Background: Resistance of Helicobacter pylori to clarithromycin is mostly due to the point mutations in the 23S rRNA. The aims of the present study were to determine mutations in domain V of 23S rRNA gene of Helicobacter pylori in chronic gastritis patients by sequencing; and to assess the association of these mutations with clarithromycin-resistant phenotype determined by E-test. Patients and methods: Gastric mucosal biopsy specimens from 170 patients with chronic gastritis were entered in the study. DNA was extracted from biopsy specimens obtained by endoscopy and prepared for sequencing domain V of gene 23S rRNA. 80 biopsy specimens were determined MIC by E-test. Results: Eight point mutations were detected. At 2142 and 2143 sites of gene, A2143G and A2142G mutations were detected in 35.3% and 3.5%, respectively. Six remaining mutations were G2172T (0.6%), T2182C (86.5%), C2195T (5.3%), A2223G (42.9%), T2244C (98.2%) và A2302G (8.8%). A2143G mutation was associated with clarithromycin-resistant phenotype, OR = 368.58 (95%CI: 34.53 – 3934.12). The rate of clarithromycin-resistance in the group with A2143G mutation was 96.7%, while in the group without A2143G mutation was 10%. Predicted probabilities for clarithromycin-resistance were calculated by logistic regression model with the accuracy rate of 96.1%. Conclusions: There was the association between A2143G mutation and clarithromycin-resistant phenotype. Genotypes determined by sequencing domain V of 23S rRNA gene could be used to predict the probabilities of clarithromycin-resistance. Key words: 23S rRNA gene, clarithromycin-resistance, Helicobacter pylori
Point Mutations in Domain V of the 23S rRNA Gene Are the Primary Cause of Clarithromycin Resistance in Clinical Helicobacter pylori Isolates in the United States