RESUMO
PURPOSE: 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. CONCLUSION: 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.
RESUMO
The association between Helicobacter pylori (HP) infection and concentration of folate or homocysteine are still unclear. The aim of the present study was to assess the effect of HP infection on folate and homocysteine concentrations in patients infected with HP and healthy participants. We also assessed dietary intakes of folate, vitamins B6 and B12 in two groups. In this case-control study, 44 participants with HP-infection and 46 healthy controls were studied. Participants were recruited from those referred to the central laboratory of Tabriz University of Medical Sciences. Blood samples were collected to determine serum folate and homocysteine levels. The presence of both IgG and IgA in serum was considered as HP positive. Dietary intakes were assessed in all participants by 24-hour dietary recalls by trained interviewers for three days. The mean concentration of serum folate was significantly lower in HP-positive patients than in controls (8.49 nmol/L vs. 10.95 nmol/L, respectively; P=0.01). Although the mean concentration of serum homocysteine differed between groups, statistical significance was missed (HP infected patients: 9.35 µmol/L; healthy participants: 8.96 µmol/L; P=0.064). Macro- and micronutrient intakes showed no significant difference between participants with and without HP infection. In logistic regression models, there was a negative correlation between folate concentration and HP infection even after controlling for confounding factors (OR=0.82; CI95%=0.79-0.97). In this study, authors showed that a negative association presents between HP infection and serum folate concentrations, but the homocysteine status was not differed significantly between HP-positive and HP-negative participants.