Comparison of BD Max Cdiff and GenomEra C. difficile molecular assays for detection of toxigenic Clostridium difficile from stools in conventional sample containers and in FecalSwabs.

In this study, the usability and performance of GenomEra™ C. difficile and BD Max™ Cdiff nucleic acid amplification tests (NAATs) for the detection of toxigenic Clostridium difficile were investigated in comparison with toxigenic culture and C. difficile toxin A- and toxin B-detecting immunochromatographic antigen (IA) test, the Tox A/B QuikChek®. In total, 302 faecal specimens were collected, 113 of which were in parallel to conventional sample containers and FecalSwab liquid-based microbiology (LBM) tubes. Seventy-nine specimens were considered true-positives for toxigenic C. difficile. The sensitivity and specificity were 97.5 % and 99.6 % and 93.7 % and 98.7 % for the GenomEra and BD Max assays respectively. Toxigenic culture and Tox A/B QuikChek had sensitivity and specificity of 91.1 % and 100 % and 34.2 % and 100 % respectively. Hands-on time for analysing 1 to 24 specimens using NAATs was 1 to 15 min. The rate of PCR inhibition was 0 % for both NAATs with faeces in LBM tubes, while with faeces in conventional sample containers the respective inhibition rates were 5.3 % and 4.4 % for the GenomEra and the BD Max assays. The NAATs demonstrated an excellent analytical performance, reducing significantly the overall workload of laboratory personnel compared with culture and IA test.