The present study was undertaken to isolate and determine the antibiotic sensitivity of E. coli, from drinking water samples collected from different sources in and around Ranchi, Jharkhand, India. The coliform count was done using most probable number (MPN). Isolation and identification of E. coli were done by morphological characteristics, enrichment media, selective media, and biochemical tests. Antimicrobial sensitivity testing by the disc diffusion method was conducted for 11 antibiotics: Amikacin, Amoxycillin, Ampicillin, Cephalothin, Chloramphenicol, Ciprofloxacin, Colistin, Cotrimoxazole, Enrofloxacin, Nalidixic acid and Oxytetracycline against isolated E.coli. The mean values of coliform MPN/100ml of water ranged from 0 to 1800+. Estimation of coliform in drinking water revealed that of 100 samples examined 47% samples had no coliform count, while in 6% samples the coliform count ranged between 1 to 10, in 7% samples the coliform count ranged between 11 to 20, in 19% the coliform count ranged between 21 to 100 and in 21% samples the coliform count was above 100 coliform per 100 ml of water. The isolates were highly sensitive to drug such as Amikacin (96.1%) and Colistin (96.1%) followed by Ciprofloxacin (92.3%), Chloramphenicol (88.4%) and Cotrimoxazole (84.6%). Intermediate sensitivity was shown for drugs such as Cephalolthin (34.6 %), Oxytetracycline (26.9 %) and Nalidixic acid (15.3 %). Maximum resistant was shown for drugs such as Enrofloxacin (73%), Oxytetracycline (65.3 %) and Cephalolthin (26.9 %). Although most strains of E. coli are not pathogenic, their presence is indicative of the possible presence of pathogenic organisms and the antibiotic sensitivity testing proved that the isolated E.coli are sensitive to many antibiotics and resistant to few of them.
Antibiotic sensitivity Test, Coliform count, E.coli, Water
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