Evaluation of the Allplex(TM) Gastrointestinal Panel—Parasite Assay for Protozoa Detection in Stool Samples: A Retrospective and Prospective Study

This study aims at evaluating the performances of the multiplex PCR Allplex(TM) Gastrointestinal Panel-Parasite Assay (GIPPA), which detects G. duodenalis, Cryptosporidium spp., E. histolytica, D. fragilis, B. hominis, and C. cayetanensis, by comparison to microscopy. A retrospective evaluation was conducted on a series of positive clinical samples (n = 99) stored at −80 °C or at +4 °C. A five-month prospective study was then conducted on all samples sent to our lab for parasite detection (n = 586). In the retrospective cohort, sensitivity was 81% for both G. duodenalis (26/32) and D. fragilis (21/26) and 100% for Cryptosporidium spp. (26/26, including 6 different species), B. hominis (26/26), and C. cayetanensis (4/4). During the prospective study, 95 samples were positive by microscopy and 207 by multiplex PCR assay. The molecular assay showed a significantly higher sensitivity of PCR, especially for G. duodenalis (100% vs. 60.7%, p < 0.01), D. fragilis (97.2% vs. 14.1%, p < 0.001), and B. hominis (99.4% vs. 44.2%, p < 0.001) but also for E. histolytica (100% vs. 50.0%). The sensitivity of the Allplex(TM) GIPPA on the first stool sample was equivalent to the sensitivity of microscopy on multiple stool samples but inferior to multiplex PCR on multiple stool samples. Taken together, the Allplex(TM) GIPPA is suitable for the routine detection of protozoa in fecal samples.