Activity of ciprofloxacin against resistant clinical isolates.

The in-vitro activity of ciprofloxacin, a new quinolone derivative, was determined by broth microdilution for 518 clinical isolates. The MICs for 90% of the organisms were 2 mg/l for Pseudomonas aeruginosa, 8 mg/l for P. maltophilia, 4 mg/l for other Pseudomonas spp., 1 mg/l for Acinetobacter anitratus, 0.03-0.5 mg/l for differing species of Enterobacteriaceae, 2 mg/l for Streptococcus faecalis, 0.25 mg/l for coagulase-negative Staphylococcus spp. and 2 mg/l for S. aureus. Furthermore, on a weight basis, the activity of ciprofloxacin was equivalent or superior to that of cefotaxime, ceftazidime, gentamicin, imipenem, latamoxef, piperacillin, oxacillin and vancomycin. In general, ciprofloxacin appears to be highly active against organisms resistant to many broad spectrum antimicrobials, including norfloxacin, gentamicin, cefotaxime, and ceftazidime, with MICs for 90% of organisms in the range of 0.03 to 16 mg/l.