Comparison of Modified Broth Microdilution Method, E test, and Disk Diffusion Method for Antimicrobial Susceptibility Testing of Helicobacter pylori / 대한임상병리학회지

ABSTRACT

BACKGROUND: The emergence of metronidazole (MTZ) resistance among Helicobacter pylori (H. pylori) isolates has compromised the efficacy of the triple therapy. Therefore, special attention should be given toward reliable methods for determining the in vitro susceptibility. But susceptibility testing of H. pylori is not yet either standardized or routinely performed. The purpose of this study was to establish more reliable, but simple to perform and cost-effective antimicrobial susceptibility testing method. METHODS: With 135 clinical isolates of H. pylori, antimicrobial susceptibility tests for MTZ and clarithromycin (CLR) were performed by antibiotic gradient method (E test, AB BIODISK, Sweden) and disk diffusion method (disk method), and the results were compared with the reference modified broth microdilution method (broth method). RESULTS: Resistant rates of Korean isolates of H. pylori for MTZ and CLR were 46.2% and 2.2%, respectively. There was 100% agreements between the E test, disk method and the broth method for CLR. For MTZ, however, agreements between the results obtained by the three methods were variable. Between the E test and broth method, the agreements were 85.1% in terms of susceptibility categories, 80.5% between the disk and broth method, and 93.1% between the E test and disk method. CONCLUSIONS: Routine susceptibility testing of H. pylori to MTZ seems to be required in Korea. The broth method is recommended for MTZ until more accurate, simple and practical alternative method become available. For the CLR, the disk method is recommended, because it is reliable, simple, and economical.