Comparative Evaluation of RUT, PCR and ELISA Tests for Detection of Infection with Cytotoxigenic H. pylori.

Farzaneh Jalalypour,Rana Yousefzadeh,Mohammad Hossein Somi,Zoya Hojabri,Nazli Saeedi,Safar Farajnia

doi:10.15171/apb.2016.036

Abstract

Helicobacter pylori is one of the most prevalent infectious agents in the world which causes a variety of gastrointestinal diseases including gastritis, peptic ulcer and gastric carcinoma. The objective of this study was to comparatively evaluate invasive (rapid urease test and polymerase chain reaction) and non-invasive (enzyme-linked immunosorbent assay) tests in diagnosis of infection with cytotoxigenic H. pylori. Biopsy specimens and sera were collected from 105 patients with gastric disorders. The presence of H. pylori infection in gastric biopsies was evaluated by RUT and PCR methods using chemotaxis signal transduction protein gene (CSTP), Urea C and HP-16srRNA primers. Serum samples were used for the ELISA test. Detection of infection with cag A-positive strains was performed by PCR and cag A-IgG ELISA kit. Patients with at least two out of three positive results were regarded as infected. The sensitivity, specificity, predictive value and accuracy of the three different methods were evaluated. Of the 105 gastric biopsies, H. pylori were positive in 51 patients (48.57%). The best sensitivity (92.16%) belonged to RUT. The sensitivities of other tests including PCR and ELISA test were 88.24% and 90.20%, respectively. PCR showed the best specificity (94.44%), and the specificities of the other tests including RUT and ELISA test, were 90.74 % and 61.11%, respectively. Furthermore, results of PCR and cag A-IgG ELISA showed high prevalence of cag A-positive strain in the study population. Based on our findings, serum ELISA is a rapid noninvasive test for screening of H. pylori infection in the absence of endoscopy indication. In addition, considering the high prevalence of cytotoxigenic H. pylori strains, cag A is suggested as a promising target for PCR and non- invasive ELISA tests for detection of infection with toxigenic strains.

Highlights

Helicobacter pylori (H. pylori) is a Gram-negative, microaerophilic bacterium which was identified in 1982 by Marshall and Warren.[1,2] H. pylori is one of the most common human-specific pathogens which exclusively inhabits the gastric mucosa.[3]
Infection with H. pylori is always associated with chronic gastric inflammation, gastritis and peptic ulceration which can lead to gastric cancers such as adenocarcinoma, lymphoma of the stomach or benign mucosal-associated lymphoid tissues (MALT).[4,5]
rapid urease test (RUT) test presented the best sensitivity of 92.16 %, but specificity of 90.74% which was lower than the polymerase chain reaction (PCR) method

Summary

Introduction

Helicobacter pylori (H. pylori) is a Gram-negative, microaerophilic bacterium which was identified in 1982 by Marshall and Warren.[1,2] H. pylori is one of the most common human-specific pathogens which exclusively inhabits the gastric mucosa.[3] Infection with H. pylori is always associated with chronic gastric inflammation, gastritis and peptic ulceration which can lead to gastric cancers such as adenocarcinoma, lymphoma of the stomach or benign mucosal-associated lymphoid tissues (MALT).[4,5] H. pylori infection is prevalent throughout the world and more than half of the world population harbors this organism.[6] There is a higher incidence of infection in less developed and developing countries.[7,8] The prevalence of H. pylori in the Iranian population is around 80% in adults and 50% in children,[9] beginning at infancy.[10]

Objectives

Methods

Findings

Conclusion