Vakil N, McSorley DJ, Hahn BA. Clarithromycin-resistant helicobacter pylori in patients with duodenal ulcer in the United States. Am J Gastroenterol. 1998 Sep;93(9):1432-5.

BACKGROUND: Clarithromycin is a key component of several antimicrobial treatment regimens for Helicobacter 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 for H. pylori and 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 of H. pylori. In 1995–96, 44 of 348 patients (12.6%; p= 0.025) had resistant strains of H. pylori. Patients who had previously failed antimicrobial treatment for H. pylori accounted for much of the increase in resistant strains (25%).

CONCLUSIONS: Failed therapy with clarithromycin-based regimens is a growing cause of antimicrobial resistance in H. pylori in 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.

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