Abstract: Objective To study the detection and drug resistance of Helicobacter pylori （H. pylori） in patients with chronic gastritis. Methods A total of 2 259 patients with chronic gastritis diagnosed and treated at a hospital in Jinan City from July 2021 to December 2022 were selected for this study. The presence of H. pylori was detected using the ¹³C-urea breath test, and samples were collected from biopsy of the gastric mucosa for culture. The drug-resistant phenotype of H. pylori to metronidazole, levofloxacin, amoxicillin, and clarithromycin was detected in vitro, and the corresponding antibiotic-resistant genes were detected using sequencing methods. Results A total of 839 cases were detected as positive for H. pylori, with a positive detection rate of 37.14%. A total of 758 strains of H. pylori were isolated and cultured, the resistance rates to metronidazole, levofloxacin, amoxicillin, and clarithromycin were 51.98%, 31.13%, 1.00%, and 19.26%, respectively. There was no significant difference in drug resistance rates among H. pylori positive patients of different genders （P>0.05）. However, the drug resistance rate of H. pylori positive patients who had used the above-mentioned drugs was significantly higher than that of those who had not used the corresponding drugs （P<0.05 or P<0.01）. Although no statistically significant difference was observed in the resistance rate to metronidazole and amoxicillin （P>0.05）, there was a statistically significant difference in the resistance rate to levofloxacin and clarithromycin （P<0.05 or P<0.01） in H. pylori positive patients of different ages. The resistance gene of H. pylori to metronidazole was rdxA, and the mutation rates at T184G, G616A, and C148T sites were 70.98%, 43.01%, and 6.86%, respectively. The resistance gene of H. pylori to levofloxacin was gyrA, and the mutation rates at G261G, C261A, G271A, and A272G sites were 7.39%, 5.80%, 7.39%, and 3.96%, respectively. The resistance gene of H. pylori to amoxicillin was pbplA, and the mutation rates at A1777G and C1667G were 10.03% and 4.49%, respectively. The resistance gene of H. pylori to clarithromycin was 23SrRNA, and the mutation rates at T2182C, A2142G, and A2143G were 34.30%, 2.37%, and 20.32%, respectively. Conclusions Patients with chronic gastritis have high rates of H. pylori detection and their drug resistance is not promising. Effective interventions based on the resistance of commonly used antibiotics and the results of related genetic tests should be implemented, and individualized eradication therapies guided by resistance detection should be implemented to promote the eradication of H. pylori.

Key words: Helicobacter pylori, Chronic gastritis, Drug resistance, Antibiotics, Drug resistance gene