Investigation of frequency and determination of genotype profile of Dientamoeba fragilis in diarrheal patients with and without immune deficiency

Dientamoeba fragilis is a protozoon of the large intestine, which may lead to various gastrointestinal disorders and which is difficult to diagnose. As diagnostic procedure has not been standardized in our country yet, the aim of this study is to diagnose D. fragilis by using iron hemotoxylin stain and PCR methods, as well as to compare these methods, to study the effect of immune system on frequency of parasite and determine genotype profile of the parasite.Stool samples from ninety diarrheal patients with immune deficiency and 202 diarrheal patients without immune deficiency were investigated by iron hematoxylin staining and PCR method. RFLP method was applied for genotype profile, 18 positive samples underwent sequence analysis, and the results were evaluated.In the group with immune deficiency, D. fragilis was detected in two (2.2%) cases by the staining method, and in four (4.4%) by the PCR. Among the immunocompetent patients, D. fragilis frequency was identified as 22.8% (46/202) using the staining method, and as 24.3% (49/202) using the PCR method. Among all cases, D. fragilis positivity was 16.4% (48/292) with iron hematoxylin staining, and 18.5% (53/292) with PCR. The compatibility between the tests was good (Kappa=0.77, p=0.000). D. fragilis was significantly more prevalant in those with complaints of diarrhea accompanied by constipation, gas, dyspepsy, perianal itch, urticarial itch and peripheral eosinophilia. Eighteen PCR products underwent sequence analysis, and among the samples which were defined as İzmir 1, İzmir 2 ve İzmir 3; İzmir 1 and 3 were evaluated in the Genotype 1 group, and İzmir 2 in Genotype 2 group.As D. fragilis causes nonspesifik gastrointestinal symptoms, more importence should be given for its diagnose. The use of permanent staining for fixated samples, and even use of PCR method with chronic diarrhea or immundepressed patients will provide acsess to real frequency of dientamoebiosis.