Clostridium difficile infections: do we know the real dimensions of the problem?

Clostridium difficile infection (CDI) is the primary cause of nosocomial diarrhoea in industrialised countries, usually occurring as a complication of antibiotic therapy in elderly patients. Landmark events contributed to boosting interest in CDI over the last 10 years, including the emergence of unusually severe and recurrent CDI due to the NAP1/BI/027 strain, as well as reports suggesting that CDI is also significantly encountered in patients previously considered at no risk, such as community-acquired CDI in patients with no recent antibiotic use, or CDI during pregnancy. Despite this growing interest from the medical community, we do not know the real dimensions of the disease for the following reasons: (i) despite comprehensive guidelines published in Europe and in the USA, most laboratories still use diagnostic tests with suboptimal sensitivity as a 'rule-out' test, hence a significant proportion of CDIs remain undiagnosed; (ii) use of PCR as a stand-alone test by others will probably overestimate the real incidence of CDI and jeopardise any comparison between institutions with different diagnostic procedures; and (iii) transversal studies, with optimum design and diagnostic tests, are rapidly outdated due to the dramatic changes in CDI epidemiology that may occur from one year to another. To get an accurate picture of the real dimensions of the CDI issue, we need more systematic use of an adequate and homogeneous diagnostic strategy in the field as well as the implementation of continuous monitoring of CDI incidence through surveillance programmes.