Clostridium difficile Enteritis in Pigs
C difficile is an important emerging pathogen that causes diarrhea primarily in neonatal swine. The agent was first recognized as a cause of antibiotic-associated diarrhea in people. It most commonly causes disease in piglets 1–7 days old and in other domestic and laboratory animals.
C difficile is an anaerobic, gram-positive, sporeforming rod that is more oxygen-sensitive than C perfringens. The organism can be demonstrated in the intestine by direct Gram stain of smears. Survival of C difficile in the environment and shedding by carrier sows is believed to be important in transmission. C difficile produces “large clostridial toxins” A and B, which are thought to be involved in lesion production. Toxin A is an enterotoxin that causes fluid secretion into the gut lumen, and toxin B is a cytotoxin.
Affected piglets may have dyspnea, abdominal distention, and scrotal edema. Diarrhea may not be present in all pigs affected.
Gross lesions are not pathognomonic, and diagnosis must be confirmed by culture or demonstration of either toxin A or B and histopathology. C difficile can be cultured on selective media containing cefoxitin, cycloserine, taurocholate, and fructose under anaerobic conditions. The genes of toxins A and B are identified readily by PCR. The toxins can also be detected directly in suspensions of intestinal contents by commercially available enzyme immunoassays.
Based on minimum inhibitory concentration determinations, it has been suggested that erythromycin, tetracycline, and tylosin may be useful for treatment of suckling piglets, and tiamulin and virginiamycin may help to reduce levels of the organism in adult swine. No controlled studies on the effect of antibiotics on clinical disease have been reported.