Entamoeba histolytica and Entamoeba dispar:comparison of two PCR assays for diagnosis in a non-endemic setting

Detection of Entamoeba histolytica, the causative agent of amoebiasis, is an important goal of the clinical parasitology laboratory. The identification of Entamoeba dispar as a morphologically identical but non-pathogenic species has highlighted the need for nonmicroscopic detection methods able to differentiate between the two organisms. In this study we evaluated the utility of conventional PCR and real-time PCR as methods for identification and differentiation of E. histolytica and E. dispar. The second aim of this study was to determine the relative proportions of infections caused by E. histolytica and the non-pathogenic E. dispar, allowing a picture of the epidemiological situation in a non-endemic setting to be obtained. One hundred and sixty-six clinical samples (faecal and liver abscess samples and one intestinal biopsy) belonging to 108 patients were analysed. More patients with E. dispar infection (8.3%) than patients with E. histolytica infection (5.6%) were found by both PCR assays. It is concluded that routine diagnosis of invasive amoebiasis performed by a combination of microscopy, culture and serology should be complemented with a PCR assay such as real-time PCR that offers a practical and clinically acceptable alternative for rapid and accurate diagnosis of amoebic infection in patients presenting with symptoms indicative of this disease.