Quantitative PCR of String-Test Collected Gastric Material: A Feasible Approach to Detect Helicobacter Pylori and Its Resistance Against Clarithromycin and Levofloxacin for Susceptibility-Guided Therapy.

Background: As the reduced eradication rate of Helicobacter pylori (H. pylori), we introduced string-test and quantitative PCR (qPCR) for susceptibility-guided therapy innovatively. The practicality of the string test was evaluated.Methods: It was an open-label, non-randomized, parallel, single-center study, in which subjects tested by C-13- urea breath test (UBT) and string-qPCR were enrolled. Based on the results of string-qPCR, we calculated clarithromycin and levofloxacin resistance rates and gave C-13-UBT positive patients 14 days susceptibility-guided bismuth quadruple therapy. In the empirical therapy group, we retrospectively analyzed the treatment results of C-13-UBT positive patients also treated with bismuth quadruple at Shenzhen Luohu People's Hospital from January 2021 to May 2022. The eradication rate was compared between susceptibility-guided therapy and empirical therapy groups.Results: The diagnosis of H. pylori infection using the string-qPCR had an overall concordance rate of 95.9% with the C-13-UBT results. Based on the results of string-qPCR, the clarithromycin and levofloxacin resistance rates were 26.1% and 31.8%, respectively. The patients who were given 14 days susceptibility-guided bismuth-based quadruple therapy achieved a high H. pylori eradication rate of 91.8%. Retrospective analysis of patient treatment data from January 2021 to May 2022 available in the hospital database revealed an overall success rate of 82.3% for those who received empirical bismuth-based quadruple therapies, which is marginally significantly lower than that of the string-qPCR susceptibility-guided group (p = 0.084).Conclusion: The high treatment success rate of 91.8% indicates that the string-qPCR test is a valuable and feasible approach for clinical practice to help improve H. pylori treatment success rate.