Comparison of Efficacies of Oral Levofloxacin and Oral Ciprofloxacin in a Rabbit Model of a Staphylococcal Abscess

Oral levofloxacin was compared to oral ciprofloxacin in a Staphylococcus aureus subcutaneous abscess model in rabbits. Rabbits were surgically prepared with subcutaneous wiffle balls (43 mm in diameter) and allowed to recover for 4 to 6 weeks. Rabbits were infected by direct injection into the capsule with S. aureus ATCC 29213 (5 × 105 CFU) and were allowed to remain infected for 8 days before the initiation of anti-infective treatment. Efficacy was determined by assessing the bacterial load within the capsule over a 10-day treatment period. In single-dose pharmacokinetic studies in infected rabbits, similar area under the concentration-time curve/MIC ratios were obtained in the plasma and abscess fluid for levofloxacin at 45 mg/kg of body weight and ciprofloxacin at 200 mg/kg of body weight. Similar efficacies were seen with levofloxacin at 45 mg/kg/day and ciprofloxacin 400 mg/kg/day by day 10. In this model, levofloxacin was significantly more efficacious than ciprofloxacin (P < 0.01).