Background: Extended spectrum beta-lactamases (ESBLs) represent a major group of of β-lactamases currently being identified worldwide in large numbers, most commonly produced by Klebsiella pneumoniae and Escherichia coli but also occur in other gram negative bacteria. The most common cause of bacterial resistance to β-lactam antibiotics is the production of β-lactamase enzymes.

Objective: To determine the prevalence and antibiotic susceptibility pattern of ESBL producers among Escherichia coli and Klebsiella pneumoniae isolates.

Material and Methods: A total of 400 clinical isolates, 203 Escherichia coli and 197 Klebsiella pneumoniae were isolated from various clinical specimens and tested for ESBL production. Screening and confirmatory tests for ESBL production were done according to Clinical Laboratory Standard Institute’s guidelines.

Results: Out of 400 isolates of Escherichia coli and Klebsiella pneumoniae, 197 (49.25 %) were found ESBLs producers. Out of 203 Escherichia coli isolates 92 (45.32 %) were found ESBLs producers and of the 197 Klebsiella pneumoniae isolates 97 (49.23%) were found ESBLs producers. ESBL producing E. coli and K. pneumoniae strains were most frequently recovered from urine 42.39% and pus 43.29% respectively. ESBL producing both E. coli and K. pneumoniae strains were most sensitive to imipenem followed by gentamycin.

Conclusion: Routine detection of ESBL-producing microorganisms is required to be done by each laboratory by the standard detection methods so as to control the spread of these infections.