In vitro Activities of Ciprofloxacin, Ofloxacin, Norfloxacin and Rosoxacin Compared with Cinoxacin and Trimethoprim

Abstract
The in vitro activities of ciprofloxacin, ofloxacin, norfloxacin, rosoxacin, cinoxacin and trimethoprim have been compared. An agar dilution method has been employed for the measurement of minimal inhibitory concentrations (MICs). 426 clinical, bacterial urinary isolates mainly from hospitalised patients were included; all common urinary tract pathogens were represented. The newer quinolones were highly active against Enterobacteriaceae species, Pseudomonas aeruginosa and Acinetobacter calco-aceticus. Ciprofloxacin was the most active agent against these organisms (MICs < 2 mg/1). A few strains of Escherichia coli and Klebsiella were resistant to rosoxacin (MIC < 128 mg/1). Cinoxacin and trimethoprim were considerably less active against gram-negative strains. The new quinolones were also active against staphylococci of various species and enterococci (MICs < 4 mg/1) except for rosoxacin for which 16 mg/1 was needed to inhibit all gram-positive isolates. Cinoxacin was virtually inactive against this group whereas trimethoprim showed variable activity.