Molecular detection of Entamoeba histolytica in diarrheic fecal samples from patients attending National Hepatology and Tropical Medicine Research Institute

Abstract

Background: Amoebiasis is a worldwide disease caused by Entamoeba histolytica infection. The true prevalence is unknown due to the difficulty in distinguishing Entamoeba histolytica from non-pathogenic amoebas especially when microscopic diagnosis is performed, to overcome microscopy misidentification. Polymerase Chain Reaction (PCR) assay is necessary as a highly sensitive and specific technique. Objective: To determine the value of Real-Time PCR (RT.PCR) in the diagnosis of Entamoeba histolytica in the stool samples of diarrheic patients attending NHTMI versus microscopy, copro- antigen, and serum antibodies detection techniques. Subjects and Methods: A cross-sectional study was conducted on 150 diarrheic patients. Their stool samples were examined macroscopically and microscopically (by direct smear, parasep concentration, and formol-ether methods), by copro-antigen, and by RT.PCR and their blood samples were examined for serum Entamoeba histolytica antibodies by Indirect Hemagglutination (IHA). Results: Through RT. PCR (42%) were positive samples for Entamoeba histolytica, microscopy detected 64.7% positive samples with a sensitivity of 100% and specificity of 61.0%, copro-antigen detected 73.3% positive samples with a sensitivity of 100% and specificity of 85.1%, while serology detected 38.7% positive samples with sensitivity 92.1% and specificity 100%. Conclusion: The incidence of the true Entamoeba histolytica is lower when specific and sensitive diagnostic methods (RT.PCR/copro-antigen) are used, allowing to differentiate between pathogenic and other non-pathogenic amoebas that help to avoid the unnecessary treatment that relies on misdiagnosis as well as to reduce medical costs and hazards.