LAUSR

OBJECTIVES In Malaysia, the prevalence ofHelicobacter pylori resistance towards clarithromycin is increasing. This study aims to determine the mutations in the 23S rRNA domain V directly using bacterial DNA extracted from gastric biopsy specimens with urease positive result. METHODS A 1085-bp fragment of 23S rRNA domain V of 62 treatment-naïve samples withH. pylori infection was amplified via polymerase chain reaction with new designed primers, followed by sequencing. RESULTS Of the 62 cases, 42 patients were treated with clarithromycin-based triple therapy and 20 patients were treated with amoxicillin and proton pump inhibitors, both therapies showed successful eradication rates of 70% - 73.8%. Sequencing analysis detected 37 mutation points (6 known and 31 novel) which are ranging from 1.6% (1/62) to 72.6% (45/62). The A2147 G (aka A2143 G) seems to be associated with a low eradication rate - 40% (2/5) failure while 13.3% (6/45) on treatment success cases, supports its role as clinically significant point mutations. A debatable T2186C (aka T2182C) was found 71.1% (32/45) and 80% (4/5) respectively in both success and failure eradication cases, and suggest the mutation is clinical insignificant. The eradication success rate in patients with novel T2929C mutation was decreased 3 times (7%, 3/45) compared to failure rate (20%, 1/5), suggesting it may play important roles in clarithromycin resistance and warrants further study. CONCLUSION Our studies identified multiple known and novel mutations of 23S rRNA domain V through direct sequencing. Molecular detection of clarithromycin resistance directly on biopsies offers an alternative from of conventional susceptibility test.