Comparison of PCR and Serological Tests for the Assessment of CagA Status in Dyspeptic Patients

Background/Aims: Infection with CagA-positive Helicobacter pylori(H. pylori) may be diagnosed by detecting cagA gene by PCR or serum antibodies against CagA by western blotting or ELISA. The aim of this study was to evaluate whether results of PCR and serologic tests were in agreement in CagA status assessment. Methods: Sera and specimens of the gastric antral mucosa were obtained from 37 patients with functional dyspepsia. The diagnosis of H. pylori infection was made by histologic examination and rapid urease test. CagA status was assessed by PCR from antral biopsy specimens and by western blotting and ELISA of serum. The degree of gastric inflammation was evaluated by use of Sydney system. Results: Twenty-three patients (69.7%) were found to be H. pylori positive. The percent agreements of each tests for the assessment of CagA status were 65.2%(PCR vs western blotting), 60.9% (PCR vs ELISA), and 78.3%(western blotting vs ELISA) in the H. pylori infected patients. The results of all three tests agreed in only 12 patients(52.2%). CagA status assessed by any tests had no relationship with histologic parameters. Conclusions: Our results indicate that there is a considerable discrepancy between the results of three tests for the assessment of CagA status. Further studies are needed to find out the more exact methods for the detection of CagA.ope