Laboratory diagnosis of Clostridium difficile infection in Spain: a population-based survey.

A survey of laboratory diagnosis of Clostridium difficile infection (CDI) was conducted in 103 Spanish hospitals. A mean of 23.2 stool specimens/1000 admissions were processed to detect CDI. Overall, 35.9% of the laboratories specifically selected stool specimens for diagnostic C. difficile toxin testing. The most commonly used criteria were loose or watery stools, previous antibiotic therapy and nosocomial diarrhoea. Most laboratories (95.1%) processed the stool specimens in house, mainly five to seven days/week. All laboratories except one detected toxins directly in stool specimens, and 94.9% used enzyme immunoassays (EIAs). Only 16.3% of the laboratories used toxigenic culture as a diagnostic tool, and most of them used EIAs to detect toxins in isolates. The most common diagnostic strategy was toxin detection in stool specimens using EIA alone (79.6%), and the second most common strategy was the combination of toxin detection in stool specimens and isolates (10.2%). The estimated annual incidence of CDI was 1.71 cases/1000 admissions, and this was significantly higher in large hospitals. CDI is underdiagnosed in Spain because most laboratories use EIAs performed directly on stool specimens as the only diagnostic procedure. A national laboratory survey of diagnostic methods and testing protocols for the diagnosis of CDI is simple and inexpensive, and could act as the first step towards implementing national standardized criteria for optimal diagnosis of CDI.