Critical appraisal of E test for the detection of fluoroquinolone resistance.

  • Jones R
  • Erwin M
  • Croco J
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The ability of E test to accurately detect fluoroquinolone resistance was compared with an agar dilution reference method. Nearly 300 isolates belonging to 26 different species (62.5% with documented ciprofloxacin resistance) were tested with ciprofloxacin, fleroxacin, levofloxacin, norfloxacin, ofloxacin, and sparfloxacin. In contrast to earlier reports, E test MIC values for pneumococci and all rapid growing aerobes were routinely higher (approximately 0.5 log2 dilution step) than agar dilution results. The E test stable-gradient method also efficiently identified fluoroquinolone-resistant subpopulations which were not detected by the reference procedure with the standard inoculum. Categorical agreement for 1710 test comparisons was approximately 90% with no very major, false-susceptible errors. We found the E test to be a valid, reproducible method for fluoroquinolone susceptibility testing that provided quantitative results and produced a conservative (1.6% false-resistant results) assessment of susceptibility of bacteria including isolates of Streptococcus pneumoniae and Pseudomonas aeruginosa to compounds in this antimicrobial class.

Author-supplied keywords

  • Anti-Infective Agents
  • Anti-Infective Agents: pharmacology
  • Colony Count
  • Data Interpretation
  • Drug Resistance
  • Fluoroquinolones
  • Microbial
  • Microbial Sensitivity Tests
  • Microbial Sensitivity Tests: methods
  • Reproducibility of Results
  • Statistical

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  • R N Jones

  • M E Erwin

  • J L Croco

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