CLOSTRIDIUM-DIFFICILE-ASSOCIATED DIARRHEA - EPIDEMIOLOGIC DATA FROM WESTERN-AUSTRALIA

The incidence of Clostridium difficile-associated diarrhoea (CDAD) was investigated retrospectively at a 690-bed teaching hospital for the p eriod 1983-92. Our aims were to determine: (i) the distribution by age and sex of patients with CDAD. (ii) the possibility of a seasonal tre nd and, (iii) the influence of infection control procedures, contamina tion of the hospital environment and the use of third-generation cepha losporins. The laboratory diagnosis of CDAD was based on demonstration of the organism by stool culture and/or detection of specific cytotox in in stool filtrates. G. difficile was detected in 917 patients who w ere being investigated for diarrhoeal illness. Yearly isolations varie d from a low of 49 in 1983 to a high of 120 in 1990 (Chi square for li near trend 128.8; P < 0.005). Most patients were elderly, with 63% age d 60 years or more; the majority (59%) were female. The relationship b etween culture of C. difficile and detection of cytotoxin in faecal ex tracts was also examined. Sixty percent of a sample of 132 isolates fr om patients in whom faecal cytotoxin was not detected produced cytotox in in vitro, suggesting that culture is a more sensitive indicator of infection with C. difficile than cytotoxin detection. When the total n umber of faecal specimens received in the laboratory was used as a den ominator there was an increase in the number of incident cases of CDAD between 1983 and 1990, apart from 1986. When occupied bed days was us ed as the denominator a similar trend was observed with a peak in 1990 . These increases correlated with an increase in the use of third gene ration cephalosporins at SCGH between 1983 and 1989 (Pearson's correla tion coefficient. 0.90). The introduction of Body Substance Isolation in 1989, in conjunction with other infection control procedures, appea rs to have halted the rise, despite a continuing use of broad-spectrum cephalosporins. In order to reduce the number cases of CDAD, either a reduction in levels of environmental contamination or a reduction in the use of third-generation cephalosporins is required. If this can be achieved the economic consequences, in terms of an opportunity cost, will be considerable.