Concomitance of cytotoxigenic and non-cytotoxigenic Clostridium difficile in stool specimens.

Six patients with antibiotic-associated diarrhea and one patient with diarrhea unrelated to antibiotic use yielded both cytotoxigenic and non-cytotoxigenic isolates of Clostridium difficile from the same stool specimens. In addition, these isolates were shown to be pathogenic and nonpathogenic, respectively, in the hamster model of antibiotic-associated colitis. These data imply that more than one toxin type of C. difficile may be harbored simultaneously. If toxin testing is used to identify C. difficile, more than one colony must be tested.