Validity of various diagnostic tests to evaluate cure of Helicobacter pylori infection.

Many diagnostic methods have been developed and used for detecting Helicobacter pylori to evaluate the success of treatment of H. pylori infection. We investigated and compared the suitability of the rapid urease test (RUT), polymerase chain reaction (PCR), 13C-urea breath test (13C-UBT), and serology with culture for evaluating cure of H. pylori infection. Forty-seven H. pylori-positive gastric ulcer patients received dual therapy of lansoprazole (30 mg u.i.d.) and clarithromycin (200 mg b.i.d.). Four weeks after the completion of treatment, RUT, PCR, 13C-UBT, and culture were performed and the negative rates of these tests were compared. Anti-H. pylori IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) before and 4 weeks after completion of the treatment to evaluate changes of titers during the treatment. The negative rate of RUT (55%) was significantly greater than that of culture (27%). Significant declines in titers were seen in the patients who had negative culture results, while the decline in the titer was not significant in the patients who had positive results. PCR assay and 13C-UBT were suitable for the evaluation of H. pylori eradication, but RUT was not suitable, because of its sensitivity. By monitoring anti-H. pylori IgG antibody titers, therapeutic failure can be detected early after completion of treatment.