Comparison of three commercial multiplex PCR assays for the diagnosis of intestinal protozoa

Although microscopic examination of stool samples remains the reference method for the diagnosis of intestinal protozoal infections, these techniques are time-consuming and require operators who are experienced and well trained. Molecular biology seems to offer performances at least equivalent in terms of sensitivity and specificity for certain parasites. This study aimed to compare three multiplex PCR assays on 93 prospectively collected positive stools (prospective cohort) and a panel of 12 more Cryptosporidium -positive samples ( Cryptosporidium panel). On the prospective cohort, the sensitivity was 89%, 64% and 41% for Giardia sp. detection for BD Max TM , G-DiaPara TM and RIDA ® GENE, respectively and 75%, 100% and 100% for C. parvum/hominis detection. The sensitivity of the RIDA ® GENE assay for all Cryptosporidium species was 100%, and for D. fragilis 71%. All the techniques obtained the same results for E. histolytica detection, with one positive sample. All species in the Cryptosporidium panel were identified by the RIDA ® GENE PCR. The BD Max TM and G-DiaPara TM assays detected only C. parvum/hominis with the exception of one positive sample for C. meleagridis . No assay showed satisfactory results for all parasites simultaneously, and the DNA extraction seems to be the critical step. More studies are needed to standardize this procedure.