Objective: Extended spectrum beta-lactamase (ESBL) mediated antibiotic resistance is a common problem among the causative agents of nosocomial infections both in terms of treatment failure and nosocomial spread. In this study, we investigated the presence of ESBL enzymes in Klebsiella pneumoniae and Escherichia coli strains isolated in Microbiology Laboratory of Kocaeli University Medical School.

Materials and Methods: The antibiotic susceptibilities of the isolates were determined by the disc diffusion method and the presence of the ESBL enzymes was investigated by double disc synergy test. Isoelectric focusing was performed for ESBL positive eight E. coli and eight K. pneumoniae isolates which were susceptible to ceftazidime and resistant to cefotaxime. Transconjugation experiments were performed between these eight positive isolates and the recipient E. coli J-53-2.

Results: ESBL positivity was detected in 52 (26.1 %) out of 199 E. coli and 33 (29.7 %) out of 111 K. pneumoniae isolates. The presence of ESBLs was confirmed by isoelectric focusing. Enzyme bands consistent with CTX-M type beta-lactamases were determined in isoelectric focusing in seven E. coli and six K. pneumoniae isolates. Plasmid isolations done in these transconjugates revealed presence of different kinds of plasmids.

Conclusion: Since the treatment of infections due to ESBL positive bacteria is costly and problematic, the surveillance of ESBL positive bacteria is of critical importance in the nosocomial setting.