Assessment of Cryptodiag for Diagnosis of Cryptosporidiosis and Genotyping Cryptosporidium Species▿

The performance of a new commercial PCR-enzyme-linked immunosorbent assay (ELISA) (Cryptodiag; Bio Advance, France) for the diagnosis of cryptosporidiosis and the identification of Cryptosporidium hominis and C. parvum from stool samples was examined. This test is based on PCR amplification of Cryptosporidium DNA extracted from stools, followed by an ELISA based on hybridization with Cryptosporidium sp.-, C. hominis-, or C. parvum-specific probes. In spiking experiments, approximately five oocysts were detected either in water or in stool suspensions while assessing for the efficient removal of stool PCR inhibitors. No cross-reactivity was observed in the detection of C. parvum and C. hominis using the respective specific probes. Thirty-three fecal samples from patients with microscopically proven cryptosporidiosis and 118 from patients with or without other digestive protozoan infections were tested by Cryptodiag, blinded to the results of microscopy. Compared to microscopy, the sensitivity of Cryptodiag was 97.0% (32/33) and 100% (33/33), including the gray zone, and specificity was 98.3% (116/118) and 96.6% (114/118), including the gray zone. Among 34 positive results, Cryptodiag identified 19 due to C. hominis, 8 due to C. parvum, and 7 due to Cryptosporidium spp. Genotyping by Cryptodiag agreed with reference typing methods in 85% of cases of C. parvum or C. hominis infections. Cryptodiag proved to be reliable and sensitive for the diagnosis of cryptosporidiosis. The use of specific probes allowed the identification of C. hominis and C. parvum, i.e., the two main species responsible for human cryptosporidiosis, and rapidly provided information on the possible source of infection