Staphylococcus-induced gangrenous dermatitis in broilers

An infectious bursal disease (IBD)-vaccinated flock of 23,900 broilers, 17 days of age, experienced sudden onset of depression, dermatitis, and mortality. Postmortem examination showed extensive subcutaneous serosanguineous fluid accumulation over the pectoral muscles, discrete hepatic whitish foci, fluid-filled intestines, and small, flaccid bursae of Fabricius. Gram-stained impression smears from the affected areas revealed numerous gram-positive cocci. Aerobic culture of liver and subcutaneous tissue consistently produced heavy growth of penicillin-sensitive Staphyloccus aureus. Histopathologically, subcutaneous tissue showed diffuse hemorrhage and large numbers of gram-positive cocci with severe congestion and hemorrhage of the underlying skeletal muscle. Liver sections showed multiple, randomly scattered areas of acute coagulation necrosis with numerous gram-positive cocci. Bursal lesions were characterized by extensive follicular necrosis and collapse. A diagnosis of staphylococcal gangrenous dermatitis secondary to IBD was made. Mortality returned to preinfection levels within 72 hours after penicillin was added to the drinking water.