Comparative in-vitro activity of moxifloxacin, penicillin, ceftriaxone and ciprofloxacin against pneumococci isolated from meningitis

Minimum inhibitory concentrations of penicillin, ceftriaxone, ciprofloxacin, and moxifloxacin (BAY 12-8039), a new 8-methoxyquinolone, were determined for 60 cerebrospinal fluid isolates of Streptococcus pneumoniae collected during January 1997-April 1998 at Italian medical centres. Three reference isolates with predetermined MIC values (two penicillin- and multidrug-resistant isolates, one uniformly susceptible to all antibiotics) were also tested with the same antibiotics. The MIC90 of penicillin was less than or equal to 0.03 mg/L (range less than or equal to 0.03-2 mg/L), of ceftriaxone 0.06 mg/L (range less than or equal to 0.03-0.5 mg/L), of ciprofloxacin 2 mg/L (range 0.5-8 mg/L) and of moxifloxacin 0.06 mg/L (range 0.03-0.12 mg/L). Moxifloxacin was effective against all the penicillin-resistant isolates tested, with an MIC of 0.06 mg/L. Moxifloxacin was 32-fold more active than ciprofloxacin and was not affected by penicillin and cephalosporin resistance. These results indicate that moxifloxacin could be useful for the treatment of both penicillin-sensitive and -resistant S. pneumoniae meningitis.