Comparison of microscopy, ELISA, and real-time PCR for detectionof Giardia intestinalis in human stool specimens

Abstract

Background/aim: This study included patients who had digestive system complaints between August 2015 and October 2015. The research was designed to compare conventional microscopy with an antigen detection ELISA kit and the TaqMan-based real-time PCR (RT-PCR) technique for detection of Giardia intestinalis in human stool specimens.Materials and methods: Samples were concentrated by formalin-ether sedimentation technique and microscopic examinations were carried out on wet mount slides. A commercially available ELISA kit (Giardia CELISA, Cellabs, Brookvale, Australia) was used for immunoassay. DNA was extracted from fecal samples of about 200 mg using the QIAamp Fast DNA Stool Mini Kit (QIAGEN, Hilden, Germany) and the LightCycler Nano system (Roche Diagnostics, Mannheim, Germany) was used for the TaqMan-based RT-PCR assay.Results: A total of 94 stool samples, 38 of them diagnosed positive (40.4%) and 56 of them diagnosed negative by microscopy, were selected for evaluation by antigen detection and molecular assays. The prevalence of G. intestinalis infection was found as 46.8% (n: 44) and 79.8% (n: 75) by ELISA and RT-PCR, respectively. RT-PCR revealed by far the highest positivity rate compared to the other two methods. The difference between these methods was found to be statistically significant (P < 0.05). In comparison to PCR, the sensitivity and specificity of microscopy and ELISA were 50.7% and 100% and 53.3% and 79%, respectively. Conclusion:RT-PCR seems to be much more sensitive and beneficial for rapid and accurate diagnosis of G. intestinalis in human stools.

Molecular Characterization of Giardia duodenalis in Children and Adults Sampled in Algeria

“…Based on real-time PCR, the overall rate of Giardia duodenalis was 67%, with children being more commonly infected than adults (82% vs. 30%), confirming the trend identified in our previous study [25]. Real-time PCR was more sensitive for detecting Giardia than microscopy, which is in agreement with previous findings [32][33][34][35]. However, we identified seven samples negative by real-time PCR that were microscopy-positive for Giardia.…”

Molecular detection and genotyping of intestinal protozoa from different biogeographical regions of Colombia

“…Several studies have shown differences in detection rates using molecular tests, which allow identification of cryptic species and their genotypes in addition to detection (Morgan et al, 1998;Stensvold et al, 2018). Thus, there is clear value in using complementary techniques (Beyhan & Taş Cengiz, 2017;Sri-Hidajati et al, 2018;Mateo et al, 2014) for molecular epidemiological studies, which may help to better elucidate the transmission dynamics of microorganisms and to establish better prevention and control plans. Another advantage of using molecular techniques is their sensitivity in cases of polyparasitism (Meurs et al, 2017).…”

Burden and Epidemiology of Human Intestinal Giardia duodenalis Infection in Colombia: A Systematic Review

“…Many authors [ 75 , 76 , 77 , 78 , 79 , 80 , 81 ], indicated that PCR-based methods for the laboratory diagnosis of Giardiasis showed excellent specificity and sensitivity, compared with antigen detection, and microscopy.…”

“…Despite this, the sensitivity can be increased if other diagnostic techniques are added [ 86 , 87 ]. Nevertheless, the microscopy remains the mainstay of Giardia diagnosis despite its limitations, specially in the developing countries located in Latin America, Asia, and Sub-Saharan Africa with low or middle economic resources and poor access to health facilities [ 33 , 76 , 88 ].…”