In vitro activity of clinafloxacin against fluoroquinolone resistant Spanish clinical isolates

The in vitro activity of clinafloxacin against 162 ciprofloxacin-resistant clinical isolates was determined. Isolates were selected when their MIC to ciprofloxacin was 2 mg/l (intermediate) or >2 mg/l (resistant). The followi ng strains were tested: 61 Escherichia coli, 12 Klebsiella pneumoniae, 7 Pr oteus mirabilis, 21 Serratia marcescens, 4 Enterobacter cloacae, 21 Pseudom onas aeruginosa, 21 Staphylococcus. aureus (resistant to methicillin) and 1 5 Enterococcus spp. Clinafloxacin, ciprofloxacin, ofloxacin and norfloxacin activities were evaluated by agar dilution using Mueller-Hinton agar accor ding to NCCLS recommendations. Of the 162 isolates, 16 (9.8%) were intermed iate and 146 (90.1%) resistant to ciprofloxacin. 95 of the 162 strains (58. 6%) were susceptible, 27 (16.7%) intermediately susceptible, and 40 strains (24.7%) were resistant to clinafloxacin. The percentage susceptible to cli nafloxacin was 65.6% for E. coli, 75% for K. pneumoniae, 71.4% for P. mirab ilis, 28.6% for S. marcescens, 75% for E. cloacae, 33.3% for P. aeruginosa, 90.5% for S. aureus and 40% for Enterococcus spp. Clinafloxacin was active against 58.6% of the ciprofloxacin-resistant clinical isolates tested. It was particularly active against S. aureus strains resistant to both ciprofl oxacin and methicillin. (C) 1999 Elsevier Science B.V. and International So ciety of Chemotherapy. All rights reserved.