In vitro activity of clinafloxacin in comparison with other quinolones against Stenotrophomonas maltophilia clinical isolates in the presence and absence of reserpine

A total of 33 Stenotrophomonas maltophilia clinical isolates were tested for their susceptibility to clinafloxacin in comparison with ciprofloxacin, levofloxacin, moxifloxacin, nalidixic acid, norfloxacin, sparfloxacin and trovafloxacin. The MIC50 and MIC90 were as follows: ciprofloxacin 4 and 64 mug/mL clinafoxacin 0.5 and 4 mug/mL; levofloxacin 2 and 32 mug/mL; moxifloxacin I and 8 mug/mL; nalidixic acid 8 and 128 mug/mL; norfloxucin 64 and 256 mug/mL, sparfloxacin I and 16 mug/mL; and trovafloxacin I and 8 mug/mL. Clinafloxacin was the most active quinolone, with only a 15.1% of strains showing resistance. When the MICs were determined in the presence of 25 mug/ml of reserpine, the MIC90 of trovafloxacin and moxifloxacin did not change, whereas decreased 2-fold for clinafloxacin, levofloxacin, sparfloxacin and nalidixic acid, and 4- and 8-fold for ciprofloxacin and norfloxacin respectively. No clinafloxacin-resistant strains were observed when the MIC was performed in the presence of reserpine. Therefore, clinafloxacin shows the better in vitro activity against these 33 strains of S. maltophilia. (C) 2002 Elsevier Science Inc. All rights reserved.