The frequency of TEM and SHV beta-lactamases in Escherichia coli and Klebsiella pneumoniae strains

Abstract

The aim of this study was to determine the frequency of TEM and SHV genes and the ratio of extended spectrum beta-lactamases (ESBLs) in 85 Escherichia coli and 83 Klebsiella pneumoniae strains which were isolated from clinical specimens of patients with nosocomial infections, TEM and SHV genes have been searched by polymerase chain reaction (PCR), putative ESBL production were determined by double disk synergy test and antibiotic susceptibilities of the isolates were investigated with standard disk diffusion method. Of a total of 168 bacterial isolates, 150 (89.3%) were found to have genes encoding TEM or SHV type beta-lactamases. TEM type beta-lactamases were determined in 78.8% of E. coli and 69.9% of K.pneumoniae strains, and the of bla SHV were 47.1% and 59%, respectively. 38.1% of the isolates positivity rates had both bla TEM and bla SHV. 12.9% of E. coli strains and 32.5 % of K.pneumoniae strains were putative ESBL producers. The resistance rates of E. coli and K.pneumoniae to ampicillin, amoxicillin/clavulanic acid, aztreonam, ceftazidime, cefotaxime and cefoxitin were detected as 77.6% and 88%, 44.7% and 54.2%, 20% and 44.6%, 18.8% and 41%, 14.1% and 38.6%, and 16.5% and 30,1% respectively. All strains were found to be susceptible to imipenem and meropenem. In conclusion, the TEM-SHV beta-lactamases gene positivity rates of E. coli and K. pneumoniae strains were found to be high and putative ESBL production was higher in K. pneumoniae than E. coli isolates.