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Background: Clarithromycin is a key component of several antimicrobial treatment regimens forHelicobacter pylori. Cure rates with clarithromycin-containing regimens are significantly decreased when resistance is present. Resistance develops by a point mutation in the ribosomal RNA of some organisms exposed to clarithromycin. We studied the prevalence of clarithromycin-resistant organisms in patients with duodenal ulcer in the United States from 1993–96. Methods: Patients with endoscopic evidence of a duodenal ulcer were studied. Gastric biopsies were cultured forH. pyloriand antimicrobial sensitivity was determined by the E-test (epsilometer agar diffusion gradient). Results: In 1993–94, three of 78 patients (4%) had clarithromycin-resistant strains ofH. pylori. In 1995–96, 44 of 348 patients (12.6%;p= 0.025) had resistant strains ofH. pylori. Patients who had previously failed antimicrobial treatment forH. pyloriaccounted for much of the increase in resistant strains (25%). Conclusions: Failed therapy with clarithromycin-based regimens is a growing cause of antimicrobial resistance inH. pyloriin the United States. Whereas the overall rates of primary resistance are low, the increase in secondary resistance over a short period of time is worrisome. New treatments that prevent the emergence of resistance may be important in the future.
N Vakil (Tue,) studied this question.