HELICOBACTER-PYLORI - PRIMARY SUSCEPTIBILITY TO CLARITHROMYCIN IN-VITRO IN NOVA-SCOTIA

Resistance to antimicrobial agents is a major determinant of the effic acy of regimens to eradicate Helicobacter pylori. Clarithromycin (CLA) has become one of the most commonly used antibiotics for treatment of H pylori infection. In this study, the rate of primary resistance to CLA in H pylori isolated from patients was determined. One hundred six ty-two strains were recovered from patients before treatment. Strains were grown and inoculated onto Mueller-Hinton agar with 7% sheep blood . CLA epsilometer gradient agar diffusion test (E test) strips were us ed to test for susceptibility. Appropriate control organisms were test ed to validate the assay. Plates were incubated at 37 degrees C in a m icroaerophilic atmosphere for up to five days. E test results were eas y to interpret. Strains were considered resistant if the minimum inhib itory concentration (MIC) was 2 mu g/mL or greater. Three strains were resistant (two strains with MIC 8 mu g/mL and one strain with MIC 12 mu g/mL), and 159 strains were sensitive (MICs ranged from less than 0 .016 to 0.38 mu g/mL). Ninety percent of the strains had MICs of 0.023 mu g/mL. Primary resistance was 1.8%. These susceptibility data suppo rt the use of CLA for the treatment of H pylori in the Nova Scotia pop ulation.