Impact of clarithromycin resistance on the effectiveness of a regimen for Helicobacter pylori: a prospective study of 1‐week lansoprazole, amoxycillin and clarithromycin in active peptic ulcer

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Abstract
Background : Clarithromycin is a key antimicrobial in the combinations used to cure Helicobacter pylori infections, so there is a need to define the impact of in vitro resistance on in vivo results. Methods : A prospective trial was designed to study the effectiveness of the 1‐week combination of lansoprazole, clarithromycin and amoxycillin in 102 consecutive patients with active peptic ulcer. The pre‐treatment and post‐treatment sensitivity to amoxycillin, metronidazole and clarithromycin were studied by E‐test, and H. pylori status was defined by histology, culture and urease test at diagnosis and one month after treatment, and by urea‐breath test 2 months after treatment. Results : The eradication rate (intention‐to‐treat analysis) was 77% (95% CI: 69–86). No clinical factor was found to be different between eradicated and non‐eradicated patients. Clarithromycin‐resistant strains were found in 10 (10%; CI: 5–17) patients. The eradication rate was 20% (CI: 3–56) in these patients vs. 83% (CI: 75–91) in patients harbouring clarithromycin‐sensitive strains (P < 0.001). A logistic‐regression analysis confirmed clarithromycin resistance as the only factor associated with treatment failure. Conclusions : Clarithromycin resistance significatively impairs the effectiveness of the combination of lansoprazole, amoxycillin, and clarithromycin. The 80% efficacy goal will be difficult to reach in areas with high (>10%) primary clarithromyicin resistance, if currently recommended proton pump inhibitor‐triple therapies are used.