Antibiotic Resistance and Plasmid Profiling of Esherichia Coli Isolates of Drinking Water

Abstract

E. coli has a central role in water microbiology due to its indicator value of faecal pollution. Antibiotic resistance and its dissemination in water is a serious public health issue. The objective of the study was to explore the occurrence and distribution of E. coli in drinking water, their susceptibility to antibiotics and plasmid profiling. This study was conducted at Laboratory of Central Department of Microbiology, from January to August 2011. A total of 66 water samples from tap, well and spring sources were bacteriological parameters. Disc diffusion was followed for antibiogram and plasmid DNA of thermotolerent E. coli was extracted by mini alkaline lysis following gel electrophoresis. Type of water sources were not significantly associated with the presence of coliform (P=0.155) and thermotolerant coliform (P=0.235) and the significant association in thermotolerant coliform and thermotolerant E. coli was found for all sources tap (P=0.029), well (P=0.028), spring (P=0.05) but total coliform and E. coli association was found for well (P=0.01). Average count of thermotolerant E. coli was found higher than E. coli in all sources. All E. coli were found sensitive towards Ofloxacin, Chromphenicol and Cotrimixazole. Resistance to Cefexime, Amikacin and Nalidixic acid, Amoxicillin, Tetracycline were 54.8%, 29% 35.5%, 80.6%, 93.5% and 57.6%, 36.4%, 39.4%, 94%, 100% was observed in E. coli and thermotolerant E. coli respectively. High MDR 25 (75.8%) of thermotolerant E. coli was observed than E. coli 22 (70.9%). In gel electrophoresis, single band of plasmid were observed in three MDR isolates and one non-MDR isolate and size varied from 2kb to >10kb. All NAR thermotolerant E. coli were found to harbor plasmid. Drinking water of Kathmandu is contaminated with drug resistance E. coli and plasmid mediated resistance to Nalidixic acid has emerged indicating possible outbreak of drug resistance enteric bacteria.