Comparative efficacy of gemifloxacin in experimental models of pyelonephritis and wound infection

Gemifloxacin (SB-265805) is a potent, novel fluoroquinolone with broad-spectrum antimicrobial activity. In this study, the efficacy of gemifloxacin was studied in experimental models of Gram-negative pyelonephritis (caused by Escherichia coli or Proteus mirabilis) and Gram-positive wound infection resulting from Streptococcus pyogenes, Staphylococcus epidermidis or Staphylococcus aureus. Gemifloxacin activity against these pathogens was compared with those of amoxycillin-clavulanate, ciprofloxacin, cefuroxime, azithromycin, trovafloxacin, grepafloxacin, levofloxacin and tosufloxacin. Oral treatment was initiated 1 h after infection and continued once or twice daily for 3 days. Around 17 h after the end of treatment, animals were killed and the infected kidneys or the skin around the wound site were excised for the enumeration of viable bacteria. In the pyelonephritis model (either microorganism), gemifloxacin reduced bacterial numbers significantly (P < 0.01) compared with no treatment. No comparator agent had a greater effect than gemifloxacin. Notably, grepafloxacin and azithromycin were significantly less effective (P < 0.01) than gemifloxacin against E. coli pyelonephritis, and amoxycillin-clavulanate, azithromycin and trovafloxacin were inferior (P < 0.01) against P. mirabilis infection. In the S. pyogenes wound infection model, gemifloxacin, amoxycillin-clavulanate, cefuroxime and azithromycin reduced bacterial numbers significantly compared with controls (P < 0.01). Results for the comparator quinolones were not significantly different from untreated controls (P > 0.05). Gemifloxacin was also effective against staphylococcal infection, as were grepafloxacin and levofloxacin, while ciprofloxacin, trovafloxacin and tosufloxacin were significantly less effective against these pathogens than gemifloxacin (P < 0.01). No comparator agent had greater activity than gemifloxacin against S. pyogenes or S. aureus infections. These data demonstrate the potential benefit of gemifloxacin in the treatment of Gram-negative urinary tract infection and Gram-positive skin and soft tissue infection.