Critical appraisal of E test for the detection of fluoroquinolone resistance.
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.
Jones
R N
RN
Department of Pathology, University of Iowa College of Medicine, Iowa City 52242, USA.
Erwin
M E
ME
Croco
J L
JL
D000890:Anti-Infective Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003627:Data Interpretation, Statistical; D004352:Drug Resistance, Microbial; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests / Q000379:methods*; D015203:Reproducibility of Results
D000890:Anti-Infective Agents; D024841:Fluoroquinolones