Investigation of Extended Spectrum Beta-Lactamase (ESBL) Genes in ESBL-Producing Escherichia coli and Klebsiella pneumoniae Strains

Introduction: Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is an important health problem all over the world. In this study, it was aimed to determine the ESBL genes in Escherichia coli and Klebsiella pneumoniae strains isolated for approximately four-year period. Materials and Methods: A total 100 ESBL-producing E. coli and 100 ESBL-producing K. pneumoniae strains which were isolated between January 2008 and October 2012 were included into this study. The strains were identified using classical bacteriologic methods and BD Phoenix (Becton Dickinson, US) automatized bacterial identification device. CTX-M, TEM, SHV, VEB, GES, PER and OXA beta-lactamase genes were analyzed with the PCR method. Results: The beta-lactamase genes detected in ESBL-positive K. pneumoniae strains were as follows: 99% for CTX-M, 91% for SHV, 71% for TEM, 10% for OXA-10 group, and 5% for OXA-2 group. In E. coli strains, the prevalence of CTX-M was 92%; TEM was 70%, SHV was 21%, and OXA-2 group was 3%. CTX-M alone was found to be positive in 25 of the 98 (25.5%) in E. coli strains; TEM alone was found to be positive in 2 of 98 (2%) and SHV alone was found in 2 of 98 (2%). CTX-M alone was found positive in 3 of 100 (3%) K. pneumoniae strains. No other resistance genes alone were found in the strains. No GES, VEB and PER-producing strains were determined in this study. Conclusion: In the study, high prevalence of CTX-M beta-lactamase was found in ESBL-producing strains. It was thought that the high potential of mobility with CTX-M genes was the most possible reason for this result. Determination of ESBL genes will be useful to understand resistance epidemiology, develop effective therapeutic strategies, and plan the appropriate preventive measurements