Detection of Extended-Spectrum Β-Lactamases among Gram Negative Isolates from Gombe Specialist Hospital Using Disc Replacement Method

Abstract

A total of 500 clinical bacterial isolates from various sources including stool, urine, sputum and swabs obtained from Gombe State Specialist Hospital between July, 2011 and January, 2012 were used in this study. Gram’s stain reaction of the isolates separated them into Gram-positives (200) and Gram-negatives (300). Biochemical tests confirmed the identity of the Gram-negative isolates to be members of the enterobactericeae, which included Klebsiella pneumoniae (60), Escherichia coli (98), Providencia Spp. (32), Morganella moganii (32), Shigella Spp. (14), Citrobacter freundii (14), Serratia marcescens (10), Salmonella paratyphi A (10), Yersinia enterocolitica (8), Proteus vulgaris (4), Salmonella typhi (2) and Pseudomonas aeruginosa (16). Of the 300 Gram-negative isolates subjected to screening using Cefpodoxime (CPX 10μg, oxoid England) and Cefotaxime (CTX 30μg, Oxoid England) for ESβL- production based on Clinical Laboratory Standard Institute (CLSI) breakpoint, 250 (83.33%) were found to be positive which included K. pneumoniae (40), E. coli (92), Providencia Spp. (30), M. morganii (20), P. aeruginosa (14), Shigella Spp. (14), C. freundii (12), S. marcescens (6), and Y. enterocolitica (6), S. paratyphi A (10), P. vulgaris (4) and S. typhi (2). However, one hundred and sixty four, 164 (65.6%) were confirmed ESβL- producers based on DRM using Amoxicillin-clavulanate (AMC 30μg, Oxoid England) which included; K. pneumoniae 32(19.50%), E. coli 52(31.71%), Providencia Spp 20(12.20%), M. morganii 16(9.76%), P. aeruginosa 8(4.88%), Shigella Spp. 12(7.32%), C. freundii 6(3.66%), S. marcescens 4(2.44%), S. paratyphi A 8(4.88%), Y. enterocolitica 6(3.66%), P. vulgaris (0.0%), and S. typhi (0.0%).

Keywords: Detection, ESBLs, Clinical isolates, Disc Replacement Method, Gombe