A patient treated for amoebic colitis has cysts seen on stool microscopy reported as Entamoeba histolytica. Which additional test definitively confirms pathogenic E. histolytica rather than the morphologically identical commensal E. dispar?
- A Stool culture on Robinson's medium
- B Iron haematoxylin staining of the stool smear
- C Stool enzyme immunoassay for E. histolytica-specific galactose-inhibitable lectin antigen ✓
- D Serum indirect haemagglutination antibody titre
Correct answer: C. Stool enzyme immunoassay for E. histolytica-specific galactose-inhibitable lectin antigen
Explanation
E. histolytica and E. dispar cysts are morphologically indistinguishable, so species-specific stool antigen detection using the galactose-inhibitable lectin is required to confirm true pathogenic infection. Special stains and culture still cannot separate the two species visually, and serum antibodies persist for years after past infection, so they indicate exposure rather than current disease in endemic populations.
Reference: Paniker's Textbook of Medical Parasitology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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