[In vitro activity of sparfloxacin against methicillin-resistant staphylococci]

The antimicrobial activity of sparfloxacin (CAS 110871-86-8) against 154 clinical isolates of methicillin-resistant staphylococci was investigated and compared with that of 6 other fluoroquinolones. The isolates consisted of 100 methicillin-resistant Staphylococcus aureus (MRSA), 29 Staphylococcus epidermidis (MRSE) and 25 other coagulase-negative staphylococci (CNS). Sparfloxacin was more active than ciprofloxacin and the other fluoroquinolones against all strains tested. The MIC90 of sparfloxacin against the 100 isolates of Staphylococcus aureus was 8 mg/l, while that of ciprofloxacin was > or = 64 mg/l. Moreover, ciprofloxacin-susceptible MRSA isolates were inhibited by sparfloxacin at a concentration of < or = 0.06 mg/l. The other quinolones had an MIC90 ranging from 0.5 mg/l to 4 mg/l against ciprofloxacin-susceptible MRSA. Similar results were obtained for the MRSE and CNS isolates tested. As many as 90% of the ciprofloxacin-susceptible microorganisms were inhibited at a concentration of < or = 0.06 mg/l or 0.125 mg/l of sparfloxacin. The MIC90 of sparfloxacin against ciprofloxacin-resistant CNS and MRSE were 4 mg/l and 8 mg/l, respectively. Sparfloxacin was clearly more active than any of the other quinolones against all species tested, although higher concentrations were needed to inhibit ciprofloxacin-resistant staphylococci.