Background: Detection of D. fragilis relies upon microscopic examination of permanently stained fixed
stool smears, and/or culture. Although molecular diagnostic techniques, were developed for several
pathogens, those for D. fragilis are not used routinely.
Objective: To evaluate usefulness of nested PCR in diagnosis of D. fragilis.
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 in Loeffler's 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).
Conclusion: Nested PCR offers superior accuracy over microscopy and culture for diagnosis. In cases
where PCR is not accessible in a diagnostic laboratory, at least two alternative diagnostic methods should
be employed.