Amifloxacin (Win49375), a synthetic antibacterial agent of the quinolone class, is highly active by the oral route, with 50% effective doses within two- to threefold of those obtained with parenteral medication. When mice infected intraperitoneally with E. coli Vogel are medicated at 0.5-h postinfection subcutaneously, intravenously, or orally the ED50s for Amifloxacin are 0.6, 0.8, and 1.0 mg/kg, respectively[1]. Amifloxacin inhibited Branhamella, Haemophilus, and Neisseria at less than or equal to 0.25 mg/ml, and 90% of Pseudomonas aeruginosa, including gentamicin- and carbenicillin-resistant isolates, at 4 mg/ml. It also inhibited staphylococci, including methicillin-resistant isolates, but was less active against streptococci and Bacteroides species. Amifloxacin had in vitro activity similar to enoxacin, ofloxacin, and norfloxacin, but was less active than ciprofloxacin[2]. Amifloxacin showed potent inhibitory activity against DNA gyrase of Escherichia coli. Cell lysis was induced with combined treatment of amifloxacin and sodium dodecyl sulfate in E. coli. The frequency of mutants spontaneously resistant to amifloxacin was extremely low in all species tested[3]. For amikacin-resistant P aeruginosa, the minimal inhibitory concentrations (MICs) of amifloxacin ranged from 1 to 16 mg/ml. For all strains tested, microbial susceptibilities to amifloxacin were greater than those to currently available oral antimicrobial drugs, such as cinoxacin and trimethoprim[4].
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