Prevalence of A2143G, A2142G and A2142C mutations in producing Helicobacter pylori strains resistance to clarithromycin in Charmahal and Bakhtiari Province

Current therapeutic regimens used for eradication of H.pylori consist of two antibiotics with proton pump inhibitors and bismuth compounds. Clarithromycin is the most important antibiotic used for treatment of H.pylori infection in Iran. The aim of this study was to identify clarithromycin resistance in H.pylori strains and evaluate role of A2143G, A2142G and A2142C of 23SrRNA point mutations in producing resistance to this drug. This was a cross-sectional study which included 263 patients who had referred to endoscopy department of Hajar hospital, in Shahrekord city, in 2007. Biopsy samples were cultured on brucella agar medium and incubated. For identification of H.pylori gram stain, urease, catalase, oxidase tests were used and PCR method was used to identify Urec gene. Standard method of NCLSI (National Clinical and Laboratory Standards Institute) was used for assessment of clarithromycin resistance. Specific primers and restriction enzymes BsaI and MboII were used to detect A2143G and A2142G mutations by PCR-RFLP method. Also for determination of A2142C mutation, specific primers and PCR method were used. Isolation of 84 strains of H.pylori (31.94%) was confirmed by means of PCR method. Among 19 (22.62%) of clarithromycin resistant strains, 13 (68.40%), 3 (15.78%) and 2 (10.52%) had A2143G, A2142G, A2142C mutations respectively and one unknown mutation was detected in 23SrRNA gene. Because of considerable resistance to clarithromycin, precise diagnosis of this mutation by molecular approach in other parts of the country seems necessary.