Comparative activity of new quinolones against 326 clinical isolates of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an important emerging pathogen causing a va riety of infections in severely ill patients. This microorganism is inheren tly resistant to many antibiotics, and only a few therapeutic options are a vailable. The principal aim of this study was to assess the in vitro activi ty of new quinolones against this pathogen. Three hundred and twenty-six si ngle clinical isolates were tested in this study. The MIC90 was 16 mg/L for ciprofloxacin, 8 mg/L for levofloxacin and gatifloxacin, 4 mg/L for trovaf loxacin, moxifloxacin and sparfloxacin and 2 mg/L for clinafloxacin. At a 2 mg/L concentration, a C-max lung:MIC ratio of greater than or equal to 10 can be reached for 95%, 84.3%, 83.1% and 81.5% of isolates, respectively, f or clinafloxacin, trovafloxacin, moxifloxacin and sparfloxacin (P < 0.001 c ompared with levofloxacin and ciprofloxacin). In spite of the rare but seri ous adverse events associated with the new-generation quinolones, these age nts may become very useful in the treatment of certain severe or life-threa tening infectious conditions due to S. maltophilia, notably lower respirato ry tract infections.