Antibiotic Resistance of E. coli Isolated from the Faecal Samples of Calf Diarrhoea

Antibiotic resistance of E.coli is one of the major challenges being faced in the treatment of calves suffering with colibacillosis. E. coli can acquire high level of resistant to some of the antibiotics either by spontaneous genetic mutation or by transfer of drug resistant plasmid to the recipient cells. This generally occurs due to indiscriminate use of antibiotics as chemotherapeutic agent or feed additives. In present investigation, total 86 E. coli strains isolated from the faecal samples of the bovine calves up to 4 months of age were subjected to antibiotic sensitivity test by disc diffusion method as per technique of Bauer et al. (1966) against the commonly used antibiotics for the treatment of calf diarrhoea.The antibiotic sensitivity pattern of E.coli isolated from the faecal samples of the diarrhoeic calves showed 100.00% sensitivity to ofloxacin, norfloxacin and chloramphenicol followed by ciprofloxacin and nalidixic acid (98.84% each), kanamycin (94.19%), enrofloxacin (90.70%), gentamicin (81.39%), doxycycline (79.07%), streptomycin (65.12%), trimethoprim (58.14%), sulphadimidine (48.84%), cotrimoxazole (46.51%), oxytetracycline (41.86%), tetracycline (38.37%) and erythromycin (6.98%). The E. coli isolates showed maximum resistance against erythromycin (93.02%), followed by tetracycline (40.70%), oxytetracycline (34.88%), sulphadimidine (33.72%), streptomycin (32.56%), cotrimoxazole (30.23%), trimethoprim (20.93%), doxycycline (9.30%), enrofloxacin (6.98%) and ciprofloxacin (1.16%). It was concluded that E.coli was highly sensitivity to ofloxacin, norfloxacin, chloramphenicol, ciprofloxacin, nalidixic acid, enrofloxacin and gentamicin. This might be attributed to the fact that these antibiotics were seldom used in treatment of enteric infections in bovine calves. Out of 86 E. coli isolates, 30 (34.88%) showed multiple antibiotic resistance for 3 to 8 antibiotics. Multiple resistant pattern is possibly due to indiscriminate use of antibiotic therapy which exerts a selection pressure and leads to the development of multiple drug resistance among different strains of bacteria.