Missed diagnosis of Clostridium difficile infection; a prospective evaluation of unselected stool samples

Clostridium difficile infection (CDI) is the leading cause of hospital-acquired diarrhoea in developed countries, however a high proportion of CDI episodes go undiagnosed, either because physicians do not request identification of toxigenic C. difficile or microbiologists do not perform the appropriate tests.

To investigate the clinical characteristics of patients with CDI within a non-selected population and to determine risk factors for clinical underdiagnosis.

We conducted a prospective study in which systematic testing for toxigenic C. difficile on all diarrhoeic stool samples was performed regardless of the clinician's request. Patients aged >2 years positive for toxigenic C. difficile and diarrhoea were enrolled (Jan-June 2013) and monitored at least 2 months after their last episode.

We identified 204 cases of CDI, of which three-quarters were healthcare-associated. Most cases were mild to moderate (83.8%), the recurrence rate was 16.2%, and CDI-related mortality was low (2.5%). A significant proportion (12.7%) of CDI cases would have been missed owing to lack of clinical suspicion. Community-acquired cases and young age were risk factors for clinical underdiagnosis.

Our data support the introduction of a systematic search for toxigenic C. difficile in all diarrhoeic stools from inpatients and outpatients older than 2 years.