Characterizing the profile transformation of Helicobacter pylori: increased secondary and multidrug resistance following failed eradication in Ningxia, China

Global antimicrobial resistance to Helicobacter pylori (H. pylori) has escalated significantly.This study aimed to investigate the primary and secondary resistance characteristics of clinical isolates of H. pylori in Ningxia region, and to assess the impact of the number of previous eradication treatment failures on the antibiotic resistance pattern.

The primary and secondary resistance rates of H. pylori to the six antibiotics were as follows: MET (94.3% vs. 97.5%), CLA (39.8% vs. 74.6%), LEV (40.5% vs. 68.2%), AMO (0.4% vs. 2.5%), FUR (0.0% vs. 0.0%), and TET (0.2% vs. 0.0%). With increasing numbers of treatment failures, the secondary resistance rates of MET, CLA, and LEV all rose significantly, exhibiting a linear correlation (all P < 0.001). In susceptibility testing, the inhibition zone diameter (IZD) of MET consistently fell within the resistant range, while those of CLA and LEV decreased markedly from the susceptible to the resistant range (all P < 0.001). The resistance rates of AMO, TET, and FUR remained consistently low and within the susceptible range; among them, AMO showed a slight reduction in IZD previously treated patients (P < 0.001), though the change was limited. Regarding resistance patterns, Primary drug-resistant strains were predominantly characterized by single (39.9%) and double resistance (35.8%), with the most common combination being MET + CLA/LEV. As treatment failures accumulated, the rate of double drug resistance peaked after the first failure (49.6%), while the rate of multidrug resistance continued to rise—from 21.1% in the treatment-naïve group to 75.0% in the group with ≥ 3 treatment failures (P < 0.001), primarily driven by the MET + CLA + LEV combination.

This study reveals the significant changes pattern of drug resistance of H. pylori in Ningxia region under the background of treatment failure: the resistance rates to MET, CLA and LEV are high, and the secondary resistance increases with the number of treatment failures. The drug resistance pattern shifts from single/double resistance to multiple resistance mainly involving MET + CLA + LEV. In contrast, the resistance rates to AMO, TET and FUR are low and remain stable.