Helicobacter pylori resistance to metronidazole and clarythromicin:: descriptive analysis 1997-2000

BACKGROUND AND OBJECTIVE: We aimed to assess the resistance of H. pylori to clarithromycin and metronidazole, in patients with and without previous eradication treatment, in a geographic area from the north of Spain. We also analyzed the evolution of resistance rates and its relationships with annual antibiotic consumption. PATIENTS AND METHOD: Retrospective study including all patients with H. pylori infection and Positive culture from January 1997 to December 2000. Minimal inhibitory concentrations (MIC) determined by the E test were used to report the clarithromycin (MIC > 2 mg/l) and metronidazole (MIC > 32 mg/l) resistance. RESULTS: A total of 537 clinical H. pylori isolates from patients without (n = 389) and with previous eradication treatment (n = 148) were studied. H. pylori resistance to clarithromycin and metronidazole was found in 8.7% (95% CI, 6.1-12) and 13.8% (95% CI, 10.4-17.3) patients without previous eradication treatment and in 39.2% (95% CI, 31.3-47.1) and 37.8% (95% CI, 30-45.7) patients with previous eradication treatment (p < 0.001), respectively. Clarithromycin resistance remained stable (1997: 9.7%; 1998: 5.7%; 1999: 11.8%; 2000: 6.2%) whereas metronidazole resistance decreased over the 4 years study period (1997: 38.7%; 1998: 15.1%; 1999: 9%; 2000: 6.9%). We did not observe any clear relationship between resistance's evolution and antibiotic annual consumption. CONCLUSIONS: In our geographic area, primary resistance rates for clarithromycin remained stable whereas resistance for metronidazole decreased over the 4 years period.