title: Comparative Evaluation of RUT, PCR and ELISA Tests for Detection of Infection with Cytotoxigenic H. pylori.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Jalalypour
authors.affiliation: Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Safar
authors.initials: S
authors.lastname: Farajnia
authors.affiliation: Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Somi
authors.affiliation: Infectious and tropical Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Zoya
authors.initials: Z
authors.lastname: Hojabri
authors.affiliation: Infectious and tropical Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Rana
authors.initials: R
authors.lastname: Yousefzadeh
authors.affiliation: Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Nazli
authors.initials: N
authors.lastname: Saeedi
keywords: Cag A; Enzyme-Linked Immunosorbent Assay; Helicobacter pylori; Polymerase Chain Reaction; Rapid Urease Test