The influence of Escherichia coli strains from different sources and the age of broiler chickens on the development of cellulitis

In two experiments, broilers were challenged with one of several field stra ins of Escherichia coli to determine whether the source of the E. coli and age of the bird at time of inoculation affected the development of cellulit is lesions. In the first experiment, birds inoculated at 52 days of age wit h E. coli of faecal, airsacculitis and cellulitis origin exhibited a cellul itis lesion incidence of 47.5, 25 and 77.5%, respectively. This study confi rms earlier observations that E. coli strains isolated from cellulitis lesi ons express a higher propensity for producing these same lesions than other strains, including those associated with airsacculitis. In the second expe riment, birds were inoculated at 4, 7, 10, 16, 28, and 52 days of age with an E. coli strain of cellulitis origin and necropsied 2 days post-infection . The resulting incidence of cellulitis ranged from 20% (day 7) to 95% (day s 16 and 28), indicating that cellulitis can develop in any age of bird, al though the lesions were frequently associated with other manifestations of colibacillosis (perihepatitis, pericarditis, airsacculitis) in birds challe nged from 4 to 16 days of age.