Analysis of Routine and Integrative Data from Clostridioides difficile Infection Diagnosis and the Consequent Observations
Gabriella Piatti1, *, Marco Bruzzone2, Vincenzo Fontana2, Marcello Ceppi2
1 DISC, Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy
2 Unit of Clinical Epidemiology, Ospedale Policlinico San Martino, Genoa, Genoa, Italy
Clostridioides difficile Infection (CDI) is an acute disease that needs a fast proper treatment. Unfortunately, the diagnosis, and above all the understanding of the results, remain arduous.
This study analyzed routine and integrative results of all fecal samples from patients over time. Our aim was to understand the dynamics of CDI infection and the meaning of “difficult to interpret” results, to make physicians better understand the various tools they can use.
We evaluated routine results obtained from 815 diarrheal stools with Enzyme Immunoassay (EIA) that detects C. difficile Glutamate Dehydrogenase (GDH) antigen and toxin B. We also reanalyzed a part of samples using integrative tests: a Real-time polymerase chain reaction (RT-PCR) for C. difficile toxin B gene (tcdB) and the automated immunoassay VIDAS C. difficile system for GDH and toxins A/B.
EIA GDH positivity increased through multiple testing over time, with a P value <0.001, depicting a sort of bacterial growth curve. Eighty-five percent of GDH positive/toxin B negative, i.e., discrepant, samples PCR were tcdB positive, 61.5% of discrepant tcdB positive samples were VIDAS toxins A/B positive, and 44.4% of GDH EIA negative stools were VIDAS GDH positive.
The results confirmed the low sensitivity of the EIA system for C. difficile GDH and toxins, questioned the use of the latter for concluding any CDI diagnostic algorithm, and led us to indicate the algorithm beginning with tcdB molecular research, and continuing in positive cases with VIDAS CD GDH method, as the most effective for CDI.
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* Address correspondence to this author at DISC, Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, 10 Largo Benzi, 16132, Italy; Tel: 39 3204207437; E-mail:firstname.lastname@example.org