Objective: Dientamoeba fragilis is an intestinal protozoan found in colonic lumen and it has been demonstrated that it can lead to various gastrointestinal and dermatological complaints. It has been discussed lately that D. fragilis can be found also in high prevalence among healthy individuals and could be a member of healthy gut microbiota. The aim of this study was to compare the prevalence of D. fragilis between patient and healthy-control groups from Istanbul, and to study clinical outcomes of the infection it causes on the patient group ,and patient characteristics.

Method: Stool samples of 184 patients admitted to Acıbadem Health Group hospitals in Istanbul between 2016-2018, and 156 healthy controls were examined in the study. After microbiological and parasitological assessments of stool samples, DNA isolation was made followed by conventional PCR test using specific primers.

Results: D. fragilis was detected in 15 of 184 (8.2%) patients and 42 of 156 (26.9%) controls, and the intergroup difference was significant (p<0.05). In the study group Salmonella spp. was detected in 3, and Rotavirus in 1 of the D. fragilis positive individuals. Six out of 15 D. fragilis positive individuals in the study group were women and their average age (n=24.3) was higher than other groups (p=0.25). Fifty-five of 57 (96.5%) D. fragilis positive individuals were in the pediatric age group. The leading complaints were diarrhea, anorexia and abdominal pain, while 3 of the 15 patients reported itching and urticaria.

Conclusion: These preliminary results related to the metropolitan city of Istanbul tend to support the fact that D. fragilis may show pathogenic effects in some cases but it is more common among healthy individuals. Considering the similar results from different regions of the world, further studies are essential to unveil under which conditions D. fragilis is silent (friend) and acts as a pathogen (foe).