Activity of pefloxacin and thirteen other antimicrobial agents in vitro against isolates from hospital and genitourinary infections.

The in-vitro activity of the quinolone derivative pefloxacin was compared with that of three other quinolones, five beta-lactam antibiotics and three aminoglycosides against 367 isolates from hospital patients and from out-patients with genitourinary infections. MIC90 of pefloxacin and norfloxacin for each strain was the same; that of ciprofloxacin was a little lower. All strains except Escherichia coli were resistant to nalidixic acid. Pefloxacin was highly active against Staphylococcus aureus (39 strains; MIC90 1.0 mg/l) and most strains of coagulase-negative staphylococci (56; 4 mg/l), Esch. coli (50; 0.25 mg/l), other enterobacteria (33; 1.0 mg/l) and Pseudomonas aeruginosa 6; 0.25 mg/l). With Bacteroides spp. (total 78; 64 mg/l), the fragilis group (23) and the fusobacteria (19) were resistant, but the melaninogenicus-oralis group (31; range 0.06- greater than 64 mg/l) and B. ureolyticus (22; 0.125- greater than 64 mg/l) gave variable results. Amongst genitourinary isolates, Neisseria gonorrhoeae (15) and Haemophilus ducreyi (34) were sensitive (less than 0.06 mg/l) but Gardnerella vaginalis (25) and Mobiluncus spp. (11) were resistant (32 mg/l). Pefloxacin was more active than ceftazidime, cefotaxime, ceftizoxime, latamoxef and piperacillin against S. aureus and coagulase-negative staphylococci and than gentamicin, tobramycin and amikacin against coagulase-negative staphylococci. No enterobacteria or pseudomonads were resistant to pefloxacin or other quinolones, whereas some were resistant to beta-lactams and aminoglycosides.