Abstract
In vitro and in vivo antibacterial activities of a new quinolone, sparfloxacin (SPFX), were compared with those of ciprofloxacin (CPFX), ofloxacin (OFLX), enoxacin (ENX) and norfloxacin (NFLX) with the following results.
1. SPFX was similar to CPFX in activity against gram-negative bacteria and Legionella spp., and more potent than CPFX, OFLX, ENX and NFLX in activity against gram-positive bacteria, glucose-nonfermenters, anaerobes, Mycoplasma spp., Chlamydia spp., and Mycobacterium spp. Most clinical isolates were as susceptible to SPFX as laboratory strains.
2. SPFX was not cross-resistant with ampicillin, cephalexin, tetracycline, chloramphenicol and streptomycin, and inhibited bacteria highly resistant to nalidixic acid (MIC:≥100μg/ml) in a concentration range of 0.025-0.78μg/ml.
3. The MIC values of SPFX were scarcely affected by the addition of horse serum, sodium desoxycholate or divalent cations such as Mg2+ and Ca2+, but slightly rose when medium pH lowered or inoculum sizes were enlarged. The MICs of SPFX in human urine were no higher than those in sensitivity test broth.
4. SPFX was bactericidal around its MICs.
5. Frequencies of mutants resistant to SPFX were <1.6×10-9 at selective concentrations of 16 times the MICs.
6. SPFX was more effective than CPFX, OFLX, ENX and NFLX by the oral route in systemic, pulmonry, kidney and dermal infections in mice.
These results indicate that SPFX is a quinolone with broad and potent antibacterial activity in vitro and in vivo, and may be useful for various kinds of infections in humans.
