ANTIBIOTIC SUSCEPTIBILITIES OF HELICOBACTER-PYLORI STRAINS ISOLATED IN THE PROVINCE OF ALBERTA

The incidence of antibiotic resistance to amoxicillin, clarithromycin, erythromycin, metronidazole and tetracycline in Helicobacter pylori s trains isolated from gastric biopsy specimens obtained in Alberta was in vestigated. Results for all antibiotics were obtained using agar di lution, and in addition to metronidazole, the E test was used. Resista nce to amoxicillin and tetracycline was not detected. Metronidazole re sistance determined using agar dilution was approximately 12% (95% CI 4% to 26%) when minimal inhibitory concentrations (MICs) were at least 8 mu g/mL, but fell to 2% (95% CI 0.1% to 13%) when MICs were set at 32 mu g/mL or greater. The E test for metronidazole resistance (MIC 8 mu g/mL or greater) yielded a slightly higher percentage of resistant strains compared with agar dilution tests (14%, 95% CI 5% to 29%). One of the 31 strains was resistant to clarithromycin (MIC 8 mu g/mL) and erythromycin (MIC 16 mu g/mL). Thus, the incidence of resistance to c larithromycin, part of the currently used triple therapy for eradicati on of H pylori, was 3% (95% CI 0.1% to 17%).