Genomic Characterization of IMP-Producing Pseudomonas aeruginosa in Bulgaria Reveals the Emergence of IMP-100, a Novel Plasmid-Mediated Variant Coexisting with a Chromosomal VIM-4

Multidrug-resistant (MDR) Pseudomonas aeruginosa infections represent a major public health concern and require comprehensive understanding of their genetic makeup. This study investigated the first occurrence of imipenemase (IMP)-carrying P. aeruginosa strains from Bulgaria. Whole genome sequencing identified a novel plasmid-mediated IMP-100 allele located in a a novel In4886 integron embedded in a putative Tn7700 transposon. Two other closely related chromosomal IMP variants, IMP-13 and IMP-84, were also detected. The IMP-producers were resistant to last-line drugs including cefiderocol (CFDC) (two out of three) and susceptible to colistin. The IMP-13/84 cassettes were situated in a In320 integron inserted in a Tn5051-like transposon as previously reported. Lastly, the p4782-IMP plasmid rendered the PA01 transformant resistant to CFDC, suggesting a transferable CFDC resistance. A variety of virulence factors associated with adhesion, antiphagocytosis, iron uptake, and quorum sensing, as well as secretion systems, toxins, and proteases, were confirmed, suggesting significant pathogenic potential consistent with the observed strong biofilm formation. The emergence of IMP-producing MDR P. aeruginosa is alarming as it remains unsusceptible even to last-generation drugs like CFDC. Newly detected IMP-100 was even located in a CFDC-resistant XDR strain.

Co-existence of blaIMP, blaNDM-1, and blaSHV, genes of Pseudomonas aeruginosa isolated from Quetta: Antimicrobial resistance and clinical significance

Objective

Molecular detection and co-presence of carbapenem-resistant genes in the isolates of Pseudomonas aeruginosa are less commonly reported from Quetta. In the present study, we determined to highlight the antibiotic sensitivity profile and genetic mechanism of carbapenem resistance.

Methods

The cross-sectional study was conducted from May to September 2018 at the Hi-tech laboratory, Centre for Advance Studies in Vaccinology and Biotechnology, University of Baluchistan, Quetta. Biochemical and molecular methods were ascertained for the recognition of the isolates and minimum inhibitory concentration was performed using E-test and broth microdilution methods. The molecular basis of carbapenemase activity was determined by identifying carbapenemase genes in the isolates.

Results

Of the (n=23) P. aeruginosa isolated from pus aspirates obtained from surgical/burn units, we have detected blaIMP (n=7/8) 87.5%, blaNDM-1 (n=5/8) 62.5%, and blaSHV (n=4/8) 50%. The co-existence of multiple antibiotic-resistant genes, blaIMP, blaNDM-1 and blaSHV was found in (n=2/8) 25% isolates. These isolates displayed resistance against a range of antimicrobials from β-lactams, tetracyclines, cephalosporins, quinolones, monobactams, aminoglycosides, sulphonamides, phosphoric acid, macrolides, and polypeptide groups, suggesting extensive-drug resistance.

Conclusion

The emergence of MBL and ESBL producers is an alarming threat in the region. It is of great importance to determine the resistance mechanism of bacterial bugs. The lack of new antimicrobials particularly against gram-negative bacteria is quite alarming worldwide.

Susceptibility of ceftolozane/tazobactam against multidrug-resistant and carbapenem-resistant Pseudomonas aeruginosa

Ceftolozane (CTLZ) is a novel cephalosporin antibiotic that exhibits broad-spectrum activity against gram-negative pathogens, including Pseudomonas aeruginosa, especially when combined with tazobactam (TAZ). We examined the minimum inhibitory concentration (MIC) of CTLZ/TAZ for 21 multidrug-resistant P. aeruginosa (MDRP) and eight carbapenem-resistant P. aeruginosa (CRPA) strains isolated at Okayama University Hospital, Japan. Consequently, 81% (17/21) of the MDRP strains and 25% (2/8) of the CRPA strains were resistant to CTLZ/TAZ (MIC >8 μg/mL). All 18 blaIMP-positive strains showed resistance to CTLZ/TAZ, whereas the drug retained in vitro susceptibility in 54.5% (6/11 strains) of blaIMP-negative strains.

Genotypic Characterization of Carbapenem-Resistant Klebsiella pneumoniae Isolated from an Egyptian University Hospital

Globally, Klebsiella pneumoniae (K. pneumoniae) has been identified as a serious source of infections. The objectives of our study were to investigate the prevalence of multidrug-resistant (MDR) K. pneumoniae in Tanta University Hospitals, Gharbia Governorate, Egypt; characterize their carbapenem resistance profiles; and identify their different capsular serotypes. We identified and isolated 160 (32%) K. pneumoniae from 500 different clinical samples, performed antimicrobial susceptibility testing, and then used multiplex PCR to detect carbapenemase genes and capsular serotypes K1, K2, K3, K5, K20, K54, and K57. We detected phenotypic carbapenem resistance in 31.3% (50/160) of the isolates; however, molecular assays revealed that 38.75% (62/160) of isolates were carrying carbapenemase-encoding genes. Generally, blaOXA-48 was the prevalent gene (15.5%), followed by blaVIM (15%), blaIMP (7.5%), blaKPC (4%), and blaNDM (3.8%). BlaVIM and blaOXA-48 correlated with phenotypic resistance in 91.67% and 88% of the isolates that harbored them, respectively. Capsular typing showed that the most prevalent pathotype was K1 (30.6%), followed by K57 (24.2%), K54 (19.35%), K20 (9.67%), and K2 (6.45%). A critical risk to community health is posed by the high incidence of multidrug-resistant (MDR) virulent K. pneumoniae isolates from our hospital, and our study examines this pathogen's public health and epidemiological risks.

Phenotypic and genotypic investigation of metallo-β-lactamases in Pseudomonas aeruginosa clinical isolates in Bushehr, Iran

Objectives

Production of metallo-β-lactamases (MBLs) is an important mechanism of resistance to carbapenems. This study aimed to detect the MBL-producing Pseudomonas aeruginosa clinical isolates and to investigate the presence of bla _VIM, bla _IMP, bla _SPM, bla _NDM, bla _GIM, bla _AIM, and bla _SIM genes in these isolates in Bushehr, Iran.

Materials and Methods

A total of 169 P. aeruginosa clinical isolates were collected from three hospitals in Bushehr. The modified carbapenem inactivation method (mCIM) was used for the phenotypic detection of carbapenemase production. A combination disk test (CDT) was performed for the phenotypic detection of MBL production. To investigate the presence of bla _VIM, bla _IMP, bla _SPM, bla _NDM, bla _GIM, bla _AIM, and bla _SIM genes, PCR and sequencing was carried out.

Results

Based on the results of mCIM, 40 (23.7%) of 169 isolates were carbapenemase producers. CDT revealed that 26 (15.4%) isolates were MBL producers. bla _IMP, bla _NDM, and bla _VIM genes were found in 18 (69.2%), 8 (30.8%), and 1 (3.8%) of the MBL-producing isolates, respectively. Coexistence of bla _IMP and bla _NDM was observed in 2 (7.7%) MBL-producing isolates. Among all 169 P. aeruginosa isolates, 23 (13.6%) harbored bla _NDM, 18 (10.6%) carried bla _IMP, and 1 (0.6%) carried the bla _VIM gene. bla _SPM, bla _GIM, bla _AIM, and bla _SIM were not found in the present study.

Conclusion

bla _NDM, bla _IMP, and bla _VIM genes were detected in this study, which could be a warning sign about the prevalence of these genes among P. aeruginosa clinical isolates in our region. Proper monitoring and detection of MBL-producing isolates are essential steps to prevent the spread of these isolates.

Association of Biofilm Inducer with bla VIM, bla IMP, and bla NDM in Pseudomonas aeruginosa Isolates

Pseudomonas aeruginosa (P. aeruginosa) is a ubiquitous opportunistic organism that is hard to treat. This study aimed to investigate the association of bla _VIM, bla _IMP, and bla _NDM prevalence with Cyclic di-GMP (c-di-GMP) in P. aeruginosa. To this end, 27 clinical isolates of P. aeruginosa were obtained from different hospitals in Baghdad, Iraq. The phenotypic detection of carbapenem and biofilm assays was performed by the M63 minimal medium, supplemented with glucose, magnesium sulfate. The polymerase chain reaction was utilized to detect carbapenem genes. The results showed that the isolates were highly resistant to Imipenem (37%) and Meropenem (63%). Imipenem (37%) and Meropenem (63%) demonstrated a moderate sensitivity against P. aeruginosa. The P. aeruginosa No.5 showed high resistance to carbapenem by bla _VIM ⁺, bla _IMP ⁺, and bla _NDM ⁺, followed by a robust biofilm confirmed with c-di-GMP levels and the twitching motility ability. Upon these findings, the use of antibiotics should be restricted to severe bacterial infections to avoid the rapid emergence of new resistant isolates, which leads to the hard treatment of infection with P. aeruginosa. It is highly recommended that these findings be notified for infectious control. Future studies can investigate the link between transferable resistant genes and c-di-GMP values.

Genetic diversity and molecular analysis of metallo beta lactamases among imipenem resistant clinical isolates of Pseudomonas aeruginosa from Peshawar, Pakistan

Objectives

Pseudomonas aeruginosa is an opportunistic pathogen with remarkable adaptation ability to thrive in diverse environmental conditions. This study aimed at phenotypic and molecular analysis of metallo beta lactamases (blaIMP, blaVIM, blaNDM-1 and blaSPM-1) and genetic diversity analysis among imipenem resistant clinical isolates of Pseudomonas aeruginosa.

Methods

This study was conducted from May 2017 to June 2018. The study included 187 Pseudomonas aeruginosa isolates collected from different clinical specimens from Peshawar, Pakistan. The isolates were analyzed for resistance to imipenem. Combined disc test (CDT) was then performed for phenotypic detection of metallo beta lactamases among imipenem resistant isolates of Pseudomonas aeruginosa. Molecular detection of metallo beta lactamases genes i.e. blaIMP, blaVIM, blaNDM-1 and blaSPM-1 was analyzed through polymerase chain reaction. Genetic diversity was determined through RAPD-PCR.

Results

MBL production was observed in 76% (n=19) isolates. The occurrence of MBL genes blaIMP, blaNDM-1 and blaVIM was 68% (n=17), 48% (n=12), and 4% (n=1) respectively. The blaSPM-1 gene was not detected. High genetic diversity was observed in current study. Out of 182 isolates 171 isolates showed different RAPD profiles (93.95% polymorphism); 160 were unique RAPD strains and based on similarity coefficient ≥ 80%, 22 isolates were clustered into 11 distinct clones.

Conclusion

A high prevalence of blaIMP and blaNDM-1 among imipenem resistant isolates of Pseudomonas aeruginosa is alarming that calls for proper control and prevention strategies. RAPD technique was found to be a good genotyping technique when limited resources are available.

Clonal Dissemination of Multiple Carbapenemase Genes in Carbapenem-Resistant Enterobacterales Mediated by Multiple Plasmids in China

Background

Carbapenem-resistant Enterobacterales (CRE) are rapidly increasing worldwide in last two decades and lead few antibiotics for treatment. The molecular epidemiology of CRE in China was investigated to provide basis for clinical rational use of antibiotics and prevent its spread.

Methods

All CRE isolates in this study were collected from 11 hospitals from October 2015 to July 2018. The isolates were subjected to antimicrobial susceptibility tests, PCR molecular identification, pulsed-field gel electrophoresis, and multilocus sequence typing.

Results

Among the 399 CRE isolates, 51.6% (206/399) harbored carbapenemase genes. Three carbapenemase genes were detected, namely bla _KPC-2, bla _NDM-1, and bla _IMP at rates of 29.8% (119/399), 17.5% (70/399), and 4.0% (16/399), respectively. In Klebsiella pneumoniae (350) and Escherichia coli (26), bla _KPC-2 (33.4%, 117/350) and bla _NDM-1 (61.5%, 16/26) were the predominant genes. The most common genes in the CRE isolates were bla _KPC (85.5%) and bla _NDM-1 (76.5%) from adults and children, respectively. Particularly, ST11 K. pneumoniae with bla _KPC-2 harbored by IncFII plasmids were distributed in both general and primary hospitals, suggesting a clonal transmission pattern at these sites. In addition, the clonal distribution of ST2407 K. pneumoniae with bla _NDM-1 located on IncX3 plasmids and bla _IMP-38-positive ST307 K. pneumoniae were detected in a children's hospital.

Conclusion

The distribution of carbapenemase genes differed among strains and age groups. Multiple carbapenemase genes in the CRE strains were clonally disseminated in the tested regions mediated by multiple plasmids. Therefore, CRE monitoring should be increased and measures should be adopted to prevent its transmission.

Design of Rapid Detection System for Five Major Carbapenemase Families (bla KPC, bla NDM, bla VIM, bla IMP and bla OXA-48-Like) by Colorimetric Loop-Mediated Isothermal Amplification

Purpose

Carbapenemase-producing Enterobacteriaceae (CPE) infection constitutes a public health threat. Timely and efficient diagnosis is of paramount importance for prompt and effective therapy. In order to quickly and comprehensively detect the five major families of carbapenemases (bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48-like), colorimetric loop-mediated isothermal amplification (LAMP) was employed.

Materials and Methods

Five sets of LAMP primers were designed, each of which can, respectively, amplify all the carbapenemase subtypes described in this work. Twenty whole genome sequencing-verified-“standard strains”, including 1 bla_NDM-1, 1 bla_NDM-5, 1 bla_NDM-6, 1 bla_NDM-7, 2 bla_IMP-4, 1 bla_IMP-8, 2 bla_KPC-2, 1 bla_KPC-3, 1 bla_KPC-4, 1 bla_KPC-5, 1 bla_KPC-6, 1 bla_KPC-7, 1 bla_OXA-48 and 1 bla_OXA-181 carrier, and 1 bla_VIM and bla_OXA-244, 1 bla_KPC-2 and bla_IMP-4, 1 bla_KPC-2 and bla_VIM-1 and 1 bla_KPC-2 and bla_NDM-1-co-carriers, were used to establish a 25-microliter visual LAMP reaction system (kept at 65°C for 30 minutes in water bath). Color change from bright pink to yellow indicated positive amplification. In addition, 126 pre-verified clinical carbapenem-resistant Enterobacteriaceae (CRE) isolates, including 65 CPE (23 bla_NDM, 2 bla_OXA-48-like, 1 bla_KPC and bla_VIM, 2 bla_IMP, and 37 bla_KPC carriers) and 61 non-CPE, were also detected.

Results

With the lowest detection limit of 10 colony forming units (CFU) per reaction for LAMP and 10³ CFU per reaction for PCR, the LAMP system demonstrated dramatically higher sensitivity while retaining the same specificity. Furthermore, we demonstrated concordant results between the two methods for the 126 clinical isolates.

Conclusion

Therefore, LAMP could be used for rapid identification of the five major carbapenemase gene families in routine clinical laboratories.

Genotypic to Phenotypic Resistance Discrepancies Identified Involving β-Lactamase Genes, blaKPC, blaIMP, blaNDM-1, and blaVIM in Uropathogenic Klebsiella pneumoniae

Introduction

Klebsiella pneumoniae carbapenemase (KPC) belongs to the Group-A β-lactamases that incorporate serine at their active site and hydrolyze various penicillins, cephalosporins, and carbapenems. Metallo-beta-lactamases (MBLs) are group-B enzymes that contain one or two essential zinc ions in the active sites and hydrolyze almost all clinically available β-lactam antibiotics. Klebsiella pneumoniae remains the pathogen with the most antimicrobial resistance to KPC and MBLs.

Methods

This research investigated the blaKPC, and MBL genes, namely, blaIMP, blaVIM, and blaNDM-1 and their phenotypic resistance to K. pneumoniae isolated from urinary tract infections (UTI) in Bangladesh. Isolated UTI K. pneumoniae were identified by API-20E and 16s rDNA gene analysis. Their phenotypic antimicrobial resistance was examined by the Kirby-Bauer disc diffusion method, followed by minimal inhibitory concentration (MIC) determination. blaKPC, blaIMP, blaNDM-1, and blaVIM genes were evaluated by polymerase chain reactions (PCR) and confirmed by sequencing.

Results

Fifty-eight K. pneumoniae were identified from 142 acute UTI cases. Their phenotypic resistance to amoxycillin-clavulanic acid, cephalexin, cefuroxime, ceftriaxone, and imipenem were 98.3%, 100%, 96.5%, 91.4%, 75.1%, respectively. Over half (31/58) of the isolates contained either blaKPC or one of the MBL genes. Individual prevalence of blaKPC, blaIMP, blaNDM-1, and blaVIM were 15.5% (9), 10.3% (6), 22.4% (13), and 19% (11), respectively. Of these, eight isolates (25.8%, 8/31) were found to have two genes in four different combinations. The co-existence of the ESBL genes generated more resistance than each one individually. Some isolates appeared phenotypically susceptible to imipenem in the presence of blaKPC, blaIMP, blaVIM, and blaNDM-1 genes, singly or in combination.

Conclusion

The discrepancy of genotype and phenotype resistance has significant consequences for clinical bacteriology, precision in diagnosis, the prudent selection of antimicrobials, and rational prescribing. Heterogeneous phenotypes of antimicrobial susceptibility testing should be taken seriously to avoid inappropriate diagnostic and therapeutic decisions.

Dissemination of Carbapenemases (KPC, NDM, OXA-48, IMP, and VIM) Among Carbapenem-Resistant Enterobacteriaceae Isolated From Adult and Children Patients in China

This study aimed to investigate the dissemination and characteristics of bla_KPC, bla_NDM, bla_OXA-48-like , bla_IMP, and bla_VIM among the carbapenem-resistant Enterobacteriaceae (CRE) strains isolated from adult and children patients. A total of 935 non-duplicate CRE strains were collected from 36 hospitals in 24 provinces or cities across China from 2016 to 2018. Antimicrobial susceptibility testing was performed by broth microdilution method and carbapenemase genes bla_KPC, bla_NDM, bla_OXA-48-like , bla_IMP, and bla_VIM were screened by PCR and confirmed by DNA sequencing. Overall, carbapenemases were produced in 97.4% (911/935) of CRE strains, including KPC-2 (51.6%, 482/935), NDM (35.7%, 334/935), and OXA-48-like carbapenemases (7.3%, 68/935). Overall, the most prevalent carbapenemase gene was bla_KPC-2 among Klebsiella pneumoniae (64.6%, 457/709) and the CRE strains isolated from adult patients (70.3%, 307/437), and bla_NDM among Escherichia coli (96.0%, 143/149) and the CRE strains from children (49.0%, 247/498). The bla_OXA-232-positive carbapenem-resistant K. pneumoniae (9.3%, 66/709) were all isolated from children. Sixteen strains were positive for bla_IMP and 9 strains produced multiple carbapenemases. No strain was positive for bla_VIM. Most of the CRE strains (>90%) were resistant to cephalosporins and carbapenems, more than half (>50%) were resistant to aminoglycosides and fluoroquinolones, but the majority (95.8 and 98.4%) were susceptible to polymyxin B and tigecycline. Ceftazidime-avibactam showed excellent in vitro activity against bla_KPC-2 and bla_OXA-48-like positive strains (100% susceptible). In China, KPC-2, NDM, and OXA-48-like carbapenemases were predominant among CRE clinical isolates. The most prevalent carbapenemase gene was bla_KPC-2 among K. pneumoniae isolates from adult patients, and bla_NDM among E. coli isolates from children.

Detection of VIM-1, VIM-2 and IMP-1 metallo- β-lactamase genes in Klebsiella pneumoniae isolated from clinical samples in Sanandaj, Kurdistan, west of Iran

BACKGROUND AND OBJECTIVES

Klebsiella pneumoniae is an important cause of serious nosocomial infections among Gram-negative bacteria. The aim of this study was evaluating the prevalence of VIM-1, VIM-2, and IMP-1 metallo-β-lactamase genes in clinical specimens at two teaching hospitals in Sanandaj, Kurdistan west of Iran.

MATERIALS AND METHODS

Four hundred different clinical specimens were collected from hospitalized patients or referred to hospitals from May 2013 to March 2014 in Sanandaj, Kurdistan, Iran. MBLs - producing K. pneumoniae detected by Double Disk Synergy Test. The MBL positive isolates were examined for the presence of VIM-1, VIM-2 and IMP-1 genes using PCR technique.

RESULTS

Of four hundred clinical specimens, 114 K. pneumoniae isolates were identified. Twenty-eight (24.6%) isolates were resistant to imipenem and 15 strains (53.6%) were positive for MBL enzymes production. PCR results showed VIM-1 and IMP-1 genes frequencies are 4 (26.7%) and 1 (6.7%). Only one strain of K. pneumoniae was found to be MBL producer among the outpatients.

CONCLUSION

The study results exhibited a high level of resistance to most of the antibiotics tested and high prevalence of MBLs producing in K. pneumoniae at two hospitals. Thus, the infection control methods and the implementation of antibiotic agents should be taken into account.

Association of the genes encoding Metallo-β-Lactamase with the presence of integrons among multidrug-resistant clinical isolates of Acinetobacter baumannii

Background: Metallo-β-Lactamases (MBL) are usually encoded on the gene cassettes harboring integrons and disseminated easily among Acinetobacter baumannii isolates. This study was aimed to investigate the association of the genes encoding MBL with the presence of class 1 and 2 integrons among multidrug-resistant (MDR) A.baumannii isolates.

Methodology: A total of 85 non-duplicated A.baumannii isolates were collected and evaluated for the amplification of bla_OXA-51. The presence of genes encoding MBLs, including bla_IMP, bla_VIM, bla_SIM, bla_SPM, bla_GIM, bla_DIM and bla_NDM, as well as intI 1 and intI 2 was evaluated by PCR. Also, the production of MBLs was screened phenotypically by the combination of EDTA and meropenem.

Results: In this study, 77 out of 85 isolates were MDR. Also, 34 isolates had only intI 1, 10 had only intI 2 and 15 had both intI 1 and intI 2. The phenotypic detection of MBLs was found in 30 isolates, among which bla_VIM was as the most common the gene encoding MBL followed by bla_IMP, bla_SPM and bla_SIM. The gene cassettes analysis revealed that class 1 integron is often responsible for transferring the genes harboring MBLs.

Conclusion: The production of MBLs among A. baumannii strains is one of the main mechanisms of resistance to carbapenems. Therefore, the development of inexpensive screening methods for the phenotypic detection of MBLs in clinical laboratories settings is essential. Also, our data revealed that the class 1 integron is often responsible for the dissemination of the MBL genes among A. baumannii isolates.

Detection of plasmid-mediated colistin-resistant and carbapenem-resistant genes by multiplex PCR

A multiplex PCR was described to simultaneously detect mcr-1 and frequently occurring carbapenem-resistant genes including bla_KPC, bla_NDM, bla_IMP, and bla_OXA-48-like in a single reaction. The PCR product sizes of these 4 carbapenem-resistant genes were 232 bp, 438 bp, 621 bp, and 798 bp for bla_IMP, bla_OXA-48-like, bla_NDM, and bla_KPC, respectively, whereas mcr-1 revealed 1126 bp of PCR product. This protocol accurately detected those resistant genes in agreement with the reference strains, 127 local carbapenem-resistant Enterobacteriaceae, 8 mcr-1 carrying Enterobacteriaceae, and 62 carbapenem-susceptible Enterobacteriaceae. This method will be useful for laboratory application and surveillance of carbapenem and/or colistin-resistant bacteria.

Molecular detection of blaNDM-1 (New Delhi metallobetalactamase-1) in nosocomial Enterobacteriaceae isolates by nested, multiplex polymerase chain reaction

BACKGROUND

Carbapenems are considered "drugs of last resort" in many life-threatening infections. Advent of carbapenemases like KPC, OXA-48, VIM, IMP, and NDM have greatly affected the efficacy of these drugs, posing serious threat to global health and infection control. NDM bears special significance to the India subcontinent, labeled as place of origin and reservoir. NDM tends to escape detection by routine phenotypic methods, requiring molecular confirmation. This study utilizes nested, multiplex polymerase chain reaction (PCR) for reliable detection of bla_NDM-1 in nosocomial Enterobacteriaceae isolates.

METHODS

This study was conducted to detect prevalence of bla_NDM-1, bla_IMP, bla_VIMand bla_KPC genes by multiplex PCR among multidrug/carbapenem-resistant nosocomial Enterobacteriaceae isolates. From March 2013 to April 2014, 100 consecutive non-repeat isolates of Enterobacteriaceae from various inpatient clinical samples were analyzed. Imipenem-resistant isolates identified by Kirby Bauer disk diffusion method with Clinical and Laboratory Standards Institute guidelines were further subjected to nested, multiplex PCR to simultaneously detect bla_NDM-1, bla_IMP, bla_VIMand bla_KPC genes.

RESULTS

Out of 100 isolates, 17 (17%) were found to be imipenem-resistant. bla_NDM-1 was detected in all 17 isolates by nested, multiplex PCR. bla_VIM was co-carried in 4 isolates while one isolate co-harbored bla_IMP with bla_NDM-1. Imipenem resistance and NDM-1 carriage was predominant amongst Klebsiella isolates. Maximum NDM-1 producers were isolated from the intensive care unit (70.6%).

CONCLUSION

NDM-1 prevalence in nosocomial Enterobacteriaceae isolates in our hospital was found to be 17%. A nested, multiplex PCR was used for rapid detection of various carbapenemase genes with high sensitivity and specificity which is essential not only for favorable patient outcome but also for timely implementation of appropriate infection control practices to prevent further spread of such organisms.

Sequencing of blaIMP-Carrying IncN2 Plasmids, and Comparative Genomics of IncN2 Plasmids Harboring Class 1 Integrons

This work presents the complete nucleotide sequences of p0801-IMP from Klebsiella pneumoniae, p7121-IMP from K. oxytoca, and p17285-IMP from Citrobacter freundii, which are recovered from three different cases of nosocomial infection. These three plasmids represent the first fully sequenced bla_IMP-carrying IncN2 plasmids. Further comparative genomics analysis of all the five integron-carrying IncN2 plasmids p0801-IMP, p7121-IMP, p17285-IMP, pJIE137, and p34983-59.134kb indicates that they possess conserved IncN2 backbones with limited genetic variations with respect to gene content and organization. Four class 1 integrons (bla_IMP-1-carrying In1223 in p0801-IMP/p7121-IMP, bla_IMP-8-carrying In655 in p17285-IMP, In27 in pJIE137, and In1130 in p34983-59.134kb), two insertion sequence-based transposition units (ISEcp1-orfRA1-14 in p17285-IMP, and ISEcp1-bla_CTX-M-62-Δorf477-orfRA1-14 in pJIE137), and a novel Tn1696-related transposon Tn6325 carrying In1130 in p34983-59.134kb are indentified in the plasmid accessory regions. In1223 and In655 represent ancestral Tn402-associated integrons, while In27 and In1130 belong to complex class 1 integrons. The relatively small IncN2 backbones are able to integrate different mobile elements which carry various resistance markers, promoting the accumulation and spread of antimicrobial resistance genes among enterobacterial species.

blaVIM and blaIMP Genes Detection in Isolates of Carbapenem Resistant P. aeruginosa of Hospitalized Patients in Two Hospitals in Iran

BACKGROUND & OBJECTIVE

Beta-lactam antibiotics resistance specifically Imipenem and Meropenem, the last choices of treatment, causes fatal events in patients with P.aeruginosa infection. The aim of this study was to detect the VIM and IMP of metallo-beta-lactamase genes in 103 isolates of P. aeruginosa in two Iranian hospitals.

METHODS

In this study, we evaluated the susceptibility of P. aeruginosa to a range of β-lactam antibiotics using disk diffusion method as a standard biochemical test. Combined disk test of Imipenem (IMP) and Imipenem plus Ethylenediaminetetraacetic acid (EDTA) was performed as a phenotypic method to find metallo-beta-lactamase producing isolates.Using conventional PCR method; we evaluated VIM and IMP of metallo-beta-lactamase (MBL) genes in 103 isolates of P.aeruginosa.

RESULTS

Twenty six (25.2%) out of 103 isolates were resistant to Imipenem and 26 (25.2%) to Meropenem. Among 26 Imipenem and Meropenem-resistant strains (25.2%), 19 cases (73.0%) were MBL producing. Using PCR method, we detected the bla_VIM and bla_IMP genes in 6 (5.8%) and 2(1.9%) of 19 MBL producing isolates, respectively.

CONCLUSIONS

Evaluation of these carbepenemases genes improve epidemiologic researches and also, can be used as a diagnostic tool for discriminating between antibiotics resistant and sensitive strains of P.aeruginosa as well as follow-up the patients after treatment.