The comparative in-vitro activity of pefloxacin

The in-vitro antibacterial activities of pefloxacin, other 4-quinolones and representative beta-lactams and aminoglycosides were assessed by determination of minimum inhibitory concentrations (MICs). Pefloxacin (MICs mostly 0.03-2 mg/l) was highly active against Enterobacteriaceae. Gentamicin had slightly lower activity, and ceftazidime and norfloxacin similar activities to pefloxacin whereas ciprofloxacin was more active. Pefloxacin (MICs 0.03-2 mg/l) was active against Acinetobacter but again ciprofloxacin was more active. Aeromonas was highly susceptible to pefloxacin and norfloxacin (MICs 0.008-0.03 mg/l) as well as to ciprofloxacin (MICs 0.001-0.008 mg/l). Pefloxacin (MICs 1-8 mg/l) had similar activities to ceftazidime and gentamicin against Pseudomonas aeruginosa but tobramycin (MICs 0.25-32 mg/l), norfloxacin (MICs 0.25-4 mg/l) and ciprofloxacin (MICs 0.06-1 mg/l) were generally more active. Haemophilus influenzae was susceptible to pefloxacin (MICs 0.008-0.06 mg/l) and to norfloxacin and ciprofloxacin, all of which were more active than ampicillin or ceftazidime. Gardnerella vaginalis was not very susceptible to pefloxacin (MICs 2-8 mg/l), the other 4-quinolones or gentamicin but ampicillin and ceftazidime were highly active. Neisseria gonorrhoeae was very susceptible to pefloxacin and norfloxacin (MICs 0.016-0.12 mg/l) and ciprofloxacin (MICs 0.002-0.008 mg/l). The activity of pefloxacin (MICs 0.25-1 mg/l) was similar to that of ciprofloxacin (MICs 0.12-2 mg/l) but greater than that of norfloxacin (MICs 0.5-4 mg/l) against Staphylococcus aureus. Vancomycin (MICs 1-2 mg/l) had similar activity in vitro but whilst gentamicin was highly active against some isolates, others were resistant. Pefloxacin (MICs mostly 4-32 mg/l) and the other 4-quinolones had lower activity against streptococci (including alpha-, beta-, and non-haemolytic strains, enterococci and pneumococci) than against staphylococci. Benzylpenicillin (or ampicillin in the case of enterococci) were usually more active than any of the 4-quinolones. Bacteroides species, both of the fragilis and melaninogenicus/oralis groups were generally moderately resistant to pefloxacin (MICs 2-32 mg/l) and norfloxacin though ciprofloxacin was more active. Whilst the activity of pefloxacin and the other 4-quinolones was generally somewhat higher against the other anaerobes, ampicillin generally had greater activity.