Study of virulence factors of Escherichia coli strains isolated from diarrhoeic calves Udaykar Aniruddha1, Sharda Rakesh*, Chhabra Daljeet, Sharma Varsha Department of Microbiology, College of Veterinary Science and Animal Husbandry, Mhow - 453 556 (M.P.) *Corresponding author: e.mail - swaraksha@yahoo.com
1Assistant Professor, Deptt. of Microbiology, Mahatma Gandhi Veterinary College, Bharatpur (Raj), India. Abstract Sixty two E. coli isolates belonging to different serotypes, recovered from diarrhoeic cow and buffalo calves, were studied for virulence factors, such as adhesins, invasins, colonization factor and haemolysin and enterotoxin production, by using a battery of in vitro and in vivo tests. Eight (12.9%) isolates were haemolytic on trypticase soya agar (TSA) containing 5% sheep blood. Thirty six (58.06%) isolates showed binding of Congo Red (CR) dye and produced brick red colonies on TSA-CR medium. Thirty (48.38%) isolates were positive for salt aggregation test producing clumped mass with different molar solutions of ammonium sulphate prepared in 0.02 M sodium phosphate solution. The E. coli serotypes O2, O3, O13, O20, O22, O69, O88, O98, O108, O110, O138, and O171 and untypable strains isolated during present study produced LT enterotoxin as revealed by mouse paw oedema test. Top |