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 humans. It most commonly causes disease in piglets 1–7 days old and in other domestic and laboratory animals.
Etiology and Pathogenesis
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's 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.
Ascites, hydrothorax, and edema of the ascending colon have been reported. Urates are commonly present in the kidneys. Pasty to watery colonic contents may be observed. Microscopically, the colon is primarily affected with multifocal exudation of mucus and fibrin plus submucosal edema.
Gross lesions are not patho-gnomonic, and diagnosis must be confirmed by culture or demonstration of either toxin A or B and histopathology. C difficile can be cultured on selective medium 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.
Treatment and Control
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 be helpful in reducing levels of the organism in adult swine. No controlled studies on the effect of antibiotics on clinical disease have been reported.
Last full review/revision March 2012 by D. L. Hank Harris, DVM, PhD