Interpretive criteria for CI-960, fleroxacin and temafloxacin susceptibility tests withHaemophilus influenzae

Abstract

Haemophilus influenzae strains with varied ampicillin resistance and beta-lactamase production patterns were tested against three investigational fluorinated quinolones (CI-960, fleroxacin, temafloxacin) using Haemophilus Test Medium (HTM) and National Committee for Clinical Laboratory Standards (NCCLS) methods. The disk diffusion zones and MICs were compared and regression statistics and scattergrams generated. The rank order of the agents according to activity againstHaemophilus influenzae was CI-960 (MIC50 0.002 µg/ml) > temafloxacin (MIC50 0.015 µg/ml) > fleroxacin (MIC50 0.03 µg/ml). The recommended susceptibility interpretive criteria for the 5-µg disks of each drug were: for CI-960 ≥ 23 mm (MIC correlate ≤ 1 µg/ml); for fleroxacin ≥ 19 mm (MIC correlate ≤ 2 µg/ml); and for temafloxacin ≥ 16 mm (MIC correlate ≤ 2 µg/ml). All recentHaemophilus influenzae isolates tested were susceptible to these potent fluoroquinolones and no interpretive errors were observed.