Low sensitivity of fecal toxin A/B enzyme immunoassay for diagnosis of Clostridium difficile infection in immunocompromised patients.
Clin Microbiol Infect. 2015 Jul 29;
Authors: Erb S, Frei R, Strandén AM, Dangel M, Tschudin-Sutter S, Widmer AF
Abstract
The optimal approach in laboratory diagnosis of Clostridium difficile infection (CDI) is still not well defined. Toxigenic culture (TC) or alternatively fecal toxin assay by cell cytotoxicity neutralization assay are considered the gold standard, but these methods are time-consuming and labor intensive. In many medical centers diagnosis of CDI is therefore still based on fecal toxin A/B enzyme immunoassay (EIA) directly from stool alone, balancing cost and speed against limited diagnostic sensitivity. The aim of the study was to assess in which patient population the additional workload of TC is justified. All consecutive stool specimens submitted for diagnosis of suspected CDI between 2004 and 2011 at a tertiary care center were examined by toxin-EIA and TC. Clinical data of patients with established diagnosis of CDI were collected in a standardized case-report form. From 12'481 stool specimens submitted to the microbiological laboratory, 480 (3.8%) patients fulfilled CDI criteria. 274 (57.1%) were diagnosed by toxin-EIA and additional 206 (42.9%) by TC when toxin-EIA was negative. Independent predictors for negative toxin-EIA, but positive TC were high-dose corticosteroids (OR 2.97, 95% CI 1.50-5.90, p=0.002), leukocytopenia <1'000/μl (OR 2.52, 95% CI 1.22-5.23, p=0.013), and non-severe CDI (OR 2.21, 95% CI 1.39-3.50, p=0.001). There was no difference in outcome like in-hospital mortality and recurrence between both groups. In conclusion, negative toxin-EIA does not rule out CDI in immunocompromised patients in the setting of relevant clinical symptoms. Methods with improved sensitivity such as TC or PCR should be used particularly in this patient population.
PMID: 26232535 [PubMed - as supplied by publisher]