Molecular characterization of extended-spectrum beta-lactamase producing Enterobacteriaceae in a Saudi Arabian tertiary hospital

Hoda Hassan,Baha Abdalhamid

doi:10.3855/jidc.3809

Abstract

The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. mirabilis). In addition, different methods for detection of these enzymes, including the newly introduced CHROMagar ESBL, were evaluated. A total of 382 Enterobacteriaceae clinical isolates were obtained from King Fahad Specialist Hospital - Dammam, during 2011 and screened for production of ESBL using advanced expert system of Vitek 2, CHROMagar and ESBL-E-strips. PCR assay was used to detect blaTEM, blaSHV, and blaCTX-M genes. Susceptibility to a panel of antibiotics was determined. The overall proportion of ESBL-producing enterobacterial isolates was 30.6%, which was higher in E. coli (35.8%) than in K. pneumoniae (25.7%). ESBL genotypes showed remarkable increase in the CTX-M (97.4%) compared to SHV (23.1%). The predominant ESBL was CTX-M- 15 (92.1 %). No TEM ESBL was detected in this study. The Vitek2 showed the highest sensitivity (100%), and the CHROMagar had the lowest specificity (97.3%) compared to the molecular method. All isolates were susceptible to imipenem and meropenem. This study confirms a high level of blaCTX-M positive ESBL isolates are circulating in the Eastern Province of Saudi Arabia. The trend of a multidrug-resistant profile associated with the recovery of the blaCTX-M gene is alarming.

Highlights

The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. mirabilis)
DNA sequence analysis showed that all amplicons obtained for the CTX-M-1 group were characterized as CTX-M-15, and all amplicons obtained for the CTXM-9 group were characterized as CTX-M-14
The proportion of ESBL producers was higher in E. coli (35.8%) than in K. pneumoniae (25.2%)

Summary

Introduction

The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. mirabilis). Different methods for detection of these enzymes, including the newly introduced CHROMagar ESBL, were evaluated. Conclusions: This study confirms a high level of blaCTX-M positive ESBL isolates are circulating in the Eastern Province of Saudi Arabia. Microbial resistance through extended-spectrum beta-lactamase (ESBL) was first reported in the early 1980s in Europe and subsequently in the United States soon after the introduction of third-generation cephalosporins in clinical practice [1]. The dominant enzyme variants until the late 1990s were TEM, SHV, and OXA, while CTX-M ESBLs were rarely recorded [1,2]. A faster and more reliable detection method is desirable, as the determination of antibiotic susceptibility is crucial for positive antimicrobial therapy outcomes and significantly influences subsequent procedures and actions [10]

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