title: Antimicrobial susceptibility testing for Helicobacter pylori isolates from Brazilian children and adolescents: comparing agar dilution, E-test, and disk diffusion.
abstract: Antimicrobial susceptibility testing for Helicobacter pylori is increasingly important due to resistance to the most used antimicrobials agents. Only agar dilution method is approved by CLSI, but it is difficult to perform routinely. We evaluated the reliability of E-test and disk diffusion comparing to agar dilution method on Helicobacter pylori antimicrobial susceptibility testing. Susceptibility testing was performed for amoxicillin, clarithromycin, furazolidone, metronidazole and tetracycline using E-test, disk-diffusion and agar dilution method in 77 consecutive Helicobacter pylori strains from dyspeptic children and adolescents. Resistance rates were: amoxicillin - 10.4%, 9% and 68.8%; clarithromycin - 19.5%, 20.8%, 36.3%; metronidazole - 40.2%33.7%, 38.9%, respectively by agar dilution, E-test and disk diffusion method. Furazolidone and tetracycline showed no resistance rates. Metronidazole presented strong correlation to E-test (r = 0.7992, p < 0.0001) and disk diffusion method (r=-0.6962, p < 0.0001). Clarithromycin presented moderate correlation to E-test (r = 0.6369, p < 0.0001) and disk diffusion method (r=-0.5656, p < 0.0001). Amoxicillin presented weak correlation to E-test (r = 0.3565, p = 0.0015) and disk diffusion (r=-0.3565, p = 0.0015). Tetracycline presented weak correlation with E-test (r = 0.2346, p = 0.04) and furazolidone to disk diffusion (r=-0.0288, p = 0.8038). E-test presented better agreement with gold standard. It is an easy and reliable method for Helicobacter pylori susceptibility testing. Disk diffusion method presented high disagreement and high rates of major errors.
authors.affiliation: Disciplina de Gastroenterologia Pediátrica Hepatologica e Nutrição Escola Paulista de Medicina Universidade Federal de São Paulo São PauloSP Brazil Disciplina de Gastroenterologia Pediátrica, Hepatologica e Nutrição, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Silvio Kazuo
authors.initials: SK
authors.lastname: Ogata
authors.affiliation: Laboratório Especial de Microbiologia Clínica Departamento de Doenças Infecciosas Escola Paulista de Medicina Universidade Federal de São Paulo São PauloSP Brazil Laboratório Especial de Microbiologia Clínica, Departamento de Doenças Infecciosas, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Gales
authors.affiliation: Disciplina de Gastroenterologia Pediátrica Hepatologica e Nutrição Escola Paulista de Medicina Universidade Federal de São Paulo São PauloSP Brazil Disciplina de Gastroenterologia Pediátrica, Hepatologica e Nutrição, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Kawakami
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001938:Brazil; D002648:Child; D024881:Drug Resistance, Bacterial; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents
keywords: E-test; Helicobacter pylori; disk diffusion; susceptibility test