Evaluation of the Liaison® C. difficile GDH System

Objectives. The aim of our study was to evaluate the LIAISON® system for the detection of GDH of C. difficile by comparing the results with those obtained with the our routine EIA test, from both of unselected samples and selected samples according to the Bristol scale for stool consistency. Study Design. We examined 114 unselected stool samples (Group 1) and 104 selected samples according to the Bristol scale (type 4-7: Group 2) for the detection of GDH with enzyme immunoassay (EIA) and chemiluminescence LIAISON® system. In case of positivity for one or both tests toxins A and B were searched, with EIA, and, in case of negativity of the toxins, the test of gene amplification for the search of the locus of pathogenicity for toxins A and B was performed. Results. In Group 1, sixteen samples were positive for both tests for GDH, 93 negative for both tests, and five discordant (three EIA positive and LIAISON® negative; two EIA negative and LIAISON® positive): total concordance between the two methods: 95.6%. Of the five discordant samples, all were toxin A & B negative, of these only one was positive to molecular biology. In Group 2, fifteen samples were positive for both tests for GDH, 89 negative for both tests and no discordant: total concordance between the two methods: 100%. Conclusions. Our data indicate a perfect correlation between LIAISON® and EIA, when samples are chosen according to stool consistency at least grade 4 of the Bristol scale.The possibility to use an automatic and fast system, like LIAISON®, also allows an optimization of workflows.