title: Levofloxacin susceptibility testing for Helicobacter pylori in China: comparison of E-test and disk diffusion method.
abstract: BACKGROUND
  The aims of this study were to compare disk diffusion with E-test method for levofloxacin susceptibility testing of Helicobacter pylori and standardized breakpoints for disk diffusion as a stable and reliable method for determining qualitative levofloxacin susceptibility.
  
  
  METHODS
  We determined the levofloxacin susceptibility of 45 H. pylori strains isolated from Chinese patients by the E-test method. Disk diffusion was evaluated as an alternative method to determine susceptibility and compared with the E-test results by linear regression analysis.
  
  
  RESULTS
  The minimum inhibitory concentration (MIC) values tested by E-test method ranged from 0.047 to 32 μg/mL. Resistance to levofloxacin was detected in 16 (35.6%) isolates. The levofloxacin disk zone sizes obtained by disk diffusion method correlated well (r² = .877) with the MICs obtained by E-test method. As a consequence of regression analysis, isolates with inhibition diameters < 12 mm were considered resistant to levofloxacin. There was 100% agreement between the two methods for levofloxacin, applying the regression-based breakpoints.
  
  
  CONCLUSIONS
  The disk diffusion method is equivalent to the E-test method for testing levofloxacin susceptibility of H. pylori strains; it is more practical and inexpensive, and it is suitable for the analysis of a small number of isolates compared with the E-test method.
authors: Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
authors: Chaohui
authors: C
authors: Yu
authors: Lan
authors: L
authors: Li
authors: Wenguo
authors: W
authors: Chen
authors: Yangwen
authors: Y
authors: Jiao
authors: Ningmin
authors: N
authors: Yang
authors: En
authors: E
authors: Yang
authors: Jianzhong
authors: J
authors: Zhang
authors: Lihua
authors: L
authors: Chen
authors: Youming
authors: Y
authors: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D005260:Female; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D064704:Levofloxacin; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015242:Ofloxacin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D064704:Levofloxacin; D015242:Ofloxacin