Nosocomial Clostridium difficile colonisation and disease.

To assess the risk of acquiring Clostridium difficile diarrhoea or colitis in patients colonised with C difficile, rectal swabs taken weekly for 9 weeks from patients with long-term (at least 7 days) hospital stays on three wards were cultured for C difficile. 60 (21%) of 282 patients were culture-positive for C difficile during their hospital stay, of whom 51 were symptom-free faecal excretors. C difficile diarrhoea developed in the other 9 patients; 2 were culture-positive for C difficile and had diarrhoea at the time of first culture, and 7 had diarrhoea or pseudomembranous colitis after 1-6 previously negative weekly rectal cultures. All patients with diarrhoea were on one ward, but symptom-free, excretors were found on all wards. HindIII chromosomal restriction endonuclease analysis (REA) of the C difficile isolates revealed 18 distinct types. All isolates from the patients with diarrhoea were one of two nearly identical REA types, B or B2. 26 of the 29 total B/B2 isolates were from patients on the same ward, which points to a nosocomial outbreak. The symptom-free excretors were not at increased risk of subsequent clinical illness.