Activity of moxifloxacin and other quinolones against pneumococci resistant to first-line agents, or with high-level ciprofloxacin resistance

The activity of moxifloxacin and other quinolones was assessed against 288 epidemiologically diverse isolates of Streptococcus pneumoniae, many of the m resistant to one or more first-line agents and/or with increased ciproflo xacin resistance (minimum inhibitory concentrations, MICs 16- > 64 mg/l com pared with 1-2 mg/l for most isolates). Moxifloxacin and grepafloxacin were the most active quinolone analogues, inhibiting about 90% of the isolates at less than or equal to 1 mg/l, whereas levofloxacin inhibited 64% of isol ates at less than or equal to 1 mg/l and ciprofloxacin inhibited 42%. Moxif loxacin also was the most active agent against isolates with elevated cipro floxacin resistance (MIC 16- > 64 mg/l): moxifloxacin MICs of around 4 mg/l were seen for most such isolates, compared with 16-32 mg for levofloxacin and grepafloxacin. The activity of moxifloxacin against pneumococci resista nt to one or more first-line agent suggests it will have a useful therapeut ic role, although its activity against highly ciprofloxacin resistant isola tes seems marginal. (C) 2001 Elsevier Science B.V. and International Societ y of Chemotherapy. All rights reserved.