Objective: The aim of this study is to evaluate ESBL production and CTX-M enzyme types in Escherichia coli and Klebsiella spp isolates obtained from patients admitted to our hospital.

Material and Method: A total of 593 isolates from various clinical specimens of patients between June 2009 and December 2009 were included in the study. Antibiotic susceptibility test was performed by Kirby-Bauer disk diffusion method. ESBL production was confirmed by double-disc synergy and E tests.The minimal inhibitory concentrations of cefotaxim for the isolates with ESBL were detected by agar dilution method. Polymerase chain reaction was used to determine the CTX-M enzyme types including CTX-M group, CTX-M-1 group, CTX-M-2 group, CTX-M-8 group, CTX-M-9 group, CTX-M-25 group, CTXM- 15, CTX-M-3, and CTX-M-10 types.

Results: ESBL production was found in 33.7% (200/593) of the isolates (34.3% for E. coli and 31.3% for Klebsiella isolates). ESBL production was significantly high in isolates from inpatients. Resistance to ciprofloxacin, levofloxacin, amoxicillin/clavulanic acid, piperacillin/tazobactam, gentamicin, amikacin, tobramycin, trimetoprimsulphametoxazol and nitrofurantoin was significantly higher in ESBL producing isolates. CTX-M enzymes were found in 192 (96%) of the 200 ESBL producing isolates. Of the CTX-M producing isolates, CTX-M-1, CTX-M-2, CTXM- 8 and CTX-M-9 groups were found in 96.8% (186/192), 5.2% (10/192), 1% (2/192) and 1.5% (3/192), respectively. CTX-M-15 was found in 165 of the 186 (88.7%) CTX-M-1 group ESBL producing isolates.

Conclusions: High rates of ESBL production was found among the isolates in our hospital. The most common enzyme type was CTX-M-1 group, CTX-M-15 being the most common enzyme type.