Drug resistance and clarithromycin resistance gene mutations in Helicobacter pylori strains circulating in Changchun area / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the resistance of Helicobacter pylori (H. pylori) strains to common antibiotics and to analyze the sites of genetic mutations carried by clarithromycin-resistant strains in order to provide reference for selecting sensitive antibiotics against H. pylori and for providing individualized treatment for patients in Changchun area. Methods Drug resistance of H. pylori clinical isolates to common antibiotics was detected by disk dilution method. The 23S rRNA genes of clarithromycin-resistant strains were amplified by PCR and then sequenced to analyze the presence of mutations. Results In this study, 69 strains of H. pylori were successfully isolated with a positive rate of 23. 1％ . Results of the drug susceptibility test to seven commonly used antibiotics showed that there were 52. 2％ of the isolates resistant to clarithromy-cin, 47. 8％ to tinidazole, 37. 7％ to levofloxacin, 33. 3％ to tetracycline hydrochloride, 30. 4％ to furazoli-done, 30. 4％ to metronidazole and 5. 8％ to amoxicillin. Amoxicillin could continue to be used as a first-line antimicrobial agent. Seven mutation sites were found in the 23S rRNA genes carried by the clarithromy-cin-resistant strains, which were A1821G, G1826A, T1830C, G1940A, A2143G, T2182C and A2223G. The A2143G site mutation accounted for 54. 2％ and was the predominant mutation resulting in the resistance to clarithromycin of H. pylori strains circulating in this area. Conclusions The H. pylori strains isolated from patients with gastroduodenal diseases in Changchun area had a high resistance rate to clarithromycin, which was mainly caused by the A2143G mutation in 23S rRNA gene.