Extended spectrum beta-lactamase producing Escherichia coli and Klebsiella pneumoniae isolated in a rural hospital.

Extended spectrum beta-lactamase (ESBL) producing strains pose greatest therapeutic challenge and have been reported as emerging pathogens causing nosocomial infection. The present study was undertaken to detect the ESBL producing Esch coli and Klebsiella pneumoniae strains, which were screened to detect ESBL production. A total number of 320 E. coli and Klebsiella pneumoniae strains were processed in the microbiology department. Antibiotic sensitivity test with ciprofloxacin, amikacin, cefotaxime, ceftazidime, imipenem, etc, was put by Kirby Bauer method. ESBL producing strains were detected by double disc synergy test (DDST) using cefotaxime (30 microg) and amoxicillin/clavulanic acid (20/10 microg) disc. ESBL production was confirmed by minimum inhibitory concentration (MIC) reduction test in presence of clavulanic acid and fractional inhibitory concentration (FIC) index. MIC of cefotaxime was done by broth dilution technique. One hundred and thirty-seven strains (42.8%) were ESBL positive; 41.3% E. coli and 44.7% Klebsiella pneumoniae were ESBL producers; One E. coli strain and 4 Klebsiella pneumoniae strains had MIC of cefotaxime 256 microg/ml. To conclude, DDST method for screening of ESBL producing strains is quite simple, cost effective and yet reliable test which can be adopted by any clinical microbiology laboratory.