Abstract

DETECTION OF CARBAPENEM RESISTANCE GENES IN E.COLI IN A TERTIARY CARE HOSPITAL

Dr. Atul Khajuria* and Ashok K. Praharaj

ABSTRACT

Objective: To examine the distribution, emergence and spread of genes encoding beta-lactamase resistance in E.coli recovered from hospitalized patients in a tertiary care hospital. Methods: A prospective study was conducted in an 1800 bedded tertiary care centre in Pune, India from October 2013 to October 2017. A total of 1070 E.coli isolates were recovered from clinical specimens of hospitalized patients admitted to the Medical and Surgical intensive care units (one isolate per patient). Polymerase chain reaction (PCR) assays and sequencing was used to determine the presence of beta-lactamase encoding genes and conjugation experiments were performed to determine the transferability. Isolate relatedness were determined by REP PCR, ERIC PCR and RAPD. Results: Majority of Carbapenem resistant E.coli were from UTIs 90 (40%), followed by SSTIs 45(20%), 18% (40) in RTIs, 30(13%) in BSIs and 21(9%) in IAIs respectively. Evaluation of antibiotic susceptibility pattern indicated that 21% E.coli were resistant against IPM, MEM, and ETP. Out of 1070 isolates, 226 were found carbapenem resistant as MICs was >4μg/ml against IPM, MEM, and ETP as determined by the E-test and VITEK-2, 185 were MBL producers and 41 were non MBL producers. In the present study, among carbapenem producers blaNDM-1was detected in 67.7% isolates, while blaVIM was present in 14.3% isolates, blaCTX-M was present in 89% isolates, followed by blaTEM-1 in 81% and blaSHV in 69.2%. In this study, blaSHV-5, blaSHV-11, blaSHV-12, and blaSHV-28 are the commonest SHV genes detected in 8%, 10.1%, 37.5% and 48.5% of blaSHV producing isolates respectively whereas blaCTX-M-15, blaCTX-M-14 and blaCTX-M-28 are the commonest CTX-M ESBLs that were present in 64.2%, 23% and 12.8% of blaCTX-M producing isolates respectively suggesting co association of multiple variants of ESBL along with MBLs that aids in marked increase in MICS against cephalosporins and other beta lactams including carbapenems and thereby increasing antimicrobial resistance towards commonly used drugs. Susceptibility profiling of the isolates indicated that 100% retained susceptibility to colistin. Conjugation experiments indicated that blaNDM-1,blaVIM, blaOXA-48, blaSHV-5, blaSHV-11, blaSHV-12, blaSHV-28, blaCTX-M-15, blaCTX-M-14 were transferable via plasmid. Conclusion: This study highlights prevalence of blaOXA-48 and blaNDM-1, producing E.coli in multiple combinations with other β-lactamases which are commonly found a single or multiple plasmids to serve as driving force for the horizontal spread of emerging carbapenem resistance that are critically important for treatment of human bacterial infections.

Keywords: BlaNDM-1, blaVIM, blaSHV-5, blaSHV-11, blaSHV-12, blaSHV-28, blaCTX-M-15, blaCTX-M-14, REP PCR, ERIC PCR and RAPD.