Virulence factors of Escherichia coli isolated from Colisepticemia of poultry

An outbreak of Foot and Mouth Disease was investigated in a herd of 500 cows in The present work was carried out to study prevalence of various virulence factors among Escherichia coli (E. coli) isolated from respiratory system of chicken affected with coli septicemia. A total of 473 samples were collected from live and dead poultry birds and E. coli was isolated from 206 (43.6%) samples. Out of these, 162 could be serotyped which can be grouped under 50 different serotypes. Serotypes O81, O1, O78, O8, O88 and O136 were among the major pathogenic serotypes. Out of 74 isolates studied, only 9 (13.2%) were able to produce haemolysin. Invasiveness was determined with Congo red dye binding test and Sereny test and 47 (63.57%) isolates were positive for Congo red dye binding though no isolate was found positive for Sereny test. Along with that ten isolates could elaborate toxins and among them 6 (13.6%) were positive for heat stable toxin (ST) and 4 (12.9%) for heat labile toxin (LT).