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Enterotoxemia Caused by Clostridium perfringens Type A |  |
| Type A strains of
C
perfringens
are commonly found as part of the normal intestinal microflora of animals and lack some of the powerful toxins produced by strains of other types. Nonetheless, they produce the lethal and necrotizing α toxin and are incriminated in necrotic enteritis in poultry (
Necrotic Enteritis: Introduction) and dogs, in colitis in horses, and in diarrhea in pigs.
C
perfringens
type A is clearly implicated in a rarely occurring hemorrhagic diarrhea in dogs. The disease is characterized by a necrotic enteritis in which there is massive destruction of the villi and coagulation necrosis of the small intestine. These organisms are also associated with chronic intermittent diarrhea in dogs but have not been confirmed as the causal agent. Typically, large numbers of large, gram-positive rods are visible in fecal smears, and large numbers of
C
perfringens
type A are recovered on anaerobic culture of feces. Other known enteric pathogens are usually absent. Untyped
C
perfringens
has also been shown to proliferate in the intestines of dogs with parvoviral enteritis, but its contribution to disease is not clear. Production of enterotoxin by type A strains of
C
perfringens
can induce diarrhea in humans, but this has not been demonstrated in dogs. Type A strains from pigs with diarrhea have produced enterotoxin in vitro, and anti-enterotoxin antibodies in sows indicate that enterotoxin is produced in vivo in pigs. Enterotoxin has also been demonstrated in the feces of pigs with diarrhea but not in feces of healthy pigs. However, recent studies have shown that
C
perfringens
isolated from pigs with diarrhea are typically nonenterotoxigenic but produce the cytotoxic β2 toxin, which has been suggested to play a role in disease. Experimental disease has been produced in pigs challenged orally with
C
perfringens
type A. |
