Comparison of Diagnostic Accuracy Between Stool Staining and Polymerase Chain Reaction in Diagnosing Intestinal Microsporidiosis

Abstract

Microsporidia are intracellular parasites that cause chronic diarrhea, particularly in immunocompromised individuals, where access to molecular diagnostics remains limited. A 27-year-old man with HIV on antiretroviral therapy presented with a 10-day history of profuse watery diarrhea. Initial stool examinations using modified Ziehl–Neelsen staining were negative, and PCR testing was not available, raising suspicion of intestinal microsporidiosis. The clinical question was whether, in immunocompromised patients with suspected intestinal microsporidiosis, stool smear staining methods are as accurate as PCR in terms of sensitivity and specificity. A structured literature review was conducted using PubMed, Cochrane, and Google Scholar for studies published up to 2025, using keywords including microsporidia, Enterocytozoon, Encephalitozoon, intestinal, diarrhea, diagnosis, detection, staining, and PCR. Eligible studies included those evaluating stool-based staining methods against PCR in immunocompromised patients. Articles were appraised using the STARD 2015 guideline and independently reviewed by two reviewers. Of 70 identified articles, 3 met the inclusion and validity criteria. Modified trichrome (MT) staining showed sensitivity ranging from 38.6% to 90.0% and specificity from 88.9% to 100%. Calcofluor white (CW) showed sensitivity ranging from 70.4% to 96.7% and specificity from 68.4% to 82.4%. Although PCR remains the reference standard, MT staining offers acceptable diagnostic performance and is a practical alternative in settings where molecular testing is not feasible.