Measuring the incidence of Clostridium difficile-associated diarrhoea in a group of Western Australian hospitals

Clostridium difficile-associated diarrhoea (CDAD) is a well known healthcare-associated infection, increasing in incidence and severity in much of the developed world. Recommendations for surveillance of CDAD have been published, and CDAD incidence monitoring is increasingly recommended internationally, but unlike many other healthcare-associated infections, there is little comparative data available about CDAD rates in hospitalised patients in Australia. Nine hospitals in Western Australian used standardised definitions and methods to calculate CDAD incidence rates over a 6-month period in 2006, and tested the feasibility of using these protocols in a local context. The overall incidence rate of healthcare-associated CDAD was 1.2 per 10 000 occupied bed days (range 0-3.3 per 10 000 occupied bed days). Calculated rates and hospital rankings varied markedly if separations were used in place of occupied bed days. Each data collection form took a median of 10 min to complete. The short study period and marked variation in laboratory diagnostic practices are limitations to direct comparison of rates between hospitals, but this is a useful and practical method of monitoring CDAD that can be easily incorporated in Australian infection control practice.