Objective: To determine the antibiotic susceptibility pattern of Enterobacteriaceae and incidence of extended-spectrum beta-lactamases-producing Enterobacteriaceae.

Methods: This descriptive study consisted of a sample size of 200 Enterobacteriaceae isolates, was conducted in the Microbiology section of the Pathology department of Nishtar Medical University Multan from November 2020 to November 2021. Blood, urine, and pus specimens were collected from patients of all age groups and either sex, after taking informed written consent. Identification was carried out by conventional biochemical tests and confirmed by Analytical Profile Index 20 E. Kirby-Bauer disc diffusion method was used to evaluate the sensitivity of bacterial isolates against different antibiotics. Identification of Extended Spectrum Beta Lactamase (ESBL) production was carried out by double-disc diffusion phenotypic confirmatory method.

Results: Among 200 culture-positive samples for Enterobacteriaceae, 77 (38.5%) were from pus samples, 51 (25.5%) were from blood and 72 (36.0%) were from urine samples. The highest frequency of 111 (55.5%) was identified as Eschercia coli. ESBL positive strains of enteric bacteria revealed in 29.5% of organisms. Patterns of drug susceptibility in ESBL negative showed highest resistance against Cefuroxime and Cefotaximeas 125/141 and 118/141 respectively while 59/59 for each in ESBL positive group.

Conclusion: A high proportion of ESBL-producing isolates belonging to Enterobacteriaceae were obtained from pus samples considering wound infections followed by urine and blood. The frequency of Eschercia coli remained the highest among ESBL and non-ESBL producer Enterobacteriaceae followed by Proteus and Enterobacter in this study. Meropenem and amikacin remained highly effective drugs for both groups followed by chloramphenicol and piperacillin/tazobactam.