Comparison of Stool Antigen Detection Kits to PCR for Diagnosis of Amebiasis

Abstract

The present study was conducted to compare two stool antigen detection kits with PCR for the diagnosis of Entamoeba histolytica infections by using fecal specimens submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, and the Institute of Medical and Veterinary Science, Adelaide, Australia. A total of 279 stool samples containing the E complex (E. histolytica, Entamoeba dispar, and Entamoeba moshkovskii) were included in this study. The stool specimens were tested by using two commercially produced enzyme immunoassays (the Entamoeba CELISA PATH and TechLab E. histolytica II kits) to detect antigens of E. histolytica. DNA was extracted from all of the samples with a Qiagen DNA stool mini kit (Qiagen, Hilden, Germany), and a PCR targeting the small-subunit ribosomal DNA was performed on all of the samples. When PCR was used as a reference standard, the CELISA PATH kit showed 28% sensitivity and 100% specificity. The TechLab ELISA (enzyme-linked immunosorbent assay) kit did not prove to be useful in detecting E. histolytica, as it failed to identify any of the E. histolytica samples which were positive by PCR. With the TechLab kit, cross-reactivity was observed for three specimens, one of which was positive for both E. dispar and E. moshkovskii while the other two samples contained E. moshkovskii. Quantitative assessment of the PCR and ELISA results obtained showed that the ELISA kits were 1,000 to 10,000 times less sensitive, and our results show that the CELISA PATH kit and the TechLab ELISA are not useful for the detection of E. histolytica in stool samples from patients in geographical regions where this parasite is not endemic.

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

“…For fecal samples that were microscopy positive for Entamoeba complex, the TechLab E. histolytica II kit failed to detect any (0/18) of the PCR-positive samples. A sensitivity and specificity of 0% and 100%, respectively in comparison to PCR was thus reported for the TechLab E. histolytica II ELISA kit (Stark et al 2008). On the other hand, an Ecuadorian study conducted in an E. histolytica endemic area north of the country, reported a sensitivity of 14.3% and a specificity of 98.4% when compared to isoenzyme analysis.…”

“…Another reason attributed to the poor performance of the TechLab E. histolytica II ELISA kit is the fact that the assay recognizes the vegetative forms adhesin only, normally present in diarrheal fecal specimens during an acute amoebic infection and not the cyst stage (Gatti et al 2002). Yet, in a study by Stark et al (2008), where at least half of the patients were symptomatic and in the majority of the cases both trophozoites and cysts were present, ELISA kits still performed poorly. In addition, polymorphism in the lectin antigen used in the E. histolytica II ELISA may also explain the failure of this test (Beck et al 2002).…”

“…Both techniques are widely used nowadays for detecting and identifying E. histolytica in clinical samples. However, a notable disadvantage of stool antigen immunoassay kits is their inability to detect neither E. dispar nor E. moshkovskii in clin-*Corresponding Author: abuodeh@sharjah.ac.ae Ali ElBakri et al 186 ical samples (Haque et al 1998;Stark et al 2008). Many outstanding PCR assays for the specific detection and differentiation of E. histolytica, E. dispar and E. moshkovskii DNA in fecal specimens are available (Gutierrez-Cisneros et al 2010;Haque et al 2010;Paul et al 2007;Tanyuksel and Petri 2003).…”

Seroprevalence of Entamoeba histolytica Infection among Men Who Have Sex with Men in Sydney, Australia

“…4 Improved methods of detection, with greater sensitivity and specificity include antigen and antibody detection and polymerase chain reaction. 15,18 Serum antibody detection is most useful in patients with extra-intestinal disease and is able to detect antibodies specific for E. histolytica. Sensitivity of these tests is ~95% for patients with amoebic abscesses, 70-85% for patients with active amoebic colitis, and 10-20% for asymptomatic people passing cysts, with specificity of 95% generally reported, 19,20 and E. histolytica -specific antibodies persisting for many years after exposure.…”

Simple and Rapid Detection of Potato leafroll virus by Reverse Transcription Loop-mediated Isothermal Amplification

“…To increase sensitivity of virus detection by ELISA, sprouts from tubers have been used (Mumford et al, 2000). Conventional polymerase chain reaction (PCR) or reverse transcription-PCR (RT-PCR) which have high sensitivity and specificity over ELISA-based methods and have been used to detect DNA viruses or RNA viruses, respectively (Bostan and Peker, 2009;Stark et al, 2008;Zaghloul, 2011). RT-PCR and immunocapture reverse transcription polymerase chain reaction (IC-RT-PCR) have been employed for detection of PLRV in plant or in aphid vectors (Ahouee et al, 2010;Hadidi et al, 1993;Peiman and Xie, 2006;Singh et al, 1995;1997).…”