Department of Microbiology M.P.P.C.V.V., College of Veterinary Science and Animal Husbandry, Mhow, (Madhya Pradesh)
* Corresponding author: Assistant Professor, Deptt. of Microbiology, Veterinary College, Chomu (Raj).
Twenty seven isolates of Escherichia coli recovered from diarrhoea in buffalo calves were tested for virulence factors by a battery of in vivo (pathogenicity and enterotoxigenicity) and in vitro methods. Out of 27 isolates, 11 (40.74%) proved fatal to Swiss albino mice on intraperitoneal inoculation of whole bacterial culture. Similarly the cell free filtrate (crude toxin) of 5 (18.51%) isolates, belonging to O22, O60, O88, O110 and O127 serogroup caused death of mice within 6 hpi. None of the isolates produced STa or LT enterotoxins in suckling mouse and mouse paw oedema test, respectively. Four (14.81%) isolates were found resistant towards the lytic action of bubaline calf serum, whereas 7 (25.92%) were sensitive to serum; remaining 16 (59.25%) isolates were intermediate sensitive. The in vitro sensitivity of the isolates to antimicrobial drugs was 100% for ceftriaxone and ceftriaxone/tazobactum, followed by ciprofloxacin (92.60%), sulfadiazine (88.89%), cefotaxim (66.67%), amoxyclav (62.97%), and amikacin (22.23%).
