Characterization of Multidrug Resistant ESBL‐Producing Escherichia coli Isolates from Hospitals in Malaysia

King-Ting Lim,Savithri Puthucheary,Rohani Yasin,Kwai-Lin Thong,Chew-Chieng Yeo

doi:10.1155/2009/165637

Abstract

The emergence of Escherichia coli that produce extended spectrum β-lactamases (ESBLs) and are multidrug resistant (MDR) poses antibiotic management problems. Forty-seven E. coli isolates from various public hospitals in Malaysia were studied. All isolates were sensitive to imipenem whereas 36 were MDR (resistant to 2 or more classes of antibiotics). PCR detection using gene-specific primers showed that 87.5% of the ESBL-producing E. coli harbored the blaTEM gene. Other ESBL-encoding genes detected were blaOXA, blaSHV, and blaCTX-M. Integron-encoded integrases were detected in 55.3% of isolates, with class 1 integron-encoded intI1 integrase being the majority. Amplification and sequence analysis of the 5′CS region of the integrons showed known antibiotic resistance-encoding gene cassettes of various sizes that were inserted within the respective integrons. Conjugation and transformation experiments indicated that some of the antibiotic resistance genes were likely plasmid-encoded and transmissible. All 47 isolates were subtyped by PFGE and PCR-based fingerprinting using random amplified polymorphic DNA (RAPD), repetitive extragenic palindromes (REPs), and enterobacterial repetitive intergenic consensus (ERIC). These isolates were very diverse and heterogeneous. PFGE, ERIC, and REP-PCR methods were more discriminative than RAPD in subtyping the E. coli isolates.

Highlights

Escherichia coli are one of the main bacterial pathogens responsible for nosocomial infections especially in immunocompromised patients [1]
All three PCR-based methods were reproducible as identical profiles were obtained in separate experiments using the same set of isolates
Similar observations were reported by Mugnaioli et al [24] and Woodford et al [16]

Summary

Introduction

Escherichia coli are one of the main bacterial pathogens responsible for nosocomial infections especially in immunocompromised patients [1]. Most ESBLs are mutants of TEM and SHV enzymes, the CTX-M type β-lactamases which have become important, originated from β-lactamases found in environmental species of the genus Kluyvera, and this enzyme hydrolyzes cefotaxime and cefriaxone but is weakly active against ceftazidime [3, 4]. These enzymes are present worldwide with more than 50 variants [4]. The widespread uses of antibiotics coupled with the transmissibility of resistance determinants mediated by plasmids, transposons, and gene cassettes in integrons are factors that contribute to the increase in antibiotic resistance in bacterial pathogens [1]

Objectives

Methods

Results

Conclusion