caa a22 4500 397592868 CHVBK 20180308164943.0 cr unu---uuuuu 161202e199603 xx s 000 0 eng 10.1093/jac/37.3.473 doi (NATIONALLICENCE)oxford-10.1093/jac/37.3.473 Clarithromycin resistance in Helicobacter pylori: prevalence in untreated dyspeptic patients and stability in vitro [Elektronische Daten] [Hua-Xiang Xia, Martin Buckley, Conor T. Keane, Colm A. O'Morain] Susceptibilities to clarithromycin and metronidazole of 444 Helicobacter pylori isolates cultured from antral biopsies of 444 dyspeptic patients were determined by disc diffusion tests (15 μg disc for clarithromycin, 5 μg disc for metronidazole). Susceptibility of 46 of these isolates to erythromycin (5 μg disc) was also tested. Minimal inhibitory concentrations (MICs) of clarithromycin for 42 selected isolates were determined by a plate dilution method. A zone diameter of 30 mm was defined as a ‘cut-off' size differentiating susceptibility and resistance of the organism to clarithromycin, by comparing results obtained with the two methods. Of the 444 isolates, 424 (95.5%) were highly sensitive to clarithromycin, with zone diameters ranging from 30 to 98 mm. Twenty isolates (4.5%) were defined as resistant to clarithromycin, with zone diameters ranging between 6 and 28 mm. The incidence of clarithromycin resistance was similar in men and women and in different age groups, and was not significantly different between patients with peptic ulcer and non-ulcer dyspepsia. Among the 444 isolates, 168 (37.8%) were metronidazole resistant. There was cross resistance between clarithromycin and erythromycin, but not between clarithromycin and metronidazole. Stability of clarithromycin resistance was evaluated by the disc diffusion test and confirmed by the plate dilution method. Among the 20 clarithromycin-resistant isolates, nine (45%) reverted to be sensitive after 2-5 subcultures on drug-free agar. The findings in this study indicate that the incidence of clarithromycin-resistant H. pylori m untreated dyspeptic patients is low. Cross-resistance occurs between macrolides and resistance to clarithromycin in some strains is reversible. © 1996 The British Society for Antimicrobial Chemotherapy Original articles nationallicence Xia Hua-Xiang Department of Clinical Microbiology, CPL, St. James's Hospital Dublin 8, Ireland aut Buckley Martin Department of Gastroenterology, Meath/Adelaide Hospitals Trinity College, Dublin, Ireland aut Keane Conor T. Department of Clinical Microbiology, CPL, St. James's Hospital Dublin 8, Ireland aut O'Morain Colm A. Department of Gastroenterology, Meath/Adelaide Hospitals Trinity College, Dublin, Ireland aut Journal of Antimicrobial Chemotherapy Oxford University Press 37/3(1996-03), 473-481 0305-7453 37:3<473 1996 37 jac https://doi.org/10.1093/jac/37.3.473 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jac/37.3.473 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Xia Hua-Xiang Department of Clinical Microbiology, CPL, St. James's Hospital Dublin 8, Ireland aut NATIONALLICENCE 700 1- Buckley Martin Department of Gastroenterology, Meath/Adelaide Hospitals Trinity College, Dublin, Ireland aut NATIONALLICENCE 700 1- Keane Conor T. Department of Clinical Microbiology, CPL, St. James's Hospital Dublin 8, Ireland aut NATIONALLICENCE 700 1- O'Morain Colm A. Department of Gastroenterology, Meath/Adelaide Hospitals Trinity College, Dublin, Ireland aut NATIONALLICENCE 773 0- Journal of Antimicrobial Chemotherapy Oxford University Press 37/3(1996-03), 473-481 0305-7453 37:3<473 1996 37 jac Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford