Necrotic Enteritis in Chickens Associated with Clostridium sordellii

Three outbreaks of necrotic enteritis-like disease associated with Clostridium sordelii were diagnosed in commercial broiler chicken flocks with 18,000 to 31,000 birds between 18 and 26 days old. Clinical signs in the affected flocks included high mortality up to 2% a day, depression, and diarrhea. The main gross changes included segmental dilation of the small intestine with watery contents, gas, mucoid exudate, and roughened and uneven mucosa, occasionally covered with a pseudomembrane. Microscopic lesions in the small intestine were characterized by extensive areas of coagulative necrosis of the villi, fibrinous exudate in the lumen, and high numbers of large, Gram-positive rods, occasionally containing subterminal spores, seen in the necrotic tissue and lumen. These rods were identified as C. sordellii by immunohistochemistry. Clostridium sordellii was isolated in an almost pure culture from the intestine of affected birds. A retrospective study of commercial broiler chicken and turkey submissions to the California Animal Health and Food Safety Laboratory System revealed that C. sordellii had been isolated from intestinal lesions in outbreaks of necrotic enteritis-like disease in 8 of 39 cases, 5 times together with Clostridium perfringens and 3 times alone. The latter three cases are reported here.