Journal of Antimicrobial Chemotherapy (1999) 43, Suppl. C, 21-26
© 1999 The British Society for Antimicrobial Chemotherapy
In-vitro activity of levofloxacin, a new fluoroquinolone: evaluation against Haemophilus influenzae and Moraxella catarrhalis
Fondation Hôpital Saint Joseph, 185 rue Raymond Losserand, 75674 Paris Cédex 14, France
The in-vitro activity of levofloxacin was studied against 10 ß-lactamase-negative and 93 ß-lactamase-positive Moraxella catarrhalis isolates, and 65 ß-lactamase-negative and 35 ß-lactamase-positive Haemophilus influenzae isolates. The MICs of levofloxacin were determined by agar dilution on Mueller–Hinton agar (with the addition of 5% horse blood for M. catarrhalis) or on Haemophilus Test Medium for H. influenzae, and were compared with those of ofloxacin, ciprofloxacin and sparfloxacin, as well as pefloxacin and D-ofloxacin for M. catarrhalis. The fluoroquinolones showed similar activity against isolates of H. influenzae and M. catarrhalis, irrespective of ß-lactamase production. Levofloxacin (MIC 50/90 0.06 mg/L) was 64 times more active against M. catarrhalis than D-ofloxacin (MIC 50/90 4/8 mg/L) and twice as active as ofloxacin (MIC 50/90 0.125 mg/L). Ciprofloxacin had an MIC 50/90 of 0.03/0.06 mg/L and sparfloxacin showed an MIC 50/90 of 0.015 mg/L against M. catarrhalis irrespective of the resistance phenotype of the isolates. Against H. influenzae, levofloxacin was twice as active as ofloxacin (MIC 90 values 0.03 mg/L versus 0.06 mg/L), while the MIC 90s of ciprofloxacin and sparfloxacin were both 0.015 mg/L. Our results therefore suggest that levofloxacin has potential for treating respiratory tract infections caused by H. influenzae and M. catarrhalis.
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