Primary Clarithromycin Resistance in Helicobacter pylori: the Multicentric Italian Clarithromycin Resistance Observational (MICRO) Study

BACKGROUND: Primary clarithromycin resistance markedly reduces Helicobacter pylori eradication rate following standard therapies. Prevalence of primary clarithromycin resistance in H. pylori is increasing, and three point mutations are mainly involved. AIM. To assess both the prevalence of primary clarithromycin resistance in Italy, and the distribution of the involved point mutations. METHODS: Primary clarithromycin resistance was assessed by TaqMan real-time polymerase chain reaction on antral biopsies of 253 consecutive, H. pylori infected patients enrolled in 13 Italian centres between January and September 2010. RESULTS: Primary clarithromycin resistance was detected in 25 (9.9%) patients, with prevalence values widely ranging from 0 to 25%. Clarithromycin resistance rate was higher in female as compared to male patients (13.4% vs. 5.3%, p=0.03), and it tended to be higher in non-ulcer dyspepsia than in peptic ulcer patients (10.6% vs. 6.9%, p=0.5), female patients with non-ulcer dyspepsia showing the highest value (15.4%). The A2143G point mutation was detected in 13 (52.0%) patients, the A2142G in 9 (34.6%), whilst a double point mutation (A2143G plus A2142G) in 3 (11.6%) cases. CONCLUSIONS: Primary clarithromycin resistance is highly variable in different Italian geographic areas. High resistance rates were observed in female and in dyspeptic patients. Among the three point mutations of clarithromycin resistance, the A2143G remains the most frequently observed.