IN-VITRO AND IN-VIVO ACTIVITIES OF CLINAFLOXACIN, CI-990 (PD-131112),AND PD-138312 VERSUS ENTEROCOCCI

Certain new fluoroquinolones have high activity against enterococci. A gainst Enterococcus faecalis (n = 18), MICs at which 90% of the isolat es were inhibited were as follows (in micrograms per milliliter): clin afloxacin, 0.125; CI-990, 0.5; and PD 138312, 0.25 (compared with 1 mu g/ml for ciprofloxacin and 2 mu g/ml for ofloxacin). Strains producin g beta-lactamase or that were vancomycin resistant or resistant to hig h-level gentamicin were not quinolone cross-resistant. The drugs were bactericidal and were unaffected by 50% human serum. Oral efficacies ( in milligrams per kilogram of body weight for 50% protective doses) in lethal mouse infections with quinolone-susceptible strains were 4.3 t o 24 for clinafloxacin, 7.2 to 39 for CI-990, 7.2 to 76 for PD 138312, and 41 to >100 for ciprofloxacin; when the drugs were given subcutane ously, the order was similar and values ranged from 1.1 to 12.5. Clina floxacin, CI-990, and PD 138312 may have therapeutic potential in syst emic enterococcal infections in humans.