Comparison of Sensitivity of Enzyme Immunoassays for Toxin A and B in different C. difficile PCR Ribotypes

Enzyme immunoassays (EIAs) for toxins A and B are the most common assays for the diagnosis of Clostridium difficile infection due to their rapidity and ease of use. However, the sensitivity of different kits varies greatly. The predominant PCR ribotypes of C. difficile vary according to the region or country studied, and it was recently reported that the sensitivity of EIAs can be affected by the strain type. The aim of this study was to assess the sensitivity of EIAs in different PCR ribotypes of C. difficile during a period of five years in a Korean hospital. A total of 969 toxigenic C. difficile isolates were recovered from patients with diarrhea in a hospital from 2006 to 2009 (inclusive), and 2011. Overall sensitivities of Tox A/B Quik Chek (TechLab, Blacksburg, VA) and VIDAS C. difficile A & B (bioMerieux, Marcy l'Etoile, France) were 36.4% and 46.3%, respectively. The sensitivities of TOX A/B Quick Chek and VIDAS Clostridium difficile A & B for the five most common ribotypes were as follows: 56.6% and 71.7% for ribotype AB17 (ribotype 018); 48.6% and 54.3% for ribotype aB (ribotype 017); 25.3% and 36.3% for ribotype AB2 (ribotype 014); 13.0% and 24.2% for ribotype AB3; 66.7% and 0% for ribotype AB17 (ribotype 001), respectively. The sensitivity for the predominant ribotype, AB17, was significantly different from those for aB, AB2, AB1, and AB3 using VIDAS Clostridium difficile A & B (p<0.05). These data suggest that the sensitivity of EIA may be affected by the distribution of ribotypes.