Tentative criteria for confirming the in vitro susceptibilities of Haemophilus influenzae and Neisseria gonorrhoeae to two fluoroquinolones (sparfloxacin and levofloxacin), including quality control parameters

A. L. Barry, P. C. Fuchs, S. D. Allen, J. H. Jorgensen, F. C. Tenover, P. R. Murray, D. J. Hardy, C. N. Baker

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Abstract

Sparfloxacin and levofloxacin were evaluated against 150 Haemophilus influenzae isolates and 149 Neisseria gonorrhoeae isolates in order to define susceptibility testing parameters. Sparfloxacin-susceptible H. influenzae strains were defined as those for which the MICs were ≤0.25 μg/ml and the zones were ≥30 mm, and N. gonorrhoeae susceptible strains were those for which the MICs were ≤0.03 μg/ml and the zones were ≥39 mm (5-μg disks). Levofloxacin-susceptible strains of H. influenzae included those for which the MICs were ≤0.12 μg/ml and the zones were ≥32 mm and N. gonorrhoeae susceptible strains were those for which the MICs were ≤0.12 μg/ml and the zones were ≥37 mm (5-μg disks). Criteria for a resistant category cannot yet be defined for either quinolone. In multilaboratory studies with different lots of Haemophilus Test Medium, replicate tests with the standard control strain of H. influenzae (ATCC 49247) were evaluated. For sparfloxacin disk tests, the proposed zone size limits were 33 to 42 mm and broth microdilution MIC limits were 0.004 to 0.016 μg/ml, whereas for levofloxacin tests, zone size limits were 33 to 41 mm and broth microdilution MIC limits were 0.008 to 0.03 μg/ml. Other multilaboratory studies evaluated tests with supplemented GC agar and N. gonorrhoeae ATCC 49226; for both drugs, zone size limits were 44 to 52 mm and agar dilution MIC limits were 0.004 to 0.016 μg/ml.

Original languageEnglish (US)
Pages (from-to)2375-2380
Number of pages6
JournalJournal of clinical microbiology
Volume31
Issue number9
Publication statusPublished - Jan 1 1993

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ASJC Scopus subject areas

  • Microbiology (medical)

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