In vitro antimicrobial activity of sparfloxacin (AT-4140, CI-978, PD 131501) compared with numerous other quinolone compounds

Abstract

Sparfloxacin (AT-4140, CI-978, PD 131501) was tested against over 800 recent bacteremic strains and compared with ciprofloxacin and six other fluoroquinolones. The 90% minimum inhibitory concentration (MIC 90) ranges for the Enterobacteriaceae species were (a) sparfloxacin, 0.03–1 μg/ml and (b) ciprofloxacin, 0.015–0.25 μg/ml. Moraxella catarrhalis, Haemophilus influenzae, and Neisseria gonorrhoeae were very susceptible to sparfloxacin (MIC 90s, 0.004–⩽0.03 μg/ml) and the other comparison drugs. Staphylococcus aureas and other staphylococci were generally susceptible to the tested fluoroquinolones but very susceptible to sparfloxacin and WIN 57273. All β-hemolytic streptococci, enterococci, and pneumococci had sparfloxacin MICs of ⩽1 μg/ml. Sparfloxacin was quite active against anaerobic bacteria including Bacteroides fragilis gr. and Gram-positive strains (MIC 90s, ⩽2 μg/ml). The most resistant enteric bacilli were among Serratia marcescens and the Proteae, especially the Providencia spp. (two- to eightfold higher MICs). Pseudomonas aeruginosa strains were also susceptible to sparfloxacin (MIC 90, 2 μg/ml). Magnesium ions, CO 2 incubation, and low pH had some adverse effect on sparfloxacin MICs, and resistance development was documented among current clinical isolates of staphylococci, pseudomonas, and some enteric species.