Laboratory Diagnostic Techniques for Entamoeba Species

Abstract

SUMMARY The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.

Differential detection of Entamoeba histolytica, Entamoeba dispar and Entamoeba moshkovskii in fecal samples by nested PCR in the United Arab Emirates (UAE)

“…1997). Most E. histolytica infections are asymptomatic; however few strains of E. histolytica may invade the intestinal wall resulting in amoebic colitis or extraintestinal diseases such as ALA (Fotedar et al 2007). Despite its inability to distinguish and differentiate E. histolytica from the morphologically identical nonpathogenic species E. dispar and E. moshkovskii, microscopy has always been used to diagnose E. histolytica in fecal samples.…”

Amebiasis: aspectos clínicos, terapéuticos y de diagnóstico de la infección

“…Los grupos con mayor riesgo de tener una evolución grave son los niños, ancianos, desnutridos y los pacientes que reciben terapia con corticoides 12 . Las complicaciones incluyen estrechez u obstrucción intestinal, fístula rectovaginal, ameboma, megacolon tóxico, ulceración perianal y perforación intestinal con peritonitis, shock y deceso 35 . Se ha descrito la amebiasis intestinal crónica con diarrea y dolor abdominal intermitentes y períodos de constipación 24 .…”

“…Las complicaciones incluyen infección bacteriana, ruptura del absceso hacia la cavidad pleural, pericardial y peritoneal, shock séptico y muerte. Pueden ocurrir, raramente, metástasis amebianas hacia otros órganos 35 .…”

“…Las técnicas de PCR se han convertido en los métodos de elección por su excelente sensibilidad y especificidad en el diagnóstico de la infección y por la detección y capacidad para diferenciar las tres especies de Entamoeba morfológicamente indistinguibles 35 . La aplicación de estas técnicas es factible principalmente en países industrializados, donde la amebiasis afecta especialmente algunos grupos de alto riesgo 12 .…”

Efficiency of Direct Microscopy of Stool Samples Using an Antigen-Specific Adhesin Test for Entamoeba Histolytica

“…Recently, World Health Organization (WHO) recommends to make a specific diagnosis of E. histolytica in the developing countries by using improved diagnostic methods specific for E. histolytica and technologies developed for these countries (2). Currently, specific methods to detecting E. histolytica specific adhesin antigen in the stool sample show higher specificity and sensitivity in differential diagnosis (3)(4)(5). Rapid and definitive diagnosis of amoebiasis is important for administering treatment in the early stage.…”