[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.