In-vitro activity of levofloxacin, a new fluoroquinolone: evaluation against Haemophilus influenzae and Moraxella catarrhalis.
The in-vitro activity of levofloxacin was studied against 10 beta-lactamase-negative and 93 beta-lactamase-positive Moraxella catarrhalis isolates, and 65 beta-lactamase-negative and 35 beta-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 beta-lactamase production. Levofloxacin (MIC50/90 0.06 mg/L) was 64 times more active against M. catarrhalis than D-ofloxacin (MIC50/90 4/8 mg/L) and twice as active as ofloxacin (MIC50/90 0.125 mg/L). Ciprofloxacin had an MIC50/90 of 0.03/0.06 mg/L and sparfloxacin showed an MIC50/90 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 (MIC90 values 0.03 mg/L versus 0.06 mg/L), while the MIC90s 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.
Kitzis
M D
MD
Fondation Hôpital Saint Joseph, Paris, France.
Goldstein
F W
FW
Miegi
M
M
Acar
J F
JF
D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D024841:Fluoroquinolones; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D064704:Levofloxacin; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects* / Q000201:enzymology; D015242:Ofloxacin / Q000494:pharmacology*; D015366:Pefloxacin / Q000494:pharmacology; D001618:beta-Lactamases / Q000378:metabolism
D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D015366:Pefloxacin; D002939:Ciprofloxacin; D064704:Levofloxacin; D015242:Ofloxacin; D001618:beta-Lactamases; C061363:sparfloxacin