DOI: 10.36347/sjams.2017.v05i10.044

Pages: 4030-4036

The present study was undertaken to evaluate the prevalence of the extended spectrum β- lactamase (ESBL) producing gram negative strains at our tertiary care hospital by using the Modified Double Disc Synergy Test (MDDST) and CLSI phenotypic confirmatory test (PCT). A total of 300 non-repetitive isolates of enterobacteriaceae from various clinical samples of urine, blood, pus, wound swab, sputum, or intravenous catheter were obtained from inpatient units of various wards of our tertiary care teaching hospital. Gram negative isolates having zone size of <=22mm for ceftazidime and <=27mm for cefotaxime (standard disc diffusion method) were selected as suspicious for ESBL production as recommended by CLSI guidelines. These potential ESBL producing strains were further tested by MDDST and CLSI PCT methods. Among the 300 clinical isolates tested 154 gram-negative isolates were considered suspicious of ESBL production by the initial screening test for ESBL production by the initial screening method. Out of these 154 isolates 148(49.33%) were confirmed to be ESBL producer by phenotypic confirmatory tests. Amongst the various bacterial isolates tested positive for ESBL production maximum percentage of ESBL producer were Klebsiella spp. (67.08%) followed by Pseudomonas spp. (60%), Acinetobacter spp. (54.16%), Proteus spp. (40%), Escherichia coli (33.63%) and Citrobacter spp. (30.78%). Majority of ESBL producing strains were from surgery wards (27.02%) followed by ICUs (22.29%), medicine wards (19.59%). Minimum percentage of ESBL producers were from paediatric wards (5.40%). Both the MDDST and PCDDT methods were highly sensitive and specific in detection of ESBL production. PCDDT was more sensitive in detecting ESBL production in Klebsiella spp., Pseudomonas spp. and Acinetobacter spp. but the difference is not statistically significant.