Wide diversity of Clostridium difficile types at a tertiary referral hospital.

Nosocomial Clostridium difficile infection was investigated at a hospital with 15 cases of C. difficile diarrhea per 1000 discharges. From January 1991 to May 1991, patients admitted or transferred to five wards or units had weekly rectal swabs taken for culture; in addition, all cytotoxin-positive stools were cultured. Restriction enzyme analysis (REA) was used for molecular typing. Among 205 isolates from 39 patients with C. difficile diarrhea and 67 asymptomatically colonized, 55 distinct REA banding patterns were identified. Evidence for patient-to-patient transmission was limited, in that numerous strains were found even among clustered cases of diarrhea. Patients who acquired C. difficile in the community or other hospitals constituted 32% of culture-positive patients and contributed 44% of the REA types. Diversity of C. difficile strains was in part the result of patients acquiring C. difficile in the community or other hospitals. High incidences of nosocomial C. difficile diarrhea do not necessarily indicate clonal epidemics.