Background: Aim of the study was to know the occurrence of ESBL, AmpC and carbapenemases producers among Enterobacteriaeceae by phenotypic disc diffusion tests. Materials and methods: A total of 209 isolates belonging to the family Enterobacteriaceae obtained from different clinical samples received in the Department of Microbiology, AIMS. B.G. Ngara were included in the study. ESBL screening was done, followed by phenotypic confirmatory test by CLSI recommended combination disc method. AmpC screening and confirmation was done by phenylboronic acid test and AmpC disc test. Carbapenemase producers were screened and confirmed by CLSI recommended MHT and Remodified Hodge test for KPC detection and double disc synergy test, EDTA disc potentiation test for MBL detection. Results: The most common organism isolated was Escherichia coli 101 (48.31%) followed by Klebsiella species 52 (27.27%). Of the 209 isolates of Enterobacteriaceae 24.88%, 1.91% and 7.17% were pure ESBL, AmpC and carbapenemase producers respectively. 5.7% were ESBL and AmpC co-producers, 11.96% were ESBL and carbapenemase co-producers, 2.39% were AmpC and carbapenemase co-producers and 6.22% were combined ESBL, AmpC and carbapenemase co-producers. Conclusion: Cefotaxime/clavulanate disc potentiation test detected maximum number of ESBL producers compared to Ceftazidime/ Clavulunate. Cefoxitin–boronic acid detected maximum number of AmpC producers compared to AmpC disc test. Remodified Hodge test is better than MHT in detecting KPC producers. DDST detected more number of MBL producers compared to EDTA disc potentiation test and is a satisfactory and inexpensive method for characterizing the type of carbapenemase producers, when genotypic methods are not available.

Keywords: ESBL; AmpC; Carbapenemases; Phenotypic Methods