Focal dermatitis and cellulitis in broiler chickens: bacteriological and pathological findings

Involvement of aerobic bacteria, especially Escherichia coli, in lesions of cellulitis in broiler chickens was investigated. Samples of subcutaneous caseous material for bacteriological examination were collected aseptically at the slaughterhouse from 109 broilers with lesions. Skin tissue was taken from five of these birds for histopathological examination. In 96 of the 109 (88.1%) broilers sampled, E. coli was isolated from the lesion, and in 60 of these birds it was the only bacterial species found. In 33 broilers, Streptococcus dysgalactiae was found along with E. coli. Although serotype O78 was isolated the most frequently, numerous other serotypes were found; no correlation could be established between the size of the lesions and the serotype isolated. The microscopic lesions were characterized by thickening of the dermis with a granulomatous inflammatory reaction. This study confirms the frequent association of E. coli with cellulitis lesions in broiler chickens and reports the frequent isolation of S. dysgalactiae from the lesion.