High rates of Dientamoeba fragilis and Blastocystis species in children's stool but minor clinical significance

Objective: The aim of this study was to describe the epidemiology and the clinical significance of Dientamoeba fragilis (DF) and Blastocystis (Bs) in pediatric stool samples. Methods: A historical cohort study of children under 18 years of age who underwent stool multiplex PCR for bacteria and parasites. DF and Bs results were not routinely reported. We assessed the frequency of various stool microorganisms and analyzed a composite of symptoms occurring within 14 days before testing and four post-test composite outcomes (symptoms, further medical evaluation, prescriptions of symptomatic treatment or antibiotics). Comparisons were made between children mono-infected with DF or Bs, those with negative PCR results, and those positive for microorganisms with established pathogenicity. Results: Of 36,008 eligible children, 32.5% were positive for DF and 7.9% for Bs. Children positive for DF or Bs did not exhibit higher odds for pre- or post-test composite outcomes compared to those with all-negative PCR results, except for increased rates of abdominal pain and referrals for anti-TTG testing among DF-positive children. Antibiotic prescription was significantly more common among those positive for microorganisms of known pathogenicity. Conclusions: While DF and Bs are frequently detected in pediatric stool samples, their clinical significance appears to be limited.