1College of Veterinary Science
2Department of Microbiology and Immunology, Pt. Deen Dayal Upadhayaya Veterinary University and Gau-Anusandhan Sansthan, Mathura, 281 001, (Uttar Pradesh)
*Corresponding Author: E-mail: abharadwaj@scientist.com
(Present Address): Department of Veterinary Microbiology, CCS Haryana Agricultural University, Hisar, 125001, (Haryana), INDIA
One hundred and sixteen Escherichia coli strains, belonging to 35 serogroups of diarrhoeic and non-diarrhoeic bovine neonates faeces revealed that 11(9.4%) E. coli strains showed complete haemolysis on spot inoculation and 8(6.8%) showed partial hemolytic zone of haemolysis and rest were negative on cattle, horse, rabbit and sheep blood agar plates. E. coli strains of serogroups O4 (1), O26 (4), O68 (1), O109 (1), O111 (1), O117 (1) and O119 (2) showed complete zone of haemolysis while E. coli strains of serogroups O1 (1), O2 (1), O8 (1), O107 (1), O143 (1) and O156 (3) were partially haemolytic. The haemolysins purified from E. coli strains of serogroups O4, O26 (4), O119 tested against rabbit, sheep, cattle, horse erythrocytes in fluid, revealed varying degree of haemolysis. Only 5 E. coli strains of O26 serogroup were positive for Ehly and harboured VT2 gene, rest of the haemolytic isolates were negative. However extracted haemolysin dialysates of haemolytic E. coli strains and cell free cultural supernatants belonging to various serogroups produced haemorrhagic enteritis, tested by rabbit ligated ileal loop.
EHEC, Escherichia coli, E-hly, VT2, enterohemolysin
