The association of various isolates of Escherichia coli from the United States with induced cellulitis and colibacillosis in young broiler chickens

An experiment was conducted to observe the effects of 10 different avian Es cherichia coli isolates in 3-day post-hatch broiler chicks after subcutaneo us administration. Isolates were originally obtained from various avian sou rces throughout the US. Chicks were injected subcutaneously on the ventral surface and necropsied at 7-day intervals for 3 weeks. Cellulitis was produ ced in all treatments receiving E. coli of cellulitis origin, with the high est incidence occurring 2 weeks post-infection in birds that received an is olate recovered in a previous challenge experiment. Cellulitis was also obs erved at week 1 post-infection in a small percentage of the birds in two of the treatments receiving E. coli of enteric origin, although lesions disap peared from the group after week 1 post-infection. Septicaemia was the most frequent sequel to challenge and occurred regardless of which isolate was injected. Chicks exposed to cellulitis origin isolates developed septicaemi a more frequently than birds challenged with E. coli of non-cellulitis orig in. The data implies that cellulitis is unlikely to occur early in the bird 's life, since young birds exposed to E. coli frequently develop septicaemi a.