal (50%fT>5 × MIC) target were as follows: for patients with creatinine clearance (CLCr) >51 mL/min, the CFR was 96.01% for 2.5 g CZA every 12 h (q12h) and 97.14% for 2.5 g CZA every 8 h (q8h); and for patients with moderate renal impairment (CLCr >30 to ≤50 mL/min), the CFR was 95.75% for 1.25 g CZA q12h and 97.09% for 1.25 g CZA q8h. Conclusion This study indicated that the recommended dose of CZA can provide adequate pharmacodynamic exposure for treating KPC-Kp pneumonia.

Objectives Proper use of antibacterial agents is required to prevent the spread of drug-resistant bacteria. To support clinicians, laboratories need to rapidly determine bacterial drug susceptibility/resistance. We have established a method to distinguish extended-spectrum β-lactamase (ESBL)-producing clinical isolates by capturing structural changes in β-lactam antibiotics using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Methods Clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, classified into ESBL-producing strains and sensitive strains based on the presence or absence of a CTX-M-type gene, were used. Test bacteria were cultured aerobically in solid-phase wells of “Eiken” DPD-1 dry plates at 35°C for 15 or 30 min with antibiotics [cefotaxime (CTX), cefpodoxime (CPDX), or piperacillin (PIPC)]. Then, the culture supernatants were used for analysis with a MALDI Biotyper. Results Signals derived from non-hydrolyzed products of antibiotics were observed in all strains. In the case of ESBL-producing strains, signals derived from the hydrolysis products of antibiotics were observed. Since the ratio of signal intensity derived from hydrolysis products divided by the total signal intensity detected was more than 11% for CTX and more than 6% for CPDX and PIPC, all strains were determined to be ESBL-producing bacteria. Conclusion The short incubation time of 15 minutes suggests that this method can identify ESBL-producing strains much more rapidly than conventional methods.

Background Progressive decline of immune response in HIV patients makes them susceptible to frequent bacterial infections. High usage of antibiotics influences the emergence of multidrug-resistant bacteria and worsens the clinical outcomes. In this study, the occurrence of drug-resistant genes in Gram-negative bacterial isolates from HIV patients in South India was analyzed. Methods A total of 173 Gram-negative bacterial (GNB) isolates from HIV patients were screened for antibiotic susceptibility profile using the Kirby-Bauer diskdiffusion method. Positivity of drug-resistant genes was analyzed using polymerase chain reaction method. Results In this study, 72.8% of bacterial isolates were obtained from urine specimens, and Escherichia coli (47.4%) was the predominantly isolated bacterium. Overall, 87.3% and 83.2% of GNB were resistant to 3rd generation cephalosporin antibiotics such as cefotaxime and ceftazidime, respectively, 56.6% were resistant to cephamycin (cefoxitin) and 43% to carbapenem (imipenem) antibiotics. Extended-spectrum β-lactamases (ESBL) production was noted among 79.5% of GNB isolates, followed by AmpC (57.1%) and Metallo β-lactamases (37.3%). Molecular analysis revealed that ESBL genes such as blaTEM (94.1%), blaCTX-M (89.2%), and blaSHV (24.2%) were detected at higher levels among GNB isolates. Carbapenemase-producing genes such as blaOXA-48 (20%), blaOXA-23 (2.6%), and both blaOXA-23 and blaOXA-51 like genes (2.6%) and AmpC producing genes such as blaCIT (26.7%), blaDHA (3.6%), and blaACC (1.8%) were detected at low-level. Conclusions This study concludes that ESBL producing genes are detected at high level among gram-negative bacterial isolates from HIV patients in South India.

This study was conducted to characterize the distribution of Salmonella isolates in a poultry processing facility and to identify their antibiotic resistance profiles. Salmonella enterica was detected in 146 samples (66.7%), and 125 isolates were identified as Salmonella Heidelberg (n = 123), Salmonella Abony (n = 1), and Salmonella O:4,5 (n = 1). Salmonella Heidelberg isolates were subjected to XbaI macrorestriction analysis and pulsed-field gel electrophoresis. The 66 pulsotypes obtained were grouped into four major clusters, indicating cross-contamination and persistence of this serotype in the processing facility. Selected S. enterica isolates were characterized by their antibiotic resistance, and most (n = 122, 97.6%) were multidrug resistant. Resistance to third-generation cephalosporins ceftazidime (84 isolates, 67.2%) and cefotaxime and ceftriaxone (91 isolates, 72.8%) was particularly prevalent. Production of extended-spectrum β-lactamases (ESBL) was identified in 24 isolates (19.2%), and ESBL-producing isolates were resistant to at least eight antibiotics. This study revealed the high prevalence of Salmonella Heidelberg in the poultry chain, providing insight into the ecology of this pathogen in this facility. The high prevalence of multidrug-resistant S. enterica is a concern due to the potential consequences for public health. HIGHLIGHTS

Background Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an emerging public health problem. This study explores the specifics of CRKP epidemiology in Colombia based on whole genome sequencing (WGS) of the National Reference Laboratory at Instituto Nacional de Salud (INS)’s 2013–2017 sample collection. Methods A total of 425 CRKP isolates from 21 departments were analyzed by HiSeq-X10®Illumina high-throughput sequencing. Bioinformatic analysis was performed, primarily using the pipelines developed collaboratively by the National Institute for Health Research Global Health Research Unit (GHRU) on Genomic Surveillance of Antimicrobial Resistance (AMR), and AGROSAVIA. Results Of the 425 CRKP isolates, 91.5% were carbapenemase-producing strains. The data support a recent expansion and the endemicity of CRKP in Colombia with the circulation of 7 high-risk clones, the most frequent being CG258 (48.39% of isolates). We identified genes encoding carbapenemases blaKPC-3, blaKPC-2, blaNDM-1, blaNDM-9, blaVIM-2, blaVIM-4, and blaVIM-24, and various mobile genetic elements (MGE). The virulence of CRKP isolates was low, but colibactin (clb3) was present in 25.2% of isolates, and a hypervirulent CRKP clone (CG380) was reported for the first time in Colombia. ST258, ST512, and ST4851 were characterized by low levels of diversity in the core genome (ANI > 99.9%). Conclusions The study outlines complex CRKP epidemiology in Colombia. CG258 expanded clonally and carries specific carbapenemases in specific MGEs, while the other high-risk clones (CG147, CG307, and CG152) present a more diverse complement of carbapenemases. The specifics of the Colombian situation stress the importance of WGS-based surveillance to monitor evolutionary trends of sequence types (STs), MGE, and resistance and virulence genes.

BackgroundKlebsiella pneumoniae is a critically important pathogen in the Philippines. Isolates are commonly resistant to at least two classes of antibiotics, yet mechanisms and spread of its resistance are not well studied.MethodsA retrospective sequencing survey was performed on carbapenem-, extended spectrum beta-lactam- and cephalosporin-resistant Klebsiella pneumoniae isolated at 20 antimicrobial resistance (AMR) surveillance sentinel sites from 2015-2017. We characterized 259 isolates using biochemical methods, antimicrobial susceptibility testing, and whole genome sequencing (WGS). Known AMR mechanisms were identified. Potential outbreaks were investigated by detecting clusters from epidemiologic, phenotypic and genome-derived data.ResultsPrevalent AMR mechanisms detected include blaCTX-M-15 (76.8%) and blaNDM-1 (37.5%). An epidemic IncFII(Yp) plasmid carrying blaNDM-1 was also detected in 46 isolates from 6 sentinel sites and 14 different sequence types (ST). This plasmid was also identified as the main vehicle of carbapenem resistance in 2 previously unrecognized local outbreaks of ST348 and ST283 at 2 different sentinel sites. A third local outbreak of ST397 was also identified but without the IncFII(Yp) plasmid. Isolates in each outbreak site showed identical STs, K- and O-loci, and similar resistance profiles and AMR genes. All outbreak isolates were collected from blood of children aged ConclusionWGS provided an in-depth understanding of the epidemiology of AMR in the Philippines, which was not possible with only phenotypic and epidemiologic data. The identification of three previously unrecognized Klebsiella outbreaks highlights the utility of WGS in outbreak detection, as well as its importance in public health and in implementing infection control programs.summaryWhole genome sequencing identified three distinct previously unrecognized local outbreaks in a retrospective study in the Philippines, along with an epidemic plasmid carrying antimicrobial resistance genes, highlighting its importance in antimicrobial resistance surveillance, outbreak detection and infection control.

ObjectivesComplicated urinary tract infections (cUTIs) are frequently encountered in hospitals and ICUs. Increasingly, the causative pathogens harbour enzymatic resistance mechanisms. Taniborbactam is a novel β-lactamase inhibitor with activity against Ambler class A, B, C and D β-lactamases. Herein, we assessed the efficacy of cefepime alone and the combination cefepime/taniborbactam in a neutropenic murine cUTI model.MethodsEighteen cefepime-resistant clinical isolates (9 Enterobacterales, 3 Pseudomonas aeruginosa and 6 Stenotrophomonas maltophilia; cefepime MIC = 32 to >512 mg/L) were assessed. Cefepime/taniborbactam MICs ranged from 0.06 to 128 mg/L. Human-simulated plasma regimens (HSRs) of cefepime alone and in combination with taniborbactam were developed in the murine cUTI model. The efficacy of cefepime HSR and cefepime/taniborbactam HSR was determined as the change in log10 cfu/kidney at 48 h compared with 48 h controls.ResultsMean ± SD initial bacterial burden was 5.66 ± 0.56 log10 cfu/kidney, which increased to 9.05 ± 0.39 log10 cfu/kidney at 48 h. The cefepime HSR was ineffective, as bacterial burden was similar to untreated controls (−0.14 ± 0.40 change in log10 cfu/kidney). In contrast, cefepime/taniborbactam exhibited substantial killing, with log10 cfu/kidney changes of −5.48 ± 1.3, −4.79 ± 0.3 and −5.04 ± 0.7 for ESBL/AmpC-, KPC- and OXA-48-harbouring Enterobacterales, respectively. Cefepime/taniborbactam also exhibited robust killing of P. aeruginosa (−6.5 ± 0.26) and S. maltophilia (−5.66 ± 0.71).ConclusionsHumanized exposures of cefepime/taniborbactam achieved robust killing of Enterobacterales, P. aeruginosa and S. maltophilia harbouring ESBL, AmpC, KPC and/or OXA-48. These data support the role of cefepime/taniborbactam for cUTI treatment for cefepime/taniborbactam MICs up to 32 mg/L.

Objectives To determine the transmission and molecular characteristics of blaNDM-producing Escherichia coli between companion animals and their healthcare providers at veterinary clinics in Guangzhou, China. Methods A total of 359 samples from companion animals and their healthcare providers were collected at 14 veterinary clinics in Guangzhou, China. Genomic characteristics and clonal relationships for blaNDM-positive E. coli and complete plasmid sequences were characterized based on WGS data from combined Illumina and MinION platform reads. Results Forty-five blaNDM-positive bacteria were recovered from companion animals (n = 43) and their healthcare providers (n = 2) at 10 veterinary clinics. Overall, E. coli (73.3%, 33/45) and Klebsiella pneumoniae (13.3%, 6/45) were the most prevalent species among the seven species of blaNDM-positive bacteria. Four blaNDM variants (blaNDM-1, blaNDM-4, blaNDM-5 and blaNDM-7) were identified in 45 blaNDM-positive bacteria and blaNDM-5 was the most prevalent (77.8%, 35/45). WGS indicated that the most prevalent STs were ST405 (8/33), ST453 (6/33), ST457 (6/33) and ST410 (5/33) among the 33 blaNDM-positive E. coli isolates. Phylogenomics and PFGE analysis revealed that clonal spread of blaNDM-positive ST453 E. coli isolates between companion animals and their healthcare providers was evident. In addition, two novel IncFIB plasmids carrying blaNDM-4 (pF765_FIB and pG908_FIB) were found in this study and indicated that IS26 may promote the horizontal transmission of blaNDM between different plasmid types. Conclusions In this study we conducted a large-scale investigation on the prevalence of blaNDM-positive E. coli isolates from companion animals and their healthcare providers and revealed the clonal spread of blaNDM-positive E. coli isolates between these two groups.

Summary New Delhi metallo-β-lactamase (NDM) gene confers high-level resistance to an array of β-lactams including carbapenems. Short- and long-read sequencing was used to investigate outbreaks of NDM-positive Enterobacterales including a potential horizontal gene transfer (HGT) event of an NDM-positive plasmid between Salmonella enterica and Klebsiella pneumoniae. Genomic analysis demonstrated a high degree of similarity between NDM-carrying plasmids from patient 1 in K. pneumoniae and patient 2 with S. enterica, K. pneumoniae and Klebsiella oxytoca, confirming an inter-species HGT event. The utility of whole-genome sequencing was demonstrated for in-hospital outbreaks, previously undetected using traditional infection-control surveillance.

In Gabon, few data exist on extended-spectrum beta-lactamases-producing Enterobacteriaceae (ESBL-PE). This study investigated ESBL-PE prevalence and the associated resistance genes in clinical samples (

Background Escherichia coli has appeared as an important opportunistic pathogen responsible for nosocomial infections in patients with immunodeficiency, particularly in leukemia patients. New Delhi metallo-beta-lactamase is an enzyme originally found in Enterobacteriaceae. Case presentation In this study, 80 isolates of Escherichia coli and Klebsiella pneumoniae were collected over the course of 2 years from two medical centers in Tehran, Iran. Production of carbapenemase was detected in the isolates using modified Hodge test. New Delhi metallo-beta-lactamase-1 genes were detected by polymerase chain reaction amplification with specific primers. Two New Delhi metallo-beta-lactamase-1-producing Escherichia coli strains were isolated from two Iranian patients with leukemia. These two patients were 6 and 15 years old, one female and the other male, from two oncology centers in Iran. The isolates were resistant to carbapenems (imipenem, meropenem), and two isolates were positive for carbapenemase production by modified Hodge test. Conclusions The emergence of New Delhi metallo-beta-lactamase-1-producing Escherichia coli is a threat for leukemia patients in oncology and hematology departments. We conclude that the incidence of multidrug resistant pathogens has increased among patients with leukemia and is life threatening.

The present study was conducted to detect the occurrence of beta-lactamase and biofilm-producing Escherchia coli and Salmonella in apparently healthy broiler birds reared in household and contract poultry farms. In total, 150 cloacal swabs were collected from apparently healthy broiler birds of various age groups reared in backyard (n = 100) and contract farms (n = 50) in West Bengal (India). The isolation rate of ESBL producers was significantly more (P < 0·05) reared in contract poultry farms than those reared in backyard. Majority of the E. coli isolates possessed blaCTX-M followed by blaSHV and blaTEM . Majority of the Salmonella strains possessed blaTEM followed by blaCTX-M , and no blaSHV was detected. The selected sequences of the PCR products were found cognate with blaCTX-M-1 , blaCTX-M-2 , blaCTX-M-9 , blaCTX-M-14 , blaCTX-M-15 , blaSHV-12 and blaTEM-52 . The study detected 46·8% of E. coli and 42·5% of Salmonella strains as biofilm producers. Beta-lactamase-producing Enterobacteriaceae strains showed resistance against tetracycline, chloramphenicol, doxycycline, co-trimoxazole and ampicillin and sensitivity to imipenem-EDTA, colistin and gentamicin. The study revealed the partial clonal relationship of ESBL sequences possessed by the poultry isolates of the present study and local clinical isolates available in the database. The study made consumer awareness about careful handling of live birds or poultry meat to avoid the zoonotic transmission of antimicrobial-resistant Enterobacteriaceae.

Introduction. The emergence of multiresistant enterobacteria producing extendedspectrum beta-lactamase (ESBL) in outpatients with urinary tract infections represents a public health problem in Perú. Objectives. To characterize multiresistant enterobacteria isolated from patients diagnosed with urinary tract infection in two Peruvian jungle departments using molecular techniques. Materials and methods. We conducted a descriptive, observational, and retrospective study of 61 urine culture isolates from two departments in the Peruvian jungle during 2017-2018. Resistance profiles were identified using the MicroScan™ automated system and a conventional polymerase chain reaction (PCR) was used for the detection of blaCTX-M, blaTEM and blaSHV genes. Results. The most common positive ESBL enterobacteria for each department were Escherichia coli in Madre de Dios (10/40; 25%) and Ucayali (16/21; 76.2%). Gene blaCTX-M was the most prevalent in both departments (25/61; 41%), followed by blaTEM (15/61; 24.6%), and blaSHV (10/61; 16.4%). As for the antimicrobial susceptibility profile, we detected resistance levels of 72.6% for ampicillin, 82.3% for cephalothin, and 88.7% for nitrofurantoin. Conclusions. BLEE-producing multi-resistant enterobacteria strains in both departments were 57.4% and blaCTX-M was the most common gene.Introducción. La aparición de enterobacterias multirresistentes y productoras de betalactamasas de espectro extendido (BLEE) en pacientes de consulta externa con infecciones urinarias, representa un problema de salud pública en Perú. Objetivos. Caracterizar molecularmente enterobacterias multirresistentes aisladas de pacientes con diagnóstico de infección urinaria y procedentes de dos departamentos de la selva peruana. Materiales y métodos. Se hizo un estudio descriptivo, observacional y retrospectivo de 61 aislamientos de urocultivo procedentes de la selva peruana durante 2017 y 2018. Los perfiles de resistencia se identificaron utilizando el sistema automatizado MicroScan™ y para la detección de los genes blaTEM, blaCTX-M, blaSHV se empleó una reacción en cadena de la polimerasa (PCR) convencional. Resultados. Las enterobacterias positivas para BLEE más frecuentes por departamento fueron Escherichia coli en Madre de Dios (25 %, 10/40) y Ucayali (76,2 %, 16/21). En ambos departamentos, el gen blaCTX-M fue el más frecuente (25/61; 41 %), seguido por blaTEM (15/61; 24,6 %) y blaSHV (10/61; 16,4 %). En el perfil de sensibilidad antimicrobiana, se detectó 72,6 % de resistencia contra ampicilina, 82,3 % contra cefalotina y 88,7 % contra nitrofurantoína. Conclusiones. El porcentaje de cepas de enterobacterias multirresistentes productoras de BLEE en ambos departamentos fue del 57,4 % y el gen bla CTX-M fue el más frecuente.

Objetive. The aim of this study was to analyze the activity of the imipenem-relebactam combination (IMI/REL) against a collection of multidrug-resist Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii clinical isolates. Material and methods. The study was conducted in two tertiary hospitals in Spain and included 192 clinical isolates of these 3 genera (139 resistant and 53 susceptible to IMI). The MICs for IMI with and without REL (at a fixed concentration of 4 mg/L) were determined by a standard broth microdilution method according to international recommendations. Results. All IMI-susceptible E. coli strains were also susceptible to IMI/REL. Enterobacterales resistant to IMI due to the production of carbapenemases, the MIC50 and MIC90 decreased from 64/256 with IMI to 8/64 mg/L with IMI/REL. This high activity was principally detected among isolates with KPC enzymes. Enterobacterales with class B carbapenemases, P. aeruginosa carrying VIM carbapenemase and A. baumannii strains showed no changes on IMI MIC50 or MIC90 after adding REL. Among P. aeruginosa strains without carbapenemase the MIC for IMI/REL was reduced between 1 to 5 dilutions. Conclusions. IMI/REL showed high activity against the strains that carry Klebsiella pneumoniae carbapenemase (KPC) and against carbapenem-resistant P. aeruginosa unrelated to the VIM enzyme, mainly AmpC beta lactamase associated with impermeability. Against strains carrying oxacillinase 48 (OXA-48) associated with extended-spectrum beta-lactamase (ESBL), IMI/REL presented activity only slightly better than IMI and had no beneficial effect superior to IMI against A. baumannii.

Multidrug resistance due to the production of extended-spectrum beta-lactamases (ESBLs) is a major problem in human as well as in veterinary medicine. These strains appear in animal and human microbiomes and can be the source of infection both in animal and in human healthcare, in accordance with the One Health theorem. In this study we examined the prevalence of ESBL-producing bacteria in food-producing animals. We collected 100 porcine and 114 poultry samples to examine the prevalence of ESBL producers. Isolates were identified using the MALDI-TOF system and their antibiotic susceptibility was tested using the disk diffusion method. ESBL gene families and phylogroups were detected by polymerase chain reactions. The prevalence of ESBL producers was relatively high in both sample groups: 72 (72.0%) porcine and 39 (34.2%) poultry isolates were ESBL producers. Escherichia coli isolates were chosen for further investigations. The most common ESBL gene was CTX-M-1 (79.3%). Most of the isolates belong to the commensal E. coli phylogroups. The porcine isolates could be divided into three phylogroups, while the distribution of the poultry isolates was more varied. In summary, ESBL-producing bacteria are prevalent in the faecal samples of the examined food-producing animals, with a dominance of the CTX-M-1 group enzymes and commensal E. coli phylogroups.

Purpose To study distribution of carbapenemase genes namely; New Delhi metallo-beta-lactamase (blaNDM), Oxacillinase-48 (blaOXA48), Verona Integron-Encoded Metallo-beta-lactamase (blaVIM) and Imipenemase (blaIMP) in carbapenem resistant Enterobacterales (CRE), isolated from clinical samples. Method This cross-sectional study was conducted at a tertiary care hospital of western Maharashtra over six months period. CREs were identified by conventional disc diffusion and modified carbapenem inactivation method (mCIM). A total of 50 consecutive CRE isolates from clinical samples were subjected to home brewed polymerase chain reaction (PCR) for detection of carbapenemases. Results Out of the 50 CRE isolates, at least one of the four carbapenemase genes was detected in 49 (98%) isolates. The frequency of distribution of these genes were NDM 90% (n = 45), OXA48 60% (n = 30) and VIM 12% (n = 6). Dual combination of blaNDM and blaOXA48 (50%) was the commonest pattern observed, which was frequently associated with Klebsiella pneumoniae. Conclusions The study indicate high prevalence of NDM warranting strict anti-microbial stewardship practices. Surveillance of CRE and resistance mechanism is essential to monitor the trend and take informed decision for appropriate anti-microbial therapy.

Concomitant prevention of SARS-CoV-2 and extensively drug-resistant bacteria transmission is a difficult challenge in intensive care units dedicated to COVID-19 patients. We report a nosocomial cluster of four patients carrying NDM-1 plasmid-encoded carbapenemase-producing Enterobacter cloacae. Two main factors may have contributed to cross-transmission: misuse of gloves and absence of change of personal protective equipment, in the context of COVID-19-associated shortage. This work highlights the importance of maintaining infection control measures to prevent CPE cross-transmission despite the difficult context and that this type of outbreak can potentially involve several species of Enterobacterales. Supplementary Information The online version contains supplementary material available at 10.1186/s13756-021-01022-6.

Purpuse The carbapenem-resistant Bacteroides fragilis group (CR-BFG) bacteria have been reported in several countries recently with increasing global attention. The high incidence of CR-BFG isolated from our hospitalized patients has become an important problem. Therefore, we aimed to determine the frequency and associated factors for intestinal colonization by carbapenem-non-susceptible BFG (CNS-BFG) among adult patients hospitalized at intensive care units, neurosurgery and internal medicine wards in our hospital. Methods Rectal swabs (n = 1200), collected from 766 patients between February 2014 and March 2015, were inoculated onto kanamycin-vancomycin-leaked blood agar containing 0.125 mg/L meropenem. The isolates were identified by MALDI-TOF MS. Susceptibility testing was performed by agar dilution method. The carbapenemase gene (cfiA) was detected by PCR. Logistic regression analysis was used to evaluate the associated factors for intestinal colonization by CNS-BFG. Results A total 180 non-duplicate BFG isolates were obtained from 164 patients. Ten different species, including Parabacteroides distasonis (n = 46, 25.6%), and Bacteroides fragilis (n = 30; 16.6%), were identified. Twenty-five percent of the isolates were non-susceptible to meropenem (MIC >2 mg/L). The highest prevalence of meropenem resistant strains (MIC >8 mg/L) was detected among B. fragilis (n = 12), followed by Parabacteroides spp. (n = 4). All but one B. fragilis strains were cfiA gene positive. Hospital admission, increasing Charlson score, use of antibiotics; including carbapenems in past three months, colonization with other accompanying carbapenem-resistant Gram negative bacteria (Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa), and having undergone surgical operations were significantly associated with RCS- BFG colonization. Conclusions The high carriage rate of CNS-BFG in hospitalized patients may lead to worse clinical outcomes, such as serious infections and mortality, and deserves attention.

Wastewater is considered a hotspot niche of multi-drug and pathogenic bacteria such as Enterobacteriaceae-producing extended-spectrum beta-lactamases (ESBL-E). Thus, the aim of this meta-analysis was to evaluate the prevalence of ESBL-E in different wastewater sources. Different databases (Medline, EMBASE, and Cochrane Library) were searched from inception to March 2021. Data were analyzed using random-effects modeling, and subgroup and meta-regression analyses were used to ascertain heterogeneity among the subgroups. Fifty-seven observational studies were selected, and the pooled prevalence of ESBL-E in wastewater was 24.81% (95% CI, 19.28–30.77). Escherichia coli had the highest ESBL prevalence. The blaCTX-M genes were the most prevalent in the selected studies (66.56%). The pooled prevalence of ESBL was significantly higher in reports from America (39.91%, 95% CI, 21.82–59.51) and reports studying hospital and untreated wastewaters (33.98%, 95% CI, 23.82–44.91 and 27.36%, 95% CI, 19.12–36.42). Overall, this meta-analysis showed that the prevalence of ESBL-E in wastewater is increasing over time and that hospital wastewater is the most important repository of ESBL-E. Therefore, there is a need for developing new sewage treatment systems that decrease the introduction of resistant bacteria and antibiotic residues. HIGHLIGHTS The global prevalence of Enterobacteriaceae-producing extended-spectrum beta-lactamases (ESBL-E) in wastewater was found to be 24.81%.; The pooled prevalence of ESBL-E was significantly higher in reports studying hospital wastewater.; The highest prevalence of ESBL-E was in America, and the lowest prevalence was in Europe.; Among ESBL genes, blaCTX-M genes had the highest prevalence, followed by blaTEM and blaSHV.

Objectives To compare the in vitro activity of plazomicin and two older aminoglycosides (gentamicin and amikacin) against 180 isolates of Escherichia coli and Klebsiella pneumoniae, including subsets of 60 non-ESBL-producing, 60 ESBL-producing and 60 carbapenem-resistant (46 carrying blaOXA-48, 11 carrying blaNDM and 3 carrying blaOXA-48 and blaNDM) strains. Methods MICs of plazomicin, gentamicin and amikacin were determined by a gradient diffusion method. Gentamicin and amikacin MICs were interpreted according to CLSI criteria and EUCAST breakpoint tables. Plazomicin MICs were interpreted using FDA-defined breakpoints. Results All non-ESBL-producing and ESBL-producing isolates were susceptible to plazomicin. The plazomicin susceptibility rate (71.7%) in carbapenem-resistant isolates was significantly higher than those observed for gentamicin (45%) and amikacin (56.7% and 51.7% according to CLSI and EUCAST breakpoints, respectively). Gentamicin, amikacin and plazomicin susceptibility rates (35.6% for gentamicin; 44.4% and 37.8% for amikacin according to CLSI and EUCAST breakpoints, respectively; 64.4% for plazomicin) in carbapenem-resistant K. pneumoniae were significantly lower than those observed for carbapenem-resistant E. coli isolates (73.3% for gentamicin; 93.3% for amikacin and plazomicin). Gentamicin, amikacin and plazomicin susceptibility rates for blaNDM-positive isolates were lower than those observed for blaOXA-48-positive isolates, but differences were not statistically significant. Among the isolates that were non-susceptible to both gentamicin and amikacin, the plazomicin susceptibility rate was less than 30%. Conclusions Although plazomicin showed excellent in vitro activity against carbapenem-susceptible isolates, the plazomicin resistance rate increased to 35.6% among carbapenem-resistant K. pneumoniae and further increased to 45.5% among blaNDM-positive isolates.

Background In China, OXA-48-producing Enterobacterales have been identified sporadically, causing only small-scale outbreaks in certain regions. This study aimed to investigate the molecular epidemiology, transmission and evolution of OXA-48-producing Enterobacterales and pOXA-48 from mainland of China.Enterobacterales METHODS: We conducted a multi-center bacterial resistance monitoring project from 2013 to 2018. The genome sequencing of OXA-48-produicng isolates was performed. Single-nucleotide polymorphism (SNP) was analysed. Eleven isolates were selected for subsequent single-molecule real-time (SMRT) sequencing. Genome sequences were annotated, and alignment of the complete sequences of the blaOXA-48-carrying plasmids from a subset of isolates that underwent long read sequencing was performed. Results A total of 41 OXA-48-producing Enterobacterales were involved in this study, including 34 K. pneumoniae, 3 E. coli, 3 E. cloacae and one K. oxytoca. OXA-48-produicng K. pneumoniae (OXAKp) ST383, ST147 and ST11 caused outbreaks of different scales in our hospital. In addition, OXA-48-producing E. coli ST156 and ST648, E. cloacae ST414 and ST418, and K. oxytoca ST34 were also identified. The blaOXA-48 gene was embedded in a Tn1999.2 structure, which was located in IncL plasmids with different sizes (63.58∼109.14 kb). Importantly, K. pneumoniae ST11 co-producing KPC-2 and OXA-48 has been identified in our hospital and it was possible that KPC-2-producing K. pneumoniae ST11 obtained the blaOXA-48-carrying plasmid during the spread. A novel blaOXA-48-carrying IncL plasmid with size of 109 kb has been identified from OXAKp ST11. It was possible that two plasmids in OXAKp ST383 were integrated to form this larger plasmid. Conclusions The OXA-48-produicng Enterobacterales were sporadic in China. Importantly, K. pneumoniae ST11 co-producing KPC-2 and OXA-48 has emerged and caused outbreak in China. This high-risk multidrug-resistant clone exhibited high compatibility and strong integration ability with foreign resistant plasmids.

Objectives We sequenced two IncA/C plasmids harbouring blaCTX-M-2 in Klebsiella pneumoniae clinical isolates and compared their antibiotic resistance islands. Methods Transconjugants were obtained from two clinical K. pneumoniae isolates harbouring blaCTX-M-2. Plasmid DNA from transconjugants underwent short-read whole-genome sequencing, reads were assembled, and gaps were closed by PCR and sequencing. Determination of plasmid replicons, antibiotic resistance genes, identification and characterisation of insertion sequence (IS) elements, and comparison with publicly available plasmid sequences were performed. Results blaCTX-M-2 was located in a complex class 1 integron In35::ISCR1::blaCTX-M-2, inserted in two different transposons designated Tn7057 and Tn7058, that reside in the resistance islands of plasmids pUR-KP0923 and pUR-KP1025, respectively. The general modules of both transposons were In35::ISCR1::blaCTX-M-2–Tn1000-like–Tn2*–ISKpn11-12-13 variable module–ΔTn21. In Tn7057 there was ΔIS10R–catA2 associated with an additional ISKpn13. Both plasmids belonged to IncC type 2 and ST3. pUR-KP0923 was 167 138 bp in length and had a 37 926-bp resistance island at position 4 (RI-4). Plasmid pUR-KP1025 was 168 128 bp with a RI-4 of 36 222 bp. Conclusion This report describes the molecular nature of two transposons (Tn7057 and Tn7058) harbouring blaCTX-M-2 that reside in IncC type 2 ST3 plasmids. These transposons mediate resistance to oxyimino-cephalosporins, gentamicin and, in the case of Tn7057, chloramphenicol. CTX-M-2 is an important extended-spectrum β-lactamase (ESBL) to South American epidemiology. It is remarkable that despite being only two plasmid sequences, the information revealed here could contribute to a better understanding of the resistance islands from IncC type 2 plasmids.

Objectives This study aims to infer phylogenetic relationship of OXA-232-producing Klebsiella pneumoniae (OXA232Kp) strains collected from a Chinese hospital, and to determine the composition and genetic background of antimicrobial resistance genes (ARGs) among these strains. Methods A total of three non-duplicated OXA232Kp strains were collected from a Chinese hospital. Whole genome sequencing (WGS) was used to determined their genome sequences, and then a genomic comparison of ARG-carrying genetic elements from these three strains with related sequences were performed. Phylogenetic analysis was conducted by constructing maximum-likelihood phylogenetic tree. Results Compared with other Chinese sequence type 15 (ST15)-OXA232Kp strains, three ST15-OXA232Kp strains in this study could be divided into a single subgroup in phylogenetic relationship. The composition and genetic background of ARGs were identical in these three strains. A total of three ARG-carrying genetic elements or multidrug resistance (MDR) regions were determined, including a truncated Tn2013-like IS-based transposition unit, a unit transposition Tn6867b and a 40.9-kb MDR region. Conclusions This study reported a clonal dissemination of ST15-OXA232Kp strains carrying multiple ARGs in a Chinese hospital. A comprehensive evolutionary and genomic analysis gained a deeper understanding of OXA232Kp. Further surveillance and study should be advocated to prevent the dissemination of OXA232Kp strains in China.

To assess the in vitro activity of cefiderocol (CFDC) against a collection of both ceftazidime-avibactam (CZA) susceptible and resistant KPC-producing Enterobacterales (KPC-EB) isolates. Secondly, to assess its synergistic activity in combination with different antibiotics. One hundred KPC-EB isolates were tested: 60 CZA susceptible and 40 CZA resistant. Among them, 17 pairs of CZA susceptible and resistant KPC-producing Klebsiella pneumoniae (KPC-Kp) isolates were collected from 17 distinct patients before and after CZA treatment, respectively. CFDC susceptibility was evaluated by both broth microdilution (lyophilized panels; Sensititre; Thermo Fisher) and disk diffusion testing. Results were interpreted using EUCAST breakpoints. Synergistic activity of CFDC in combination with CZA, meropenem-vaborbactam, imipenem, and amikacin against six characterized KPC-Kp strains, before and after acquisition of CZA resistance, was evaluated using gradient diffusion strip crossing method. CFDC resistance rate was significantly higher in CZA resistant EB subset than in the susceptible one (p

Background The combination aztreonam/avibactam is currently under Phase 3 trials for the treatment of serious infections caused by Gram-negative bacteria including those with MBLs. Objectives To investigate the resistance mechanisms in Enterobacterales exhibiting aztreonam/avibactam MICs of ≥4 mg/L. Methods Among 8787 Enterobacterales, 17 (0.2%) isolates exhibited an aztreonam/avibactam MIC of ≥4 mg/L. Isolates were sequenced and screened for β-lactamases. Sequences of porins, penicillin-binding protein 3 (PBP3) and expression levels of AmpC and AcrA were evaluated. Results Eleven (11/4154 isolates; 0.26%) Escherichia coli, three (3/1981; 0.15%) Klebsiella pneumoniae and three (3/628; 0.5%) Enterobacter cloacae were identified. All E. coli showed either an ‘YRIK’ or ‘YRIN’ insertion in PBP3. In general, these isolates carried blaCMY and/or blaCTX-M variants, except for one isolate from Korea that also produced NDM-5 and one isolate from Turkey that produced OXA-48. Two DHA-1-producing K. pneumoniae overexpressed acrA and had a premature stop codon in either OmpK35 or OmpK36, whereas a third K. pneumoniae carried blaPER-2 and had a premature stop codon in OmpK35. All three E. cloacae expressed AmpC at levels ≥570-fold, but sequence analysis did not reveal known amino acid alterations associated with decreased avibactam binding or increased hydrolysis of β-lactams. Minor amino acid polymorphisms within OmpC, OmpF and PBP3 were noted among the E. cloacae. Conclusions A small number of isolates (0.2%) met the inclusion criteria. E. coli showed altered PBP3 as the most relevant resistance mechanism, whereas K. pneumoniae had multiple resistance mechanisms. Further investigations are needed to clarify resistance in E. cloacae.

New Delhi Metallo-β-lactamase-1 (NDM-1) offers carbapenem antibiotics resistance that creates an evolving challenge in treating bacterial infections. NDM-1-bearing strains were observed in surface waters around New Delhi in 2010 and after then identified globally. The usage of antibiotics may hasten the growth of the NDM-1-producing bacteria, which pose severe hazards to human and animal health. The emergence of the NDM-1 in the aquatic environment is turning out to be a growing concern worldwide. NDM-1 gene conferring resistance to a widespread class of antibiotics has been observed in bacteria disseminated in animal production wastewaters, hospital sewage, domestic sewage, industrial effluents, wastewater treatment plants, drinking water, surface water, and even in groundwater. This review recapitulates the currently published research studies on the prevalence and geographical distribution of the NDM-1 gene in the aquatic environment, its habitats, and healthcare risk associated with NDM-1-producing bacteria, in addition to molecular techniques employed to reveal the occurrence of the NDM-1 in the aquatic environment, including conventional polymerase chain reaction, real-time qPCR, DNA hybridization, and microarray-based methods.

Background: T2DM patients are more likely to have UTIs caused by resistant organisms such as ESBLs producing bacteria. Challenging reliable identification and prompt characterization of in-vitro susceptibilities of these bacteria are the first steps of deciding the appropriate antimicrobial therapy for UTIs caused by them. Objectives: To isolate and identify E. coli and K. pneumoniae from urine of T2DM patients with UTIs, to determine antibiotic resistance pattern among isolates, and to identify ESBLs production phenotypically and genotypically. Material and method: All samples were cultured on Cystine-Lactose-Electrolyte-Deficient Agar medium (CLED) by using calibrated loop. Growth of 100 colonies or more, i.e. 105 colony forming units (CFU)/mL urine was considered as signifi- cant bacteriuria. Isolation and identification were done according to standard method. All isolates were tested for antibiotic susceptibility testing by the disc diffusion method according to CLSI guidelines. Phenotypic detection of ESBLs was done by double-disk synergy test. Genotypic detection of blaTEM, blaSHV and blaCTX-M genes by using PCR. Results: Results of this study showed that E. coli and K. pneumoniae were the dominant bacterial isolates, they constituted 103 (91.2%) out of 113 urine isolates. E. coli (58. 4%) K. pneumoniae (32.7%), Enterococcus spp. (4.4%), Proteus spp. (2.7%) and Pseu- domonas spp. (1.8%). About 25 (24.3%) out of 103 E. coli and K. pneumoniae isolates were ESBLs positive by DDST, and 22 (88.0%) out of them had ESBLs encoding genes by conventional PCR. The most common gene detected was blaTEM (59.1%), followed by blaSHV (27.3%). CTX-M had not been detected in any of testes isolates. Conclusion: blaTEM and blaSHV genes were detected in 22 out of 25 ESBLs producing E. coli and K. pneumoniae isolates phenotypically detected by DDST. blaTEM was found to be the predominant gene (59.1%), while blaCTX-Mene was not detected in any of tested isolates. Keywords: Extended Spectrum β-Lactamases; Type 2 diabetes mellitus; Urinary tract infections; Phenotypic; genotypic methods.

Background: Escherichia coli and Klebsiella pneumoniae are commonly implicated in urinary tract infections accounting for majority of the antimicrobial resistance encountered in hospitals. Objectives: To determine the prevalence and antimicrobial susceptibility of extended-spectrum beta-lactamases (ESBLs) producing E. coli and K. pneumoniae among patients in Anyigba, Nigeria. Methods: This hospital-based cross-sectional study was conducted using urine samples from 200 patients of Grimmard Catholic hospital and Maria Goretti hospital. Urine samples were processed to identify ESBL-producing E. coli and K. pneu- moniae using standard microbiological techniques. Isolates were then tested against antimicrobial agents. Results: A total of 156 bacterial isolates were recovered consisting 128 of E. coli and 28 of K. pneumoniae. Extended spec- trum beta-lactamases production was observed in 69% of E. coli and 31% of K. pneumoniae. These pathogens were resistant to 3 or more antibiotics. Of the antimicrobials tested, cefotaxime demonstrated the highest rates of resistance (100%) for both ESBL-producing E. coli and K. pneumoniae. Fifty-four isolates of ESBL-producing E. coli showed a high level of resist- ance to amoxicillin clavulanic acid (83.3%), ciprofloxacin (83.3%), and ceftazidime (79.6%). ESBL-positive K. pneumoniae iso- lates were highly resistant to ciprofloxacin (75%), and amoxicillin clavulanic acid (83.3%). Cefoxitin (62.5%) and gentamicin (66.7%) showed substantially higher rates of resistance against these isolates while all 24 strains were resistant to imipenem. Conclusion: This study indicated the prevalence of ESBL-positive Gram-negative pathogens in these study sites and also demonstrated their resistance to a few antibiotics. This highlights the need for new antimicrobials that are potent and im- proved policy on use of antibiotics. Keywords: Antibiotic resistance; ESBLs; Escherichia coli; Klebsiella pneumoniae; Anyigba.

Background: The noteworthy spread of carbapenem-resistant K. pneumoniae (CR-KP) isolates represents a significant safety threat. Objective: Determination of the carbapenemase genes incidence among CR-KP clinical isolates in Kafrelsheikh, Egypt. Methods: A total of 230 K. pneumoniae isolates were recovered from four hospitals in Kafrelsheikh, Egypt. Susceptibility testing was conducted using Kirby-Bauer method and automated-Vitek2 system. CR-KP isolates were tested using modified Hodge test (MHT) and combined disk synergy test. PCR and DNA sequencing were conducted for CR-KP isolates to rec- ognize the included carbapenemase-genes. Results: Out of 230 K. pneumoniae isolates, 50 isolates presented resistance to carbapenem (meropenem). All 50 CR-KP iso- lates were multidrug-resistant (MDR). Genes like blaNDM-1 and blaOXA-48 were the only detected genes among CR-KP with an incidence of 70.0% and 52.0%, respectively. Up to 74.0% of the tested isolates carried at least one of the two record- ed genes, among them 48.0% co-harbored both blaNDM-1 and blaOXA-48 genes. The accession-numbers of sequenced blaNDM-1 and blaOXA-48 genes were MG594615 and MG594616, respectively. Conclusion: This study reported a high incidence of MDR profile with the emergence of blaNDM-1 and blaOXA-48 genes co-existence in CR-KP isolates in Kafrelsheikh, Egypt. Hence, more restrictions should be applied against the spread of such serious pathogens. Keywords: Klebsiella pneumoniae; Egypt; carbapenem resistance; MDR; PCR; blaNDM-1; blaOXA-48; sequencing.

Introduction The aim of this study was to monitor the development of drug-resistant bacteria isolated from acute uncomplicated cystitis (AUC) and to evaluate methodology of the survey conducted by collecting only clinical data. Methods We enrolled female patients at least 16 years of age diagnosed with AUC in 2018. Patient information including age, menopausal status, and results of bacteriological examination were collected and analyzed regardless of bacterial identification, antimicrobial susceptibility testing or extended-spectrum β-lactamase (ESBL) detection method. Results A total of 847 eligible cases were collected. Escherichia coli (E. coli) was the most frequently isolated bacterial species at about 70%, with proportions of fluoroquinolone-resistant E. coli (QREC) and ESBL-producing E. coli isolates at 15.6% and 9.5% of all E. coli isolates, respectively. The proportion of Staphylococcus saprophyticus (S. saprophyticus) was significantly higher in premenopausal women. Regarding the drug susceptibility of E. coli, isolates from Eastern Japan had significantly higher susceptibility to cefazolin, cefotiam and cefpodoxime and lower susceptibility to levofloxacin in postmenopausal women. ESBL-producing E. coli isolates had a high susceptibility to tazobactam-piperacillin, cefmetazole, carbapenems, aminoglycosides, and fosfomycin. In S. saprophyticus, the susceptibility to β-lactams including carbapenems was 40–60%. Conclusions The proportions of QREC and ESBL-producing E. coli were increasing trends and lower susceptibility to LVFX in postmenopausal women was observed. Such surveillance, consisting of the collecting only clinical data, could be conducted easily and inexpensively. It is expected to be continuously performed as an alternative survey to conventional one collecting bacterial strains.

Objectives Community onset urinary tract infections (COUTIs) drew attention recently owing to their increased prevalence and associations with resistant pathogens. The study is aimed at investigating the etiology of COUTIs as well as prevalence and the related risk factors of extended-spectrum β-lactamase (ESBL) in COUTIs in China. Methods The prospective study was performed in nineteen hospitals during November 1, 2017 and August 31, 2019. Non-duplicated isolates from COUTIs were included. The ESBL phenotypic confirmation test was performed and whole genomes were sequenced for all the ESBL-positive bacteria for further analysis. The risk factors for ESBL-producing bacterial infections were analyzed using binary logistic regression. Results A total of 1760 COUTI cases were included in this study. Escherichia coli (1332, 75.7%), Klebsiella pneumoniae (110, 6.3%) and Enterococcus faecalis (52, 3.0%) were the top three common pathogens of COUTIs in China. The overall positive rate of ESBLs in Enterobacterales was 37.2% (562/1512). The age (OR=1.007, P = 0.041), solid malignant tumor (OR=1.668, P = 0.016), prostate diseases (OR=2.035, P = 0.010), history of lithotripsy for urinary calculi (OR=2.009, P = 0.030), history of urological surgery (OR=1.869, P = 0.009) and cephalosporin use within 3 months (OR=1.503, P = 0.025) were independent risk factors for ESBL-producing organisms causing COUTIs. The predominant ESBL types were CTX-Ms, among which CTX-M-14, CTX-M-55 and CTX-M-27 were the most common subtypes. ST131 and ST1193 were the predominant sequence types of ESBL-producing E. coli (ESBL-EC). Most of the tested antimicrobial agents showed significantly higher non-susceptible rates in the ESBL positive group as compared with ESBL-negative group (P Conclusions Enterobacterales, especially E. coli, is the most common pathogen in COUTIs in China and ESBL-producers are highly prevalent. Thus, early prediction depending on risk factors seems to be crucial to determine the appropriate empirical therapy for infections caused by ESBL-producing pathogens.

Proteus mirabilis is abundant in soil and water. Although this bacterium is part of the normal human intestinal flora, it can cause serious infections in humans, including complicated urinary tract infections. This pathogen is also commonly associated with multidrug resistance. In the present study, analysis of 1,093 samples from foods of animal origin and animal intestinal samples recovered 232 P. mirabilis isolates identified by PCR assay. Of these 232 isolates, 72 produced β-lactamase (determined by both phenotypic and genotypic methods), with the highest prevalence in poultry cloacal swabs (11.82%) followed by mutton (9.18%), khoa (6.32%), pork (5.63%), pig rectal swabs (5.52%), beef (5.45%), and chicken (5.13%) but none from sheep rectal swabs and bovine rectal swabs. Among β-lactamase genes, blaTEM was the predominant gene detected (59 isolates) followed by blaOXA (11 isolates), blaSHV (5 isolates), blaFOX (5 isolates), blaCIT (4 isolates), blaCTX-M1 and blaCTX-M9 (2 isolates each) and blaCTX-M2, blaDHA, and blaEBC (1 isolate each). None of the isolates carried blaACC, blaMOX, or carbapenemase genes (blaVIM, blaIMP, blaKPC, and blaNDM-1). Dendrogram analysis of enterobacterial repetitive intergenic consensus sequences and repetitive extragenic palindromic sequences obtained with PCR analysis of β-lactamase-producing isolates revealed 63 isolates, but 9 isolates did not yield bands. The analysis revealed that 6.58% of the samples had β-lactamase-producing P. mirabilis isolates that may affect food safety and contaminate the environment. Further genotyping revealed the genetic relationships between isolates of different origin. These findings emphasize the need for careful use of antibiotics to control the spread of β-lactamase-producing bacteria. HIGHLIGHTS

Carbapenems, although originally introduced against multidrug-resistant (MDR) Gram negative bacilli (GNB), are now advocated for initial empiric use resulting in increasing carbapenem-resistant (CR) GNB. In this study, we analyzed the frequencies of CR-GNB and compared their resistance patterns against other antibiotics. Overall, 42% (1,014/2,420) of CR-GNB were isolated (range: 29-59%), with similar frequencies among hospitalized and community-acquired infections. However, the CR frequencies in Acinetobacter baumannii were significantly higher in the hospitalized patients (>50%). In addition, the CR-GNB isolates showed significantly higher resistance to the other antibiotics-fluoroquinolones, aminoglycosides, sulfonamides, and ureidopenicillins compared to carbapenem-sensitive isolates, thereby limiting further treatment options. Majority of CR-GNB isolates were extended spectrum β-lactamase producers (38-72%) and MDR (19-61%). Pan-drug resistant (PDR) frequencies among these MDR isolates ranged from 21% (Proteus spp.) to 100% (A. baumannii). Overall, CR-GNB are predominantly MDR or PDR and so warrant continuous antibiotic surveillance to provide better management of the infectious diseases.

BACKGROUND: This study aimed to investigate the distribution pattern of carbapenemases and evaluate their solitary contribution to carbapenem resistance. METHODS: One hundred and twelve isolates of Acinetobacter baumannii (A. baumannii) isolated from the intensive care unit (ICU) of a southern China tertiary hospital were identified, and antimicrobial susceptibility tests (ASTs) of these strains were determined. Common carbapenemases were detected and the distribution pattern of carbapenemases was analyzed. Logistic regression and general linear model analyzed were performed to identify the correlation between antimicrobial susceptibility and carbapenemase genes. RESULTS: These 112 strains were classified into a carbapenem-resistant A. baumannii (CRAB) group (71.7%) and a carbapenem-susceptible A. baumannii (CSAB) group (28.3%). Carbapenemase genes, including blaOXA-51-like (100.0%), blaOXA-23 (93.4%), ISAba1/blaOXA-51-like (27.5%), blaNDM-1 (8.8%), blaOXA-24 (2.2%) and blaOXA-58 (2.2%) were detected in CRAB strains, and no blaSIM, blaVIM and blaIMP gene in these 112 isolates. There was a statistically significant difference between CSAB and CRAB group in carrying blaOXA-23 (P

Background: In the past few centuries, a widespread increase in antimicrobial resistance has been observed among Klebsiella species. The antibiotic- resistant strains of the genus Klebsiella are becoming a serious threat in clinical settings due to their involvement in severe invasive and non-invasive infections. The emergence of resistance among these strains is associated with their strong enzymatic activity against several broad-spectrum antibiotics. These enzymes include beta-lactamases, extended-spectrum beta-lactamases (ESBL), AmpC beta-lactamases, and carbapenemases. These resistance enzymes are capable of hydrolyzing various broad-spectrum drugs like extended-spectrum cephalosporin and carbapenems. Objective: The present study was conducted to determine the emerging resistance among Klebsiella strains by identifying the production of carbapenemase enzyme phenotypically and the frequency of the NDM resistance gene by a polymerase chain reaction. Methods: In this study, 236 Gram-negative isolates from different clinical laboratories were identified. Out of which, 125 isolates were found as Klebsiella species by using standard microbiological techniques. Minimum inhibitory concentrations (MIC) were determined using eight representative antibiotics by the Macro broth dilution method. Phenotypic detection of carbapenemase producing Klebsiella species was performed by Modified Hodge Test. Phenotypic findings were then checked and compared with genotypic results obtained by using the Polymerase chain reaction (PCR) for the detection of resistance genes responsible for the production of carbapenemase. Results: In this study, carbapenemase production was found only in 6 (5%) Klebsiella isolates by using the phenotypic method; however, 3 isolates out of 125 were screened positive for the gene NDM-1. Conclusion: Since we are considering carbapenems as the last therapeutic option for treating infections, mainly caused by Gram-negative isolates, the prevailing resistance against this drug is widely disseminating. It is better to evaluate the antibiotic susceptibility, phenotypic screening as well genotypic screening (where possible) for implementing strict antibiotic control policies in health care settings, hospitals, laboratories, etc.

Aims Klebsiella pneumoniae has been reported to develop increased antibiotic resistance. Ceftazidime-avibactam (CZA) is a novel antibiotic with activity against serine-lactamase. Here, we investigated the sensitivity of carbapenem-resistant K. pneumoniae (CRKP) to CZA and the mechanisms of drug resistance in our hospital. Methods and results Patient characteristics were obtained from medical records. K. pneumoniae and its antibiotic susceptibility were determined using the Vitek-2 Compact instrument. The antibiotic resistance genes KPC, NDM, OXA-48, VIM, IMP, CIM, SPM, TMB, SMB, SIM, AIM and DIM were detected using real-time PCR. Multilocus sequence typing was used for genetic RELATEDNESS analysis. In total, 121 CRKP strains were isolated from patients in the intensive care unit (51·2%), senior ward (12·4%) and neurosurgery department (10%). With an average age of 72·5 years, most patients were in care for respiratory (34·7%), brain (20·7%), digestive tract (13·2%) and cardiovascular (8·3%) diseases. Specimens were predominantly obtained from sputum (39·67%), urine (29·75%) and blood (6·61%). Conclusion Of 23 CZA-resistant CRKP strains (19·01%), ST11 being the most common at 56·52%, 11 NDM-1-positive (47·83%) and four NDM-5-positive (17·39%) strains were detected. Significance and impact of the study Our study indicates that CZA resistance occurs in ~19·01% CRKP strains and that blaNDM-1 and blaNDM-5 might be critical for resistance.

Objectives Bacteria that acquire plasmids incur a biological cost. Despite this fact, clinical Enterobacteriaceae isolates commonly contain multiple co-existing plasmids harbouring carbapenemase genes. Methods Six different plasmids carrying blaNDM-1, blaNDM-5, blaCTX-M-15, blaKPC-2, blaOXA-181 and blaOXA-232 genes were obtained from Klebsiella pneumoniae and Escherichia coli clinical isolates. Using the E. coli DH5α strain as recipient, 14 transconjugants with diverse plasmid combinations (single or double plasmids) were generated. For each of these, the effects of plasmid carriage on the bacterial host were investigated using in vitro and in vivo competition assays; additionally, the effects were investigated in the context of biofilm formation, serum resistance and survival inside macrophages. Transcriptomic changes in single- and double-plasmid recipients were also investigated. Results Increased in vitro and in vivo competitiveness was observed when two plasmids carrying blaNDM-1 and blaOXA-232 were co-introduced into the host bacteria. However, DH5α::pNDM5 + pOXA232 and other double-plasmid recipients did not show such competitiveness. DH5α::pNDM5 + pOXA181 did not show any fitness cost compared with a plasmid-free host and single-plasmid transconjugants, while both the double-plasmid recipients with pCTXM15 or pKPC2 exhibited a fitness burden. The double-plasmid recipient DH5α::pNDM1 + pOXA232 also exhibited increased biofilm formation, serum resistance and survival inside macrophages. Transcriptomic analysis revealed that the genes of DH5α::pNDM1 + pOXA232 involved in metabolic pathways, transport and stress response were up-regulated, while those involved in translation were down-regulated. Conclusions Our study suggests that bacterial strains can gain fitness through the acquisition of multiple plasmids harbouring antibiotic resistance genes, which may be mediated by transcriptomic changes in the chromosomal genes of the bacterial host.

Extended-spectrum β-lactamases’ (ESBLs) production is the main resistance mechanism to third-generation cephalosporins (TGCs) in gram-negative bacilli. In Argentina, there is a high prevalence of cefotaximase-type ESBLs (CTX-M). For this reason, dissociated resistance phenotype (DRP) displaying a profile of resistance to cefotaxime (CTX) and susceptibility to ceftazidime (CAZ) might be detected. The aims of this study were to determine the prevalence of DRP in Enterobacterales clinical isolates, to characterize the mechanisms responsible for this phenotype and to evaluate the in vitro behaviour against different antibiotics. Sixty Enterobacterales resistant to any TGC were studied, and among them, 25% displayed a DRP. The β-lactamases associated with DRP were 5/11 CTX-M-2, 4/11 CTX-M-14, 1/11 CTX-M-15 and 1/11 CMY-2 in E. coli, 2/3 CTX-M-2 and 1/3 CMY-2 in P. mirabilis and 1/1 CTX-M-14 in K. pneumoniae. Furthermore, CTX-M-2 and CTX-M-14 were related with DRP in both wild-type isolates and the corresponding transconjugants. Time-kill experiments showed CAZ bactericidal activity on CTX-M-2-and CTX-M-14-producing strains and bacterial regrowth in those CMY-2 producers. An opposite behaviour was evident when cefepime (FEP) was used. However, CAZ and gentamicin combination showed a synergistic effect against the CMY-2 producers. We concluded that Enterobacterales with DRP responded differently to CAZ or FEP depending on the type of β-lactamase they possess, suggesting that these cephalosporins could be a therapeutic option. Therefore, the characterization of the involved resistance mechanism might contribute to define the appropriate antibiotic treatment.

Background Klebsiella pneumoniae is predominantly exists in the pus of the human wounds and it creates massive infections in the skin and causes serious health associated infections. Modern antibiotics are highly active in the treatment of wound infections. In this study was aimed to determine resistance of K. pneumoniae screened from wound specimens of patients. Sample was collected from the pus of the patients associated with secondary infection. Methods Samples were serially diluted and the isolated bacterial strains were characterized by biochemical tests, colony morphology and Gram’s staining methods. Resistance of K. pneumoniae was tested using antibiotics such as, Gentamycin, Ampicillin, Tetracycline, Cefurooxime, Oxacillin, Ofloxacin, Erythromycin, Nalidic acid, Cefepine, Piperacillin, Norfloxacin, Imipenem, Nitrofurantoin, Amikacin, Ciprofloxacin, Vancomycin, Meropeneum and Cefotaxime with Kirby-Bauer disc diffusion method. Results Among the 73 K. pneumoniae strains, four strains produced AmpC and ESBLs, 42 strains produced ESBLs and 7 bacterial strains synthesized only AmpC enzyme. Four stains produced ESBLs and showed multidrug resistance against various antibiotics. Most of the strains synthesized extracellular polysaccharides and mediated biofilm formation. Among the K. pneumoniae strains, K. pneumoniae PS02 showed multidrug resistant against most of the tested antibiotics. It produced ESBLs and AmpC enzyme. To produce secondary metabolites, actinomycetes were isolated and characterized as Streptomyces sp. AC14. The secondary metabolite was effective against Klebsiella strains. Conclusions To conclude, secondary metabolites extracted from Streptomyces sp. AC14 was found to be effective against multidrug resistant bacterium. Further studies are warranted to analyze the drug hydrolyzing pathways of bacteria and to identify the mechanism of action of secondary metabolites from Streptomyces sp. AC14.

Antibiotic-resistant infections caused by extended-spectrum β-lactamases (ESBLs) and carbapenemases are increasing worldwide. Bacteria resistant to extended-spectrum cephalosporins and last resort carbapenems have been reported from food animals and their environments. Other concentrated nonfood-producing animals such as mink farming can be a reservoir of bacteria resistant to these critically important antibiotics. The objective of this study was to determine the prevalence of ESBL-producing bacteria and carbapenem-resistant (CR) bacteria from mink fecal (

Worapong Nasomsong,1 Parnrada Nulsopapon,2,3 Dhitiwat Changpradub,1 Manat Pongchaidecha,2 Supanun Pungcharoenkijkul,4 Piraporn Juntanawiwat,5 Waristha Simsiriporn,5 Wichai Santimaleeworagun2,3 1Division of Infectious Diseases, Department of Internal Medicine, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand; 2Department of Pharmacy, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand; 3Pharmaceutical Initiative for Resistant Bacteria and Infectious Diseases Working Group [PIRBIG], Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand; 4Pharmacy Unit, Nopparat Rajathanee Hospital, Bangkok, Thailand; 5Division of Microbiology, Department of Clinical Pathology, Phramongkutklao Hospital, Bangkok, ThailandCorrespondence: Wichai SantimaleeworagunDepartment of Pharmacy, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, 73000, ThailandTel +6634 255 800Fax +6634 255 801Email swichai1234@gmail.comPurpose: MBL and OXA-48 genes in carbapenem-resistant Enterobacterales (CRE) have emerged as a major public health problem worldwide, including Thailand. Due to the lack of susceptibility data and dosing regimens of ceftazidime-avibactam (CZA) against CRE in Thailand, especially in colistin-resistant era, we aimed to demonstrate in vitro susceptibility data of CZA and optimal dose based on Monte Carlo simulation of CZA to expand the treatment options.Patients and Methods: We collected 49 carbapenem-resistant Klebsiella pneumoniae (CRKP) clinical isolates from unique patients at Phramongkutklao Hospital (June–October 2020). CZA disk diffusion and E-test testing were performed to obtain minimum inhibitory concentration (MIC). Each drug regimen was simulated using the Monte Carlo technique to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR).Results: The most common genotypes of CRKP were blaOXA-48 (53.1%) and blaOXA-48 +blaNDM (42.8%). CZA showed 47.7% and 90.5% susceptible rate against all genotypes of carbapenemases and OXA-48 type CRKP isolates. The MIC50 and MIC90 of CZA against CRKP were 2 and > 256 μg/mL. The categorical agreement (CA) between disk diffusion and E-test testing of CZA against CRKP was 95.4%. The CZA dosing regimens of 2.5 g infused 2– 3 h every 8 h achieved ≥ 90% of the target of free ceftazidime plasma concentration over MIC (%fTime >MIC) ≥ 50% and 100% against isolates MICs of ≤ 8 and ≤ 8 μg/mL, respectively. The avibactam regimens also provided 100%fTime at 0.5 μg/mL. Based on CFR ≥ 90%, no CZA regimens were effective against all of the studied CRKP isolates except CRKP carrying OXA-48.Conclusion: CZA exhibited a fairly susceptible rate among the OXA-48-positive isolates in Thailand. The current suggested dose of CZA with prolonged infusion appears appropriate to achieve the pharmacokinetic/pharmacodynamic targets of ceftazidime and avibactam against CRKP carrying blaOXA-48.Keywords: CRE, metallo-beta-lactamase, Monte Carlo, oxacillinase