Experimental studies of antibiotic associated colitis.

Clostridium difficile has been implicated as the major cause of antibiotic-associated pseudomembranous colitis. The laboratory diagnostic test of choice is a tissue culture assay that demonstrates the presence of a cytopathic toxin neutralized by antitoxin to Clostridium sordelli. This toxin is found in stools from patients with antibiotic-associated pseudomembranous colitis and in stools from patients with antibiotic-associated diarrhea. Neutralization of toxin by antitoxin to C. sordelli appears to represent antigenic cross-reactivity, since both cultures of C. difficile also contain a cytopathic toxin neutralized by this toxin. Strains of C. difficile are susceptible to vancomycin and the clinical experience with oral administration of this agent shows promising results.