AbstractClostridium difficile is the leading cause of infectious nosocomial diarrhoea in developed countries, with a measured incidence of approximately five episodes per 10 000 days of hospital stay in Europe. Accurate diagnosis of C. difficile infection (CDI) is a prerequisite for obtaining reliable epidemiological data, but in many European countries diagnosis is probably suboptimal. A significant percentage of CDI cases are missed because clinicians often fail to request tests for C. difficile toxins in cases of unexplained diarrhoea. In addition, some laboratories continue to use tests of low sensitivity or apply them inappropriately. In one study in Spain, failure to request CDI testing in more than two-thirds of patients with unexpla...