Are microscopy and culture enough to diagnose Dientamoeba fragilis: A preliminary study

Background: Detection of Dientamoeba fragilis has traditionally relied upon light microscopic examination of permanently stained fixed stool smears. Adding cultivation techniques improved the results come out. However, newer molecular detection techniques, such as PCR are becoming the methods of choice, even though these tests are not used routinely. Objectives: The current study used nested PCR (nPCR) to detect D. fragilis and compared the results with those of microscopy and culture. Patients and Methods: Fresh stool samples were collected from 100 children aged 6-12 y complaining of gastrointestinal disturbances. Samples were subjected to microscopic examination of iron hematoxylin stained smears, culture using a Loeffler’s culture medium and nPCR. Results: The study detected D. fragilis molecularly in 4% of samples (4/100) and by microscopy and culture on Loeffler’s medium in 2% (2/100). Molecular assay showed 100% sensitivity and specificity compared to microscopy (50%, and 95% respectively), and Loeffler’s culture medium (50%, and 100% respectively), respectively. Conclusion: Nested PCR offers superior accuracy over microscopy and culture for diagnosing D. fragilis infections. In cases where PCR is not accessible in a diagnostic lab, at least two alternative diagnostic methods should be employed.