EXTENDED SPECTRUM B-LACTAMASE PRODUCTION AMONGST GRAM NEGATIVE BACILLI ISOLATED FROM PATIENTS ATTENDING A TERTIARY CARE HOSPITAL IN EASTERN BIHAR

BACKGROUND: Extended Spectrum beta-lactamases (ESBL) are enzymes that have the ability to hydrolyze beta-lactam antibiotics containing oxyimino group and are inhibited by beta-lactamase inhibitors. These enzymes are responsible for resistance to penicillins, monobactams, third generation and in some instances fourth generation cephalosporins. ESBLs are encoded by transferable conjugative plasmids that often code for resistance to other antibiotics as well. OBJECTIVE: This prospective study aimed to determine ESBL production in Gram negative bacteria in patients attending a tertiary care hospital in eastern Bihar. METHOD: A total of 556 samples from patients attending inpatient and outpatient departments from May 2009 to April 2010 were included in the study. Samples were processed as per standard protocol and antibiotic susceptibility testing was done by modified Kirby-Bauer method. Isolates showing resistance to any third generation cephalosporin were subjected to Double Disc Synergy Test (DDST), Phenotypic Confirmatory Disc Diffusion Test (PCDDT) and MIC reduction test for ESBL production. RESULTS: 42.62% of Gram negative bacilli were ESBL producers. 56.3% of Klebsiella pneumoniae strains were found to be ESBL producers whereas only 40.5% of Escherichia coli produced ESBL. PCDDT and MIC reduction test showed 100% correlation whereas the DDST failed to detect 13.5% of ESBL producers. All ESBL producers were sensitive to Imipenem and Cefoperazone/ Sulbactam. CONCLUSION: The present study gives us an indication regarding the occurrence of ESBL producing Gram negative bacilli in Eastern Bihar. The number of ESBL producers in this region is alarmingly large. It is therefore recommended that PCDDT be incorporated in all laboratories as a part of routine antibiotic susceptibility testing procedures as it is simple, reliable and reproducible test for detection of ESBLs.