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Abstract Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections are a major public health problem, requiring the use of last-resort antibiotics such as colistin. However, there is concern regarding the emergence of isolates resistant to this agent. The report describes two patients with urinary tract infection (UTI) and ventilator-associated pneumonia (VAP) infection caused by CRKP strains. The first case was a 23-year-old male with UTI caused by a strain of ST16 co-harboring bla CTX-M, bla TEM, bla SHV, bla NDM, bla OXA-48-like genes. The second case was a 39-year-old woman with VAP due to hypervirulent ST337-K2 co-harboring bla SHV, bla NDM, bla OXA-48-like, iucA, rmpA2 and rmpA . The patients’ general condition improved after combination therapy with colistin (plus meropenem and rifampin, respectively) and both of them recovered and were discharged from the hospital. This study highlights the necessary prevention and control steps to prevent the further spread of CRKP strains should be a priority in our hospital.

BackgroundHelicobacter pylori infection is a primary global health concern. However, the widespread use of antibiotics, particularly macrolides such as clarithromycin, has increased resistance among H. pylori strains. This study aimed to investigate the prevalence of macrolide resistance in H. pylori in different world regions.MethodsThis systematic literature search was performed using the appropriate search syntax after searching PubMed, Embase, Web of Science, and Scopus databases between May 2015 and December 2023. Statistical analysis was performed using Pooled and random effects model in R and the metafor package.ResultsA total of 7,768 articles were retrieved. After a thorough evaluation, 155 studies (by 178 reports) were finally eligible for inclusion in this systematic review and meta-analysis. According to the results, the majority of studies (178 reports from 43 countries) assessed clarithromycin susceptibility, with a pooled prevalence of 33.3% and high heterogeneity between studies (I2 = 98.57%, p

BackgroundHelicobacter pylori, a bacterium associated with severe gastrointestinal diseases and malignancies, poses a significant challenge because of its increasing antibiotic resistance rates. This study aimed to identify potential drug targets and inhibitors against H. pylori using a structure-based virtual screening (SBVS) approach.MethodsCore-proteome analysis of 132 H. pylori genomes was performed using the EDGAR database. Essential genes were identified and human and gut microbiota homolog proteins were excluded. The DAH7PS protein involved in the shikimate pathway was selected for the structure-based virtual screening (SBVS) approach. The tertiary structure of the protein was predicted through homology modeling (based on PDB ID: 5UXM). Molecular docking was performed to identify potential inhibitors of DAH7PS among StreptomeDB compounds using the AutoDock Vina tool. Molecular dynamics (MD) simulations assessed the stability of DAH7PS-ligand complexes. The complexes were further evaluated in terms of their binding affinity, Lipinski’s Rule of Five, and ADMET properties.ResultsA total of 54 novel drug targets with desirable properties were identified. DAH7PS was selected for further investigation, and virtual screening of StreptomeDB compounds yielded 36 high-affinity binding of the ligands. Two small molecules, 6,8-Dihydroxyisocoumarin-3-carboxylic acid and Epicatechin, also showed favorable RO5 and ADMET properties. MD simulations confirmed the stability and reliability of DAH7PS-ligand complexes, indicating their potential as inhibitors.ConclusionThis study identified 54 novel drug targets against H. pylori. The DAH7PS protein as a promising drug target was evaluated using a computer-aided drug design. 6,8-Dihydroxyisocoumarin-3-carboxylic acid and Epicatechin demonstrated desirable properties and stable interactions, highlighting their potential to inhibit DAH7PS as an essential protein. Undoubtedly, more experimental validations are needed to advance these findings into practical therapies for treating drug-resistant H. pylori.

ABSTRACT Rapid detection of carbapenemase-producing Enterobacteriaceae (CPE) is urgently needed to prevent their spread in healthcare settings. Here, we have evaluated the performance of the phenotypic methods for detection of carbapenemase production directly from bacterial cultures. A total of 99 clinical and rectal Enterobacteriaceae isolates were included (81 carrying known carbapenemase-encoding genes and 18 without carbapenemase production). All isolates were subjected to the five phenotypic tests including in-house Carba NP (iCarba NP), modified-Carba NP, E-Test MBL, modified Hodge test (MHT), and commercial combination disk test. Test results were read at different time points for iCarba NP and modified-Carba (1 min, 5 min, 15 min, 1 h and 2 h). The sensitivity and specificity of the iCarba NP were 78.87% and 100%, respectively, whereas those of the modified-Carba NP test were 95.06% and 94.44%, respectively. False-negative results were detected in four OXA-48 isolates with the use of modified-Carba NP, whereas one non-carbapenemase isolate had false-positive results. The sensitivity/specificity was 91.30%/100% and 80.25%/83.33% for the E-Test MBL and MHT, respectively. The sensitivity and specificity of the aminophenylboronic acid synergy test were 100% and 97.94%, respectively, whereas those of the dipicolinic acid synergy test were 82.61% and 96.23%, respectively. Rapid, simple, and reliable methods are needed for laboratory detection of CPE isolates to improve the detection and surveillance of these clinically relevant pathogens in an epidemiological context. We conclude that the modified-Carba NP test can be one of the reliable tests for the prediction of carbapenemase-producing bacteria.IMPORTANCEThe emergence of carbapenem resistance among Gram-negative bacteria is a serious global health threat. Here, we investigate the performance of the five phenotypic assays against carbapenemase-producing and carbapenemase-non-producing Enterobacteriaceae. Accurate and rapid detection of CPE isolates is critically required for clinical management and treatment of infections caused by these organisms. Among the five evaluated phenotypic tests, the mCNP test presented the highest sensitivity (95.06%) and, therefore, can be considered the best test to be used as a screening phenotypic methodology.

BackgroundEnterococcus faecium is one of the members of ESKAPE pathogens. Due to its resistance to antimicrobial agents, treating this bacterium has become challenging. The development of innovative approaches to combat antibiotic resistance is necessary. Phage therapy has emerged as a promising method for curing antibiotic-resistant bacteria.MethodsIn this study, E. faecium phages were isolated from wastewater. Phage properties were characterized through in vitro assays (e.g. morphological studies, and physicochemical properties). In addition, whole genome sequencing was performed. A hydrogel-based encapsulated phage was obtained and its structure characteristics were evaluated. Wound healing activity of the hydrogel-based phage was assessed in a wound mice model.ResultsThe purified phage showed remarkable properties including broad host range, tolerance to high temperature and pH and biofilm degradation feature as a stable and reliable therapeutic agent. Whole genome sequencing revealed that the genome of the EF-M80 phage had a length of 40,434 bp and harbored 65 open reading frames (ORFs) with a GC content of 34.9% (GenBank accession number is OR767211). Hydrogel-based encapsulated phage represented an optimized structure. Phage-loaded hydrogel-treated mice showed that the counting of neutrophils, fibroblasts, blood vessels, hair follicles and percentage of collagen growth were in favor of the wound healing process in the mice model.ConclusionThese findings collectively suggest the promising capability of this phage-based therapeutic strategy for the treatment of infections associated with the antibiotic-resistant E. faecium. In the near future, we hope to expect the presence of bacteriophages in the list of antibacterial compounds used in the clinical settings.

Abstract Background Colistin and carbapenem-resistant Klebsiella pneumoniae (Col-CRKP) represent a significant and constantly growing threat to global public health. We report here an outbreak of Col-CRKP infections during the fifth wave of COVID-19 pandemic. Methods The outbreak occurred in an intensive care unit with 22 beds at a teaching university hospital, Isfahan, Iran. We collected eight Col-CRKP strains from seven patients and characterized these strains for their antimicrobial susceptibility, determination of hypermucoviscous phenotype, capsular serotyping, molecular detection of virulence and resistance genes. Clonal relatedness of the isolates was performed using MLST. Results The COVID-19 patients were aged 24–75 years with at least 50% pulmonary involvement and were admitted to the intensive care unit. They all had superinfection caused by Col-CRKP, and poor responses to antibiotic treatment and died. With the exception of one isolate that belonged to the ST11, all seven representative Col-CRKP strains belonged to the ST16. Of these eight isolates, one ST16 isolate carried the iucA and ybtS genes was identified as serotype K20 hypervirulent Col-CRKP. The bla SHV and bla NDM-1 genes were the most prevalent resistance genes, followed by bla OXA-48 and bla CTX-M-15 and bla TEM genes. Mobilized colistin-resistance genes were not detected in the isolates. Conclusions The continual emergence of ST16 Col-CRKP strains is a major threat to public health worldwide due to multidrug-resistant and highly transmissible characteristics. It seems that the potential dissemination of these clones highlights the importance of appropriate monitoring and strict infection control measures to prevent the spread of resistant bacteria in hospitals.

Abstract Background and Objective The emergence and widespread dissemination of antibiotic resistance in A. baumannii, has become a globally challenge. The increasing hospital outbreaks by multi-drug resistant (MDR) A. baumannii strains, shows the necessity of continuous monitoring to find sources of resistant strains in hospitals. This study aimed to identify the presence of class 1 integrons and metallo-β-lactamase (MBL) related genes in A. baumannii isolates from hospital environment. Methods In order to identify A. baumannii isolates, a total of 297 environmental samples were collected from burn wards and intensive care units (ICUs) of two university hospitals. Resistance to common antibiotics was studied by disk diffusion method and microbroth dilution assay was used to determine the minimum inhibitory concentrations (MICs) of imipenem, colistin and tigecycline. The A. baumannii isolates were studied by polymerase chain reaction (PCR) for the presence of class 1 integrons (intI1, intl CS) and metallo-β-lactamases (MBLs) (bla IMP, bla VIM, bla NDM) genes. Results A. baumannii was identified in 68/297 (22.9%) of hospital environment. All A. baumannii strains were multidrug-resistant (MDR), but none of them were resistant to colistin, tigecycline and ampicillin-sulbactam. All (100%) and 38 (95.0%) of A. baumannii isolates from ICUs and burn wards were imipenem resistant respectively. Class 1 integrons was identified in 30/40 (75.0%) and 23/28 (82.1%) isolates from burn wards and ICUs respectively. Two different types of gene cassettes were identified, which included: arr-2, ereC, aadA1, cmlA5 and arr2, cmlA5. MBL genes including bla VIM and bla IMP were detected in 26/28 (92.8%), 27/28(96.4%) and 39/40 (97.5%) and 31/40 (77.5%) of the isolates from the ICUs and the burn wards respectively. None of the isolates contained the bla NDM−1 gene. Conclusion The findings of the present study showed that the isolation rate of MBL producing carbapenem-resistant A. baumannii (CRAB) was relatively high in the environmental surface of burn wards and ICUs, which can be considered as a potential source of outbreaks in hospitalized patients.

Abstract Background Certain clonal complexes (CCs) of Klebsiella pneumoniae such as CC147 (ST147 and ST392) are major drivers of bla NDM dissemination across the world. ST147 has repeatedly reported from our geographical region, but its population dynamics and evolutionary trajectories need to be further studied. Methods Comparative genomic analysis of 51 carbapenem-nonsusceptible strains as well as three hypervirulent K. pneumoniae (hvKp) recovered during 16-months of surveillance was performed using various bioinformatics tools. We investigated the genetic proximity of our ST147 strains with publicly available corresponding genomes deposited globally and from neighbor countries in our geographic region. Results While IncL/M plasmid harboring bla OXA-48 was distributed among divergent clones, bla NDM-1 was circulated by twenty of the 25 CC147 dominant clone and were mostly recovered from the ICU. The NDM-1 core structure was bracketed by a single isoform of mobile genetic elements (MGEs) [ΔISKpn26-NDM-TnAs3-ΔIS3000-Tn5403] and was located on Col440I plasmid in 68.7% of ST392. However, various arrangements of MGEs including MITESen1/MITESen1 composite transposon or combination of MITESen1/ISSen4/IS903B/IS5/ISEhe3 on IncFIb (pB171) were identified in ST147. It seems that ST392 circulated bla NDM-1 in 2018 before being gradually replaced by ST147 from the middle to the end of sample collection in 2019. ST147 strains possessed the highest number of resistance markers and showed high genetic similarity with four public genomes that harbored bla NDM-1 on the same replicon type. Mainly, there was a convergence between clusters and isolated neighboring countries in the minimum-spanning tree. A conserved arrangement of resistance markers/MGEs was linked to methyltransferase armA which was embedded in class 1 integron in 8 isolates of ST147/ST48 high-risk clones. Conclusion Our findings highlight the dynamic nature of bla NDM-1 transmission among K. pneumoniae in Iran that occurs both clonally and horizontally via various combinations of MGEs. This is the first analysis of Iranian ST147/NDM + clone in the global context.

BackgroundThe global spread of plasmids carrying carbapenemase genes within carbapenem resistant Acinetobacter baumannii (CRAB) strains poses a worldwide public health issue. In this study, we conducted a comprehensive genetic analysis of plasmids and chromosomes harboring the major carbapenemase genes (blaNDM, blaKPC, blaVIM, blaIMP, blaGES, blaOXA-58-like, blaOXA-24/40-like, blaOXA-143-like, and blaOXA-23-like) in CRAB strains using bioinformatic tools.MethodsWe retrieved plasmids and chromosomes carrying the major carbapenemase genes from GenBank. The size, replicon type, and conjugal apparatus of the plasmids were also determined. Furthermore, allele types, co-existence of other antimicrobial resistance genes alongside carbapenemases in plasmids or chromosomes, co-occurrence of carbapenemase genes, gene repetition, and sequence types (ST) of whole genomes were characterized.ResultsThe database contained 113 plasmids and 38 chromosomes harboring carbapenemase genes. This investigation revealed that blaNDM and blaOXA-58-like were the predominant allele types in both the plasmids and chromosomes. Nine (7.96%) plasmids with blaNDM-1 were potentially conjugative. The most common replicon types of the plasmids were R3-T1, R3-T8, R3-T2, R3-T23, and RP-T1. The analysis revealed that blaNDM-1 and blaOXA-58-like genes possessed the highest variety of co-existence with other antibiotic resistance genes. The co-occurrence of dual carbapenemases was identified in 12 plasmids and 19 chromosomes. Carbapenemase gene repetitions were identified in 10 plasmids and one chromosome. Circular alignment revealed that the plasmids carrying the co-occurrence of blaNDM-1 and blaOXA-58 were more homogeneous. However, there was heterogeneity in certain regions of these plasmids. According to the minimum spanning tree (MST) results, the majority of the plasmids belonged to the genomes of ST2Pas, ST1Pas, ST422Pas, ST622Pas, and ST85Pas.ConclusionA. baumannii appears to have a strong ability for genome plasticity to incorporate carbapenemase genes on its plasmids and chromosomes to develop resistance against carbapenems. Mobilizable plasmids harboring carbapenemases significantly contribute to the dissemination of these genes. The genetic structure of the plasmids revealed a strong associations of class I integrons, ISAba-like structures, Tn4401 elements, and aac (6′)-Ib with carbapenemases. Furthermore, gene repetition may also be associated with carbapenem heteroresistance.

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAB) is a global health crisis. This study aimed to determine the clonal relatedness of antibiotic-resistant A. baumannii isolates in hospitalized patients who suffered from burn wound infection. Methods One hundred and six A. baumannii isolates from 562 patients with burn wound infections, were identified and examined for antimicrobial susceptibility. Detection and characterization of carbapenem-hydrolyzing class D OXA-type beta-lactamases (CHDLs) were performed by PCR assays. The clonal relatedness of A. baumannii isolates was determined by multilocus sequence typing (MLST) according to the Pasteur scheme, dual-sequence typing of bla OXA−51-like and ampC genes, and RAPD-PCR method. Results All isolates were carbapenem-resistant while susceptible to colistin, minocycline, doxycycline, and ampicillin-sulbactam. The intrinsic bla OXA−51-like was detected in all isolates, and bla OXA−23-like was identified in 92.5% of isolates. However, bla OXA−143-like and bla OXA−58-like genes were not detected among isolates. Four distinct bla OXA−51-like alleles were determined as follows: bla OXA−317 (67.0%), bla OXA−90 (9.4%), bla OXA−69 (17.0%), and bla OXA−64 (6.6%) and four ampC (bla ADC) allele types including ampC-25 (6.6%), ampC-39 (9.4%), ampC-1 (17.0%), and bla ADC−88 (67.0%) were identified. MLST (Pasteur scheme) analysis revealed four ST types including ST136 (singleton), ST1 (CC1), ST25 (CC25), and ST78 (singleton) in 71, 18, 7, and 10 of A. baumannii strains, respectively. Five RAPD clusters including A (1.9%), B (26.4%), C (57.5%), D (7.5%), and E (1.9%) were characterized and 5 (4.7%) strains were found to be singletons. Conclusion The present study demonstrated that there was a high prevalence of bla OXA−23-like producing CRAB in the clinical setting. The majority of isolates belonged to ST136 (singleton). However, bla OXA−23-like producing multi-drug resistant international clones including ST1, and emerging lineages (e.g. ST25 and ST78) were also identified. Interestingly, in this study ST2 was not detected.

Abstract Background The hypervirulent pathotype of Klebsiella pneumoniae (hvKp) is mainly mediated by large virulent plasmids. It seems that these hypervirulent plasmids (HVPs) are accumulating antimicrobial resistance genes (ARGs) and are turning quickly into drug-resistant hypervirulent hybrids. Therefore, molecular mechanisms involved in this convergence needs to be investigated to control their global spread. Methods In this study, the complete sequence of 79 non-redundant hypervirulent plasmids were retrieved from GenBank and their genetic features, hypervirulence and antimicrobial resistance patterns (AMR) as well as their putative transmission capability were compared using bioinformatics tools. Results The majority of HVPs belonged to clonal complex (CC)23, and sequence type (ST)11. IncFIB and IncHI1B were the most prevalent plasmid replicon types. Out of 79 plasmids, 78 were positive for iutA and iucA. The iucC, iucB and iucD genes were found in 77 plasmids. Almost 26% of the HVPs were potentially conjugative of which 71% carried AGRs. ARGs against beta-lactams, carbapenems, quinolones, aminoglycosides, chloramphenicols, tetracyclines and macrolides were detected in 30% of HVPs. Class 1 integron and prophage structures harboring multiple ARGs were found in eight plasmids. Insertion sequences (IS)6, IS110 and IS1380 appeared to be important genetic elements in transmission of ARGs. Conclusions The high prevalence of iucA and iutA suggests their strong capability for rapid and accurate genetic markers for discrimination of hvKp in the laboratory. This study indicated the important role of mobile genetic elements (MGEs) in the emergence of drug-resistance in hypervirulent strains. The high prevalence of putative conjugative hybrids implies higher incidence of multidrug-resistant (MDR)-hvKp strains in near future.

ABSTRACT: Objectives: The Enterobacter cloacae complex (ECC) are causatives of hospital-acquired infections. The antimicrobial resistance (AMR) and virulence profiling of ECC promotes our knowledge for their elimination in clinical settings. Methods: We assembled the whole genome of four clinical carbapenem-resistant ECCs and characterized their AMR and virulence profiles using whole genome sequencing. Results: The chromosomes length scaled from minimum 3 949 952 bp (for P2) to maximum 4 976 575 bp (for P3). Strains P1 and P2 belonged to sequence type (ST)182. P3 and P4 belonged to ST477 and ST134, respectively. The blaCTX-M-15 gene was detected in P1 plasmid. P1 and P4 harboured the blaTEM-1 and blaOXA-1 genes. blaNDM-1 was found in P1, P3, and P4. No blaOXA-48, blaKPC, blaVIM, or blaIMP were identified. The plasmids were nontransferable and had IncFIB, IncFII, Col, and IncC incompatibility (Inc) groups . Class 1 integron was detected in all strains. Virulence genes related to biofilms, adhesins, siderophores (aerobactin, enterobactin, and salmochelin), intrinsic antimicrobial efflux pumps, secretory systems type I to VI, environmental and antibiotic stress response , outer membrane proteins, and heavy metal (copper, tellurite, arsenic, and zinc) resistance were found. The number of positive virulence factors was higher for P1 compared with other strains. Conclusion: The accumulation of AMR genes in Enterobacter spp. and their high endurance in hostile environments is a serious health problem. More genomic investigations are required to determine their AMR and virulence genetic reservoirs at the global level.

Abstract Background Extended-spectrum beta-lactamase-producing enterobacteria (ESBL-PE) in carriers have become a global health problem. Using molecular typing techniques, including PFGE, could be useful to determine the source of bacterial dissemination. The current study aimed to investigate the intestinal carriage of ESBL-producing E. coli (ESBL-EC) and clonal relatedness among ESBL-EC isolated from hospitalized and outpatient fecal carriers in Iran. Methods A total of 120 rectal swabs were collected; 50.8% (61/120) from intensive care unit (ICU) inpatients and 49.2% (59/120) from outpatients. MacConkey agar enriched with cefotaxime was used to screen the ESBL-EC. PCR assays were performed to detect ESBL and carbapenemase genes. Pulse-fields gel electrophoresis (PFGE) was performed to assess clonal relatedness. Results Totally, 60.0% (72/120) were carrier for ESBL-EC. The rates of resistance against ceftazidime and cefepime were 90.2% (65/72) and 93.0% (67/72), respectively. The rates of bla CTX-M-15, bla TEM, bla SHV, bla NDM-1, bla OXA-48 and bla IMP was 90.2% (65/72), 50.0% (36/72), 5.5% (4/72), 4.1% (3/72), 4.1% (3/72) and 1.3% (1/72), respectively. Based on a cut-off 80%, 69 ESBL-EC isolates could be categorized in 10 mini-cluster and 47 isolates were considered as singletons. Discussion High heterogeneity among isolates from ESBL-EC suggests that this bacterium probably has a different source of dissemination. Screening of carriers in hospitals and communities could help the infection control program in public health.

Abstract Pseudomonas aeruginosa as a common pathogen causing urinary tract infections (UTIs) has been resistant to different antibiotics and developing an effective vaccine can be an alternative strategy. In the present study, the immunogenicity and protection efficacy of formulations composed of a hybrid protein composed of P. aeruginosa V-antigen (PcrV) and exoenzyme S (ExoS) with alum and MPL were evaluated. The hybrid protein could increase the specific systemic and mucosal immune responses, as well as cellular responses as compared with control groups. Combining of alum or MPL adjuvant with the hybrid protein significantly improved the levels of IgG1, serum IgA, mucosal IgG, and IL-17 as compared to the ExoS.PcrV alone. After bladder challenge with a P. aeruginosa strain, the bacterial loads of bladder and kidneys were significantly decreased in mice received ExoS.PcrV admixed with alum and ExoS.PcrV admixed with MPL than controls. The present study indicated that immunization of mice with a hybrid protein composed of ExoS and PcrV could induce multifactorial immune responses and opsonize the bacteria and decrease the viable bacterial cells. Because P. aeruginosa have caused therapeutic challenges worldwide, our study proposed ExoS.PcrV + alum and ExoS.PcrV + MPL as promising candidates for the prevention of infections caused by P. aeruginosa.

Background: Gram-negative bacterial infections are on the rise due to the high prevalence of multidrug-resistant bacteria, and efforts must be made to identify novel drug targets and then new antibiotics. Methods: In the upstream part, we retrieved the genome sequences of 4 highly resistant Gram-negative bacteria (e.g., Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa , and Enterobacter cloacae ). The core proteins were assessed to find common, cytoplasmic, and essential proteins with no similarity to the human proteome. Novel drug targets were identified using DrugBank, and their sequence conservancy was evaluated. Protein Data Bank files and STRING interaction networks were assessed. Finally, the aminoacylation cavity of glycyl-tRNA synthetase (GlyQ) was virtually screened to identify novel inhibitors using AutoDock Vina and the StreptomeDB library. Ligands with high binding affinity were clustered, and then the pharmacokinetics properties of therapeutic agents were investigated. Results: A total of 6 common proteins (e.g., RP-L28, RP-L30, RP-S20, RP-S21, Rnt, and GlyQ) were selected as novel and widespread drug targets against highly resistant Gram-negative superbugs based on different criteria. In the downstream analysis, virtual screening revealed that Rimocidin, Flavofungin, Chaxamycin, 11,11′-O-dimethyl-14′-deethyl-14′-methylelaiophylin, and Platensimycin were promising hit compounds against GlyQ protein. Finally, 11,11′-O-dimethyl-14′-deethyl-14′-methylelaiophylin was identified as the best potential inhibitor of GlyQ protein. This compound showed high absorption capacity in the human intestine. Conclusion: The results of this study provide 6 common putative new drug targets against 4 highly resistant and Gram-negative bacteria. Moreover, we presented 5 different hit compounds against GlyQ protein as a novel therapeutic target. However, further in vitro and in vivo studies are needed to explore the bactericidal effects of proposed hit compounds against these superbugs.

Carbapanem-resistant Klebsiella pneumoniae is a globally healthcare crisis. The distribution of plasmids carrying carbapenemase genes among K. pneumoniae poses a serious threat in clinical settings. Here, we characterized the genetic structure of plasmids harboring major carbapenemases (e.g. blaKPC, blaNDM, blaOXA-48-like, and blaGES) from K. pneumoniae using bioinformatics tools. The plasmids carrying at least one major carbapenemase gene were retrieved from the GenBank database. The DNA length, Inc type, and conjugal apparatus of these plasmids were detected. Additionally, allele types, co-existence, co-occurrence of carbapenemase genes, gene repetition, and sequence types of isolates, were characterized. There were 2254 plasmids harboring carbapenemase genes in the database. This study revealed that blaKPC-2, blaNDM-1, blaOXA-48, and blaGES-5 were the most prevalent allele types. Out of 1140 (50%) plasmids were potentially conjugative. IncFII, IncR, IncX3, and IncL replicon types were predominant. The co-existence analysis revealed that the most prevalent of other resistance genes were blaTEM-1 (related to blaKPC), blaOXA-232 (related to blaOXA-48), bleMBL (related to blaNDM), and aac (6')-Ib4 (related to blaGES). The co-occurrence of carbapenemases was detected in 42 plasmids while 15 plasmids contained carbapenemase gene repetitions. Sequence alignments highlighted that plasmids carrying blaKPC and blaOXA-48-like were more homogeneous whereas the plasmids carrying blaNDM were divergent. It seems that K. pneumoniae utilizes diversity of genetic flexibility and recombination for resistance against carbapenems. The genetic structure of the plasmids showed that class I and III, Tn3 family, Tn5403 family derivatives, and Tn7-like elements were strongly associated with carbapenemases. The mobilizable plasmids carrying carbapenemases play an important role in the spread of these genes. In addition, gene repetition maybe is related to carbapenem heteroresistance. According to MST (minimum spanning tree) results, the majority of plasmids belonged to sequence type (ST) 11, ST14, and ST12. These international clones have a high capacity to acquire the carbapenemase-containing plasmids.

Background: Fusobacterium nucleatum is a Gram-negative bacterium that is found in the human oral cavity and plays a critical role in periodontal diseases. Due to the increasing resistance to antimicrobial agents, the development of an effective vaccine against this bacterium seems inevitable. Method: In the present study, we analyzed the whole genome of F. nucleatum ATCC 25586, and only extracellular, outer membrane and secreted proteins were selected for further investigation. Next, different properties of desired vaccine targets including allergenicity, antigenicity, homology to the human proteome and gut microbiota, B-cell epitopes, MHC-II binding sites, and prevalence among 30 clinical isolates, were determined. The quartile scoring method was used to select the best immunogenic targets. The network interaction of unknown function proteins with other proteins of F. nucleatum was characterized. Finally, the interactions of all putative immunogenic targets with human TLR-2 and TLR-4 were assessed, and the immune simulation were depicted. Results: According to the obtained results, eight proteins were selected as promising immunogenic targets. These proteins were hemin receptors, complement resistance proteins, lipoproteins, cell wall-associated proteins, and unknown function proteins. The prevalence of these proteins among 30 selected clinical strains was 100%. Hemin receptors and hypothetical protein FN0465 showed the strongest binding affinity to TLR-2 and TLR-4. Besides, hypothetical protein FN0465 induced the strongest immune response. Conclusion: This study presents eight novel immunogenic targets as putative vaccine candidates against F. nucleatum. Taken together, hemin receptors and hypothetical protein FN0465 showed better immunogenic properties which worth investigating in terms of immunoreactivity and pathogenesis in the future.

Background: Vibrio cholerae leads to severe acute watery diarrhea with a high mortality rate; owing to several virulence factors, especially the cholera toxin. Generally, gene duplication is a major evolutionary process that affects the environmental adaptation of bacteria. In this study, we aimed to investigate the repetitive virulence factors in V. cholera genomes. Method: Totally, 1530 genomes were collected and the possible duplication of 25 known virulence factors was assessed. Next, the genomes carrying duplicated cholera toxins (e.g. ctxA and ctxB) were further analyzed for the identification of novel repetitive virulence factors. All duplicated potential virulence proteins were classified based on clusters of orthologous groups (COGs) and their functions in different pathways were assessed. Results: Genome-wide analysis showed eight repetitive known virulence factors including rstA, ctxA, ctxB, zot, ace, espA, VC_RS09110, and mshA in V. cholerae genomes. It seems that the majority of the duplicated virulence factors are encoded on the CTXφ such as cholera toxin. Interestingly, our analysis revealed that fourteen genomes had simultaneously two copy numbers of ctxA and ctxB. The proteome of these strains harbored some repetitive proteins that resembled virulence factors of other bacteria. These duplicated proteins were mainly involved in replication, transcription, metabolism, and pathogenesis including Elongation factor Tu, Transketolase, Methyl-accepting chemotaxis protein, GNAT family N-acetyltransferases, cGAMP-activated phospholipase of Vibrio (CapV), HigA, and Helix-turn-helix transcriptional regulator. Conclusion: Surprisingly, a considerable number of duplicated genes have essential roles in the virulence and pathogenesis of V. cholerae. Moreover, it seems that novel duplicated genes had different roles in cellular processes or metabolic pathways.

Abstract Background Carbapenemase-producing Klebsiella pneumoniae (CP-KP) is becoming extensively disseminated in Iranian medical centers. Colistin is among the few agents that retains its activity against CP-KP. However, the administration of colistin for treatment of carbapenem-resistant infections has increased resistance against this antibiotic. Therefore, the identification of genetic background of co-carbapenem, colistin-resistance K. pneumoniae (Co-CCRKp) is urgent for implementation of serious infection control strategies. Methods Fourteen Co-CCRKp strains obtained from routine microbiological examinations were subjected to molecular analysis of antimicrobial resistance (AMR) using whole genome sequencing (WGS). Results Nine of 14 K. pneumoniae strains belonged to sequence type (ST)-11 and 50% of the isolates had K-locus type 15. All strains carried bla OXA-48 except for P26. bla NDM-1 was detected in only two plasmids associated with P6 and P26 strains belonging to incompatibility (Inc) groups; IncFIB, IncHI1B and IncFII. No bla KPC, bla VIM and bla IMP were identified. Multi-drug resistant (MDR) conjugative plasmids were identified in strains P6, P31, P35, P38 and P40. MICcolistin of K. pneumoniae strains ranged from 4 to 32 µg/ml. Modification of PmrA, PmrB, PhoQ, RamA and CrrB regulators as well as MgrB was identified as the mechanism of colistin resistance in our isolates. Single amino acid polymorphysims (SAPs) in PhoQ (D150G) and PmrB (R256G) were identified in all strains except for P35 and P38. CrrB was absent in P37 and modified in P7 (A200E). Insertion of ISKpn72 (P32), establishment of stop codon (Q30*) (P35 and P38), nucleotides deletion (P37), and amino acid substitution at position 28 were identified in MgrB (P33 and P42). None of the isolates were positive for plasmid-mediated colistin resistance (mcr) genes. P35 and P38 strains carried iutA, iucD, iucC, iucB and iucA genes and are considered as MDR-hypervirulent strains. P6, P7 and P43 had ICEKp4 variant and ICEKp3 was identified in 78% of the strains with specific carriage in ST11. Conclusion In our study, different genetic modifications in chromosomal coding regions of some regulator genes resulted in phenotypic resistance to colistin. However, the extra-chromosomal colistin resistance through mcr genes was not detected. Continuous genomic investigations need to be conducted to accurately depict the status of colistin resistance in clinical settings.

Abstract Background Productions of metallo-β-lactamases enzymes are the most common mechanism of antibiotic resistance to all beta-lactam classes (except monobactams) in Acinetobacter baumannii. MBLs are usually associated with gene cassettes of integrons and spread easily among bacteria. The current study was performed to detect the genes encoding MBLs and integron structures in A. baumannii isolates from burn patients. Methods This study was performed on 106 non-duplicate A. baumannii isolates from burn patients referred to Shahid Motahari Hospital in Tehran. Antibiotic susceptibility of A. baumannii isolates was performed using disk diffusion and broth microdilution method in accordance with the CLSI guidelines. The presence of class 1 integron and associated gene cassettes as well as MBLs-encoding genes including bla VIM, and bla IMP were investigated using PCR and sequencing techniques. Results In this cross-sectional study all (100%) of the A. baumannii isolates examined were multidrug resistant. All isolates were sensitive to colistin and simultaneously all were resistant to imipenem. PCR assays showed the presence of bla VIM and bla IMP genes in 102 (96.2%) and 62 (58.5%) isolates of A. baumannii respectively. In addition, 62 (58.5%) of the A. baumannii isolates carried integron class 1, of which 49 (79.0%) were identified with at least one gene cassette. Three types of integron class 1 gene cassettes were identified including: arr2, cmlA5, qacE1 (2300 bp); arr-2, ereC, aadA1, cmlA7, qacE1 (4800 bp); and aac(3)-Ic, cmlA5 (2250 bp). Conclusion A high prevalence of MBLs genes, especially bla VIM, was identified in the studied MDR A. baumannii isolates. In addition, most of the strains carried class 1 integrons. Furthermore, the gene cassettes arrays of integrons including cmlA5 and cmlA7 were detected, for the first time, in A. baumannii strains in Iran.

Abstract Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a pathogen of global concern. In this study, both phenotypic and genotypic tests were used to detect hvKp. Antimicrobial resistance profiles and clonal relatedness of clinical isolates were also determined. We found that 34.2% (163/477) of the isolates were tellurite resistant, and among them 102 hvKp isolates detected with iucA or iutA or peg-344 as molecular markers. The bla SHV (80.4%), followed by bla CTX-M-15 (76.5%) and bla TEM (67.6%), bla OXA-48 (53.9%), and bla NDM-1 (32.3%) were detected, while bla KPC-1 was not present in any hvKp isolates. It was found that the majority of hvKp isolates belonged to capsular serotype K20 and ompK36 group C, which is related to clonal group (CG) 23 (e.g. ST23). A high percentage of multidrug-resistant hvKp (76.6%) and high resistance to imipenem (67%) indicated a serious problem that should be addressed in the clinical setting.

Classical (CKp) and hypervirulent (hvKp) Klebsiella pneumoniae are two different circulating pathotypes. The aim of this study was to assess the prevalence, epidemiology and molecular relatedness of hvKps using a systemic review and meta-analysis. The data extracted from Medline, Embase, and Web of Science and finally 14 studies met the eligible criteria. To combine prevalence proportions of all studies, we performed the metaprop command embedded in the Meta package software. Totally, of 1814 K. pneumoniae isolates, 21.7% (394/1814) were hvKp. The molecular typing showed that all hvKp isolates were grouped into 50 different sequence types (STs) of them ST23, ST11, ST65 and ST86 were common. K1, K2 and K64 were dominant capsule serotypes that strongly related to ST23, ST65 and ST11, respectively. It seems that clonal group 23 (CG23) is associated with liver abscess and CG11 related to various clinical sources.

Hypervirulent Klebsiella pneumoniae (hvKp) pathotype is emerging worldwide in pyogenic liver abscesses (PLAs). However, the role of virulence factors in pathogenicity remains unclear. On the other hand, the epidemiology of PLAs in Iran is unknown. From July 2020 to April 2022, bacterial species were isolated and identified from the drainage samples of 54 patients with PLAs. K. pneumoniae as the most common pathogen of pyogenic liver abscesses was identified in 20 (37%) of the 54 patients. We analyzed the clinical and microbiological characteristics of K. pneumoniae-related pyogenic liver abscesses. Antibiotic susceptibility testes and string test were performed. 16S rRNA, antibiotic resistance, and virulence genes were determined by polymerase chain reaction amplification. Clonal relatedness of isolates was identified by multilocus sequence typing. Virulence levels were assessed in the Galleria mellonella larval infection model. Four hvKp isolates (K1/K2) were found to be responsible for cryptogenic PLAs, and 16 classical K. pneumoniae isolates (non-K1/K2) were associated with non-cryptogenic PLAs. Three capsular serotype K1 strains belonged to sequence type 23 (ST23) and one K2 strain to ST65. Meanwhile, the non-K1/K2 strains belonged to other STs. ST231 was the most common strain among the classical K. pneumoniae strains. Compared with the non-K1/K2 strains, capsular serotypes K1/K2 strains were less resistant to antibiotics, had positive string test results, and had more virulence genes. In Galleria mellonella, a concentration of 106 colony-forming units of the K1 hvKp strain resulted in 100% death at 24 hours, confirming the higher virulence of the hvKp strain compared with cKp. K. pneumoniae isolates represented that the acquisition of any plasmid or chromosomal virulence genes contributes to pathogenicity and high prevalence in PLAs. Meanwhile, hvKp isolates with a specific genetic background were detected in cryptogenic PLAs.

Introduction: The development of a vaccine against Staphylococcus aureus has proven to be much more difficult than expected. In this study, we considered and analyzed a mutant Toxic Shock Syndrome Toxin-1 (TSST-1) as a potential vaccine candidate. Methods: An NCBI sequence of TSST-1 was analyzed bioinformatically by online tools such as Ensemble and Pubmlst. The protein sequence of TSST-1 was similarly analysed by Expasy ProtParam, Phyre2 and Vaxign databases. The protein functional class was predicted by VICMpred database while the B- and T-cell epitopes were predicted by IEDB and BepiPred tools. The 3D structure was predicted by LOMETS, QMEAN, ProSA-web and ElliPro. The conservation of the epitopes was evaluated by ConSurf tool. Results: In silico analyses showed that this protein is present in high-prevalence sequence types of circulating clinical strains. It appears that TSST-1 has conserved liner and conformational B-cell epitopes. In addition, there are four potent of T-cell epitopes in this protein. Conclusion: This in silico data indicated that TSST-1 (and especially amino acid residues 81-221) is a promising vaccine target against S. aureus.

Introduction: Flagellin (FliC) is an essential and universal subunit of flagella in motile bacteria. Analysis of the sequence diversity of the FliC protein in the Enterobacteriaceae family may provide insight into the pathogenic strategy of these bacteria in the context of interaction with pathogen-associated molecular patterns (PAMPs). In addition, the efficacy of FliC as an adjuvant or a component of the multi-epitope vaccine has been demonstrated. Methods: We analyzed 392 full-length and non-redundant FliC proteins from the Enterobacteriaceae family. In the first step, isoelectric pH, molecular weight (kDa), and amino acid composition of FliC protein sequences were calculated using the ProtParam program. Next, the tertiary structure of the FliC proteins and its interaction with zebrafish TLR-5 was performed. Sequence alignments were performed using ClustalW software and the curricular phylogenetic tree was depicted using MEGA-7 software and iTOL web server. Finally, we evaluated the interaction of FliC proteins of Enterobacteriaceae family with TLR-5 to find the strongest docking. Results: Physicochemical properties and multiple sequence alignments revealed that FliC has a unique characterization in each genus. However, D1 as the binding domain site associated with TLR-5 exhibited high sequence conservation and the FliC protein of S. enterica subsp. enterica had the strongest interaction with TLR-5. Conclusions: FliC protein of S. enterica subsp. enterica can be consider as a promising epitope-delivery platform. In addition, phylogenetic analysis revealed that FliC may be acceptable marker for distinguishing genera in the family Enterobacteriaceae.

Background: Silver nanoparticles (AgNPs) were phyto-synthesized using Typha azerbaijanensis aerial part and root extracts, and their biological activities were investigated. Methods: This study was conducted in the Science and Research Branch, Islamic Azad University, Tehran, Iran in 2019. In this experimental study, silver nanoparticles (AgNPs) were phyto-synthesized and the physicochemical properties of AgNPs were determined using UV-Vis (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Antibacterial and anticancer activity of synthesized AgNPs was determined using microdilution assay, and MTT 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) methods, respectively. The apoptotic effects of AgNPs were investigated using Real-Time PCR and flow cytometry techniques. Results: Morphological analysis of the synthesized AgNPs confirmed the spherical shape of AgNPs with an average size of 10.67 to 16.69 nm. The FTIR spectrum confirmed the presence of phytochemicals from T. azerbayenensis extract at the AgNP surface. Antibacterial experiments showed that phyto-fabricated AgNPs had significant antibacterial activity against Gram-negative bacteria. The AgNPs were significantly cytotoxic against breast cancer cell line (MCF-7) through induction of apoptosis. Conclusion: The phyto-synthesized AgNPs had biological activities could be useful in pharmaceutical applications.

Porphyromonas gingivalis is a primary causative agent of chronic periodontitis. Moreover, it leads to several systemic diseases, including rheumatoid arthritis, cardiovascular, neurodegenerative, and Alzheimer's diseases. It seems that the development of a vaccine against this bacterium is necessary. Thus, this study decided to identify novel immunogenic targets and developed multiple epitope-based vaccines against P. gingivalis. For this purpose, the pan/core-proteome of this bacterium was studied, and the suitable vaccine targets were selected based on different properties, including exposed localization of proteins, antigenicity, non-allergenicity, non-similarity to host proteome, stability, B-cell epitopes and MHC II binding sites, sequence conservation, molecular docking, and immune simulation. Through the quartile scoring method, 12 proteins with ≥ 20 scores were considered as suitable immunogenic targets. The results of the protein domain and functional class search showed that most of the immunogenic proteins were involved in the transport and metabolism of inorganic ions and lipids. In addition, two unknown function proteins, including WP_004584259.1 and WP_099780539.1 were detected as immunogenic targets. Three constructions carrying multi-epitopes were generated including Naked, LCL, and as chimeric structures. Among them, FliC chimeric protein had the strongest affinity to the human TLR2, 4, and 6, while the LCL platform represented the highest level of immune stimulation response. The obtained results from this study revealed new insights into prophylactic routes against P. gingivalis by introducing novel immunogenic targets. However, further investigations, including site-directed mutation and immunoassay are needed to confirm the pathogenic role and protectivity of these novel proteins.

Background Enterobacter is a major nosocomial genus of Enterobacteriaceae responsible for a variety of nosocomial infections, particularly in prolonged hospitalized patients in the intensive care units. Since current antibiotics have failed treating colistin- and carbapenem-resistant Enterobacteriaceae, efforts are underway to find suitable alternative strategies. Therefore, this study conducted a reverse vaccinology (RV) to identify novel and putative immunogenic targets using core proteome of 20 different sequence types (STs) of clinical Enterobacter spp. Moreover, we introduced a structural-based approach for exploration of potential vaccine candidates against the Enterobacteriaceae family using their conserved domain analysis. Results A number of 2616 core coding sequences (CDSs) were retrieved from 20 clinical strains of Enterobacter spp. with a similarity of ≥ 50%. Nine proteins with a score of ≥ 20 considered as the shortlisted proteins based on the quartile scoring method, including three TonB-dependent receptors, WP_008500981.1, WP_058690971.1 and WP_058679571.1; one YjbH domain-containing protein, WP_110108068.1; three flagellar proteins, WP_088207510.1, WP_033145204.1 and WP_058679632.1; one spore-coat U domain-containing protein, WP_039266612.1; and one DD-metalloendopeptidase family protein, WP_025912449.1. In this study, proteins WP_058690971.1 and WP_110108068.1 were detected as the top candidates with regard to immune stimulation and interactions with TLRs. However, their efficacy is remaining to be evaluated experimentally. Conclusions Our investigation introduced common ferrichrome porins with high sequence similarity as potential vaccine candidates against the Enterobacteriaceae family. These proteins belong to the iron acquisition system and possess all criteria of suitable vaccine targets. Therefore, they need to be specifically paid attention for vaccine development against clinically important members of Enterobacteriaceae family.

Increasing antibiotic resistance of Acinetobacter baumannii highlights the urgent need to develop an effective vaccine to combat it. Despite all efforts, no approved vaccine against this bacterium is on the market, and attempts are underway to find effective vaccines. Due to their surface exposure, outer membrane proteins (OMPs) are excellent vaccine targets. The extracellular loops of OMPs are highly immunogenic. Therefore, in the present study, we aimed to detect the conserved, exposed, and immunogenic linear B-cell epitopes among sixty-five OMPs available in 35 A. baumannii genomes deposited in the Vaxign database. According to defined criteria (allergenicity, antigenicity, and non-similarity to host), four linear B-cell epitopes were selected as highly immunogenic peptides. Epitope shuffling was performed to select the best arrangements of these epitopes. We proposed six different multi-epitope vaccines consisting of two Naked arrangements, two loop-less C-lobe (LCL) structures, and two FliC-based constructs. An LCL-based multi-epitope vaccine showed the best molecular docking score with human TLRs (TLR 1, 2, 4, and 5) and immune simulation results (Th1 cell population, IFN-γ, IL-12, IgM, IgG1, and IgG2 levels). This study provided a valuable library of exposed epitopes including 26 conserved, linear and immunogenic B-cell epitopes (belonged to 14 OMPs), and three optimized multi-epitope vaccines. However, more experimental studies are needed to confirm the actual immunoreactivity of these vaccine candidates.

Carbapenem resistance in Enterobacterales is a major and persistent public health problem worldwide. In current research, we present data of 96 Enterobacterales species collected from a clinical hospital in Isfahan, Iran. The bacterial identification was performed by standard biochemical tests and API 20E methods. Agar disk diffusion assay was performed to determine the phenotypic antibiotic resistance of strains. Polymerase chain reaction (PCR) was carried out to detect carbapenemase genes. In this manuscript, multiple antimicrobial resistance phenotype such as multiple carbapenem resistance determinants were detected. The data would provide important information on distribution of carbapenemase genes of those pathogenic bacteria in Iran.

Tuberculosis (TB) is a sizable public health threat in the world. This study was conducted to determine the differential protein composition between susceptible and MDRTB strains. Tuberculosis proteins were extracted by Triton™ X-114 and ammonium sulfate. Two-dimensional gel electrophoresis protein spots were selected for identification by mass spectrometry and mRNA expression levels were measured by real- time PCR.2DE-Western blot and T cell epitope prediction for identified proteins were made by the IEDB server. The result shows at least six protein spots (Rv0147, Rv3597c, Rv0379, Rv3699, Rv1392 and Rv0443) were differentially expressed in MDRTB isolates. However, difference in mRNA gene expression was not found in the six mRNA genes.2DE-Western blot procedures indicated strong reaction against MDRTB proteins corresponds to 13, 16 and 55 kDa areas that might be used as new diagnostic tools. In conclusion, these MDRTB proteins identified in this study could be reliable TB diagnostic candidates or therapeutic targets.

Abstract Objectives The increasing prevalence of antibiotic‐resistant Staphylococcus aureus, besides the inadequate numbers of effective antibiotics, emphasises the need to find new therapeutic agents against this lethal pathogen. Methods In this study, to obtain antibody fragments against S. aureus, a human single‐chain fragment variable (scFv) library was enriched against living methicillin‐resistant S. aureus (MRSA) cells, grown in three different conditions, that is human peripheral blood mononuclear cells with plasma, whole blood and biofilm. The antibacterial activity of scFvs was evaluated by the growth inhibition assay in vitro. Furthermore, the therapeutic efficacy of anti‐S. aureus scFvs was appraised in a mouse model of bacteraemia. Results Three scFv antibodies, that is MEH63, MEH158 and MEH183, with unique sequences, were found, which exhibited significant binding to S. aureus and reduced the viability of S. aureus in in vitro inhibition assays. Based on the results, MEH63, MEH158 and MEH183, in addition to their combination, could prolong the survival rate, reduce the bacterial burden in the blood and prevent inflammation and tissue destruction in the kidneys and spleen of mice with MRSA bacteraemia compared with the vehicle group (treated with normal saline). Conclusion The combination therapy with anti‐S. aureus scFvs and conventional antibiotics might shed light on the treatment of patients with S. aureus infections.

Carbapenem-resistant Enterobacterales (CRE) is an increasing problem worldwide. Here, we examined the clonal relatedness of 71 non-repetitive CRE isolates collected in a university hospital in Tehran, Iran, between February 2015 and March 2016. Pulsed-field gel electrophoresis (PFGE) and MLST were used for epidemiological analysis. Screening for antibiotic resistance genes, PCR-based replicon typing, conjugation experiments, and optical DNA mapping were also performed. Among all 71 isolates, 47 isolates of Klebsiella pneumoniae (66.2%), eight Escherichia coli (11.2%), five Serratia marcescens (7%), and two Enterobacter cloacae (2.8%) harbored blaNDM–1 and blaOXA–48 genes together or alone. PFGE analysis revealed that most of the OXA-48- and NDM-1-producing K. pneumoniae and all of OXA-48-producing S. marcescens were clonally related, while all eight E. coli and two E. cloacae isolates were clonally unrelated. The predominant clones of carbapenemase-producing K. pneumoniae associated with outbreaks within the hospital were ST147 (n = 13) and ST893 (n = 10). Plasmids carrying blaNDM–1 and blaOXA–48 were successfully transferred to an E. coli K12-recipient strain. The blaOXA–48 gene was located on an IncL/M conjugative plasmid, while the blaNDM–1 gene was located on both IncFII ∼86-kb to ∼140-kb and IncA/C conjugative plasmids. Our findings provide novel epidemiologic data on carbapenemase-producing Enterobacterales (CPE) in Iran and highlight the importance of horizontal gene transfer in the dissemination of blaNDM–1 and blaOXA–48 genes. The occurrence and transmission of distinct K. pneumoniae clones call for improved infection control to prevent further spread of these pathogens in Iran.

ObjectivesPertussis remains endemic despite high vaccine coverage in infants and toddlers. Pertussis vaccines confer protection but immunity wanes overtime and boosters are needed in a lifetime. Iran, eligible for the Expanded Program on Immunization that includes the primary immunization, implemented two additional booster doses using a whole-cell vaccine (wPV) at 18 months-old and about 6 years-old. Duration of protection induced by the wPVs currently in use and their impact as pre-school booster are not well documented. This study aimed at assessing vaccination compliance and at estimating the duration of protection conferred by vaccination with wPV in children aged < 15 years in Tehran, Iran.MethodsDetailed information on vaccination history and capillary blood samples were obtained from 1047 children aged 3-15 years who completed the 3 doses-primary pertussis immunization, in Tehran. Anti-pertussis toxin IgG levels were quantified by ELISA.ResultsCompliance was very high with 93.3% of children who received the three primary and 1st booster doses in a timely manner. Timeliness of the 2nd booster was lower (63.3%). Rate of seropositive samples continuously and significantly increased from 1-2 to 5-6 years after 1st booster attaining 30.4% of children exhibiting serological sign of recent contact with B. pertussis. Second booster dating back 1 or 2 years was associated with high antibody titers, which significantly decreased within 3 years from injection. Among children who received 2nd booster injection more than 2 years before serum analysis, seroprevalence of pertussis infection was 8.4% and seropositivity rate was higher from the 10 years-old group.ConclusionSeropositivity in children aged 6-7 years with no 2nd booster supports the need for a vaccination at that age. Adolescent booster may also be considered.

Background and Objectives: Bordetella holmesii is associated with a pertussis-like respiratory syndrome in healthy individuals and also a rare cause of septicaemia, endocarditis, pneumonia, and septic arthritis, mostly in immunocompromised patients. Culture technique and real-time PCR are 2 methods used to detect Bordetella spp. Materials and Methods: In this study, 435 nasopharyngeal specimens of patients with suspected whooping cough were checked for the presence of B. holmesii using 2 methods of culture technique and real-time PCR. Results: In this study, we detected hIS1001 and IS481 of B. holmesii in 2 infants suspected of having pertussis-like syndrome. Conclusion: Our observations demonstrate that accurate diagnosis is needed to discriminate between B. holmesii and B. pertussis infections among pertussis cases; otherwise, it could lead to misestimating pertussis rate and vaccine efficacy.

Background: Acinetobacter baumannii is commonly resistant to nearly all antibiotics due to presence of antibiotic resistance genes and biofilm formation. In this study we determined the presence of certain antibiotic-resistance genes associated with biofilm production and the influence of low iron concentration on expression of the biofilm-associated protein gene (bap) in development of biofilm among multi-drug-resistant A. baumannii (MDRAB). Methods: Sixty-five MDRAB isolates from clinical samples were collected. Molecular typing was carried out by random amplified polymorphism DNA polymerase chain reaction (RAPD-PCR). Biofilm formation was assayed by the microtiter method. Results: The sequence of bap was determined and deposited in the GenBank database (accession no. KR080550.1). Expression of bap in the presence of low iron was analyzed by relative quantitative real time PCR (rqRT-PCR). Nearly half of the isolates belonged to RAPD-types A and B remaining were either small clusters or singleton. The results of biofilm formation revealed that 23 (35.4%), 18 (27.7%), 13 (20%), and 11 (16.9%) of the isolates had strong, moderate, weak, and no biofilm activities, respectively. ompA and csuE genes were detected in all, while bap and blaPER-1 were detected in 43 (66%) and 42 (64%) of the isolates that showed strong and moderate biofilm activities (p ≤ 0.05), respectively. Analysis of bap expression by rqRT-PCR revealed five isolates with four-fold bap overexpression in the presence of low iron concentration (20 μM). Conclusion: The results suggest that bap overexpression may influence biofilm formation in presence of low iron concentration.

Background and objectives: Klebsiella species are of the most common bacteria involved in nosocomial and urinary tract infections. Genetic elements such as class 1 integrons have an important role in the resistance development. In this study, the share of class 1 integrons, the genetic characterization of the integron cassettes and PFGE profiles of the clinical Klebsiella isolates are evaluated in Besat University hospital of Sanandaj, Iran. Methods: Isolates from 17890 clinical specimens were identified by API20E. Antibiotic susceptibility testing and MIC were done for MDR isolates. For investigating class 1 integrons and gene cassettes, PCR by intI1 integrase and 5΄-CS/3΄-CS were performed. Integrated gene cassettes were analyzed by PCR-RFLP and sequencing. Pulsed-Field Gel Electrophoresis was carried out for studying of clonality outbreak of isolates. Results: Thirty five Klebsiella spp. were isolated and included 29 K. pneumoniae and six K. oxytoca. All the isolates were susceptible to carbapenems while other antibiotics showed high resistant profile. In all Klebsiella spp. PCR for intI1 integrase and 5΄-CS/3΄-CS were positive (100%). Sequencing for prevalent bands of internal variable regions between 5΄-CS/3΄-CS showed arr-5, orfD-aacA4 and aad5- dfrA17. PFGE Analysis showed 18 clusters in K. pneumoniae with clonality relatedness in some cases but no relatedness among K. oxytoca isolates. Conclusion: High prevalence of class 1 integron carrying gene cassettes confirms that integron-mediated antimicrobial gene cassettes are important in Klebsiella spp. resistance profile. Clone diffusions of MDR Klebsiella spp. which harbor class 1 integrons have threaten the potential in the resistance development in our clinical settings.