We prospectively studied the comparative epidemiology and risk factors for Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus antibiotic-associated diarrhea (AAD). Four thousand six hundred fiftynine inpatient fecal specimens (11 months) were tested for C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus by Vero cell assay, enzyme-linked immunosorbent assay, and growth on fresh blood agar, respectively. Two distinct age-, sex-, and location-matched control patient groups were used for multivariate logistic regression risk factor analyses: symptomatic patients who were AAD pathogen negative and asymptomatic patients with histories of recent antimicrobial therapy. All AAD pathogen isolates were DNA fingerprinted. In AAD cases, the prevalences of C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus were 12.7%, 3.3%, and 0.2%, respectively (15.8% overall). Age of >70 years was a common risk factor. Other risk factors for infective AAD and C. difficile AAD included length of hospital stay and use of feeding tubes (length of stay odds ratios [OR], 1.017 and 1.012; feeding tube OR, 1.864 and 2.808). Female gender and use of antacids were significantly associated with increased risk of C. perfringens AAD (OR, 2.08 and 2.789, respectively), but unlike what was found for C. difficile AAD, specific antibiotic classes were not associated with increased risk. A limited number of genotypes caused the majority of C. difficile and C. perfringens AAD cases. Similar to what was found for C. difficile AAD, there was epidemiological evidence of C. perfringens AAD case clustering and reinfection due to different strains. C. difficile AAD was approximately 4 and 60 times more common than C. perfringens AAD and S. aureus AAD, respectively. Risk factors for these AAD pathogens differed, highlighting the need to define specific control measures. There is evidence of nosocomial transmission in cases of C. perfringens AAD.

Clostridium perfringens has been reported as the cause of up to 15% of cases of antibiotic-associated diarrhoea (AAD) and may be diagnosed by detection of enterotoxin (CPEnt) in faeces. The performance of a commercial ELISA method for CPEnt, with culture and PCR methods to confirm the presence of enterotoxigenic C. perfringens, was evaluated in 200 consecutive specimens from patients with clinical details suggestive of AAD: 8% of the specimens were positive for CPEnt, 16% were positive for C. difficile cytotoxin and 2% gave positive test results for both C. perfringens and C. difficile toxins. Culture and PCR results confirmed the majority of ELISA results, although 2 (12.5%) reactive specimens were only weakly positive. C. perfringens is a potentially important cause of infective AAD and can be detected with the C. perfringens enterotoxin ELISA kit, although weak positive results should be considered with caution.

We noted that some Clostridium difficile isolates are nonrecoverable after frozen storage and so used molecular typing analysis to characterize DNA from these strains. The recovery rate of C. difficile PCR ribotype 1 was statistically significantly greater than that of other strains. This observation has implications for C. difficile epidemiological studies.