title: Comparison of E-test and disk diffusion assay to evaluate resistance of Helicobacter pylori isolates to amoxicillin, clarithromycin, metronidazole and tetracycline in Costa Rica.
abstract: MIC distribution and susceptibility to four antimicrobial agents were determined by E-test for 94 Helicobacter pylori isolates from Costa Rica. Disk diffusion was evaluated as an alternative method to determine susceptibility and compared with the E-test results by linear regression analysis and an error-rate bounded method. Thirty-eight (40.4%) of the isolates were resistant to metronidazole, 5.3% to clarithromycin and 5.3% to amoxicillin. No isolate was resistant to tetracycline. Multiple resistance was found in 4.3% of the isolates. H. pylori isolates were categorised as resistant to amoxicillin, clarithromycin and tetracycline when inhibition diameters were less than 25, 21 and 25 mm, respectively, in the disk diffusion assay. A breakpoint diameter for metronidazole with disk diffusion could not be firmly established.
authors.affiliation: Facultad de Microbiología, Centro de Investigación en Enfermedades Tropicales, Universidad de Costa Rica, 2060 Ciudad Universitaria Rodrigo Facio, San José, Costa Rica.
authors.forename: Lore
authors.initials: L
authors.lastname: Lang
authors.forename: Fernando
authors.initials: F
authors.lastname: García
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017291:Clarithromycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D016480:Helicobacter pylori / Q000187:drug effects*; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D008795:Metronidazole; D000658:Amoxicillin; D013752:Tetracycline; D017291:Clarithromycin