Background: A2143G mutation of 23S rRNA gene of H. pylori results in clarithromycin (CLR) resistance. To investigate the prevalence of the CLR resistance-related A2143G mutation of the H. pylori-specific 23S rRNA gene in Chinese subjects with and without CLR use history, 307 subjects received the treatment with amoxicillin and omeprazole (OA) and 310 subjects received a placebo in 1995, and 153 subjects received a triple therapy with OA and CLR (OAC) in 2000. DNA was extracted from fasting gastric juice at the end of the intervention trial in 2003. H. pylori infection was determined by H. pylori-specific 23S rRNA PCR, ELISA, and13C-urea breath test assays. Mutations of the 23S rRNA gene were detected by RFLP assays.
Results: The presence of 23S rRNA due to H. pylori infection in the OA group remained lower than that in the placebo group 7.3 yrs after OA-therapy [51.1% (157/307) vs. 83.9% (260/310), p = 0.0000]. In the OAC group, the 23S rRNA detection rate was 26.8% (41/153) three yrs after OAC-treatment. The A2143G mutation rate among the 23S rRNA-positive subjects in the OAC group [31.7% (13/41)] was significantly higher than that in the OA group [10.2% (16/157)] and the placebo group [13.8% (36/260)]. The frequency of the AAGGG --> CTTCA (2222-2226) and AACC --> GAAG (2081-2084) sequence alterations in the OAC group was also significantly higher than those in the OA group and the placebo group.
Conclusion: Primary prevalence of the A2143G mutation was 10~14% among Chinese population without history of CLR therapy. Administration of CLR to eliminate H. pylori infection increased the prevalence of the A2143G mutation in Chinese subjects (32%) significantly.