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Ciprofloxacin versus vancomycin in the therapy of experimental methicillin-resistant Staphylococcus aureus
Abstract:
We compared the efficacy of ciprofloxacin with that of vancomycin by using the rabbit model of methicillin-resistant Staphylococcus aureus endocarditis. Endocarditis was treated with ciprofloxacin (25 mg/kg [body weight] intravenously every 8 h) or vancomycin (17.5 mg/kg intravenously every 6 h) for 3 days. Vancomycin and ciprofloxacin were equally efficacious in clearing bacteremia. Both reduced vegetation bacterial counts by 5 log10 CFU/g and renal and splenic bacterial counts by more than 3 log10 CFU/g as compared with untreated control rabbits after 26 h of infection (P less than 0.001). Both antimicrobial agents were able to eradicate the infectious process in an equivalent proportion of animals. No methicillin-resistant S. aureus that was recovered from ciprofloxacin-treated rabbits developed resistance to ciprofloxacin during therapy. Peak concentrations of ciprofloxacin in the sera of rabbits with endocarditis were significantly higher than those predicted by single-dose studies in uninfected rabbits. This finding was likely due to changes in the pharmacokinetics of the drug with multiple dosing and in infected versus uninfected rabbits. This study demonstrated that intravenously administered ciprofloxacin is as efficacious as vancomycin is in an in vivo model of a serious systemic methicillin-resistant S. aureus infection.
Insights
Ciprofloxacin and vancomycin show equal efficacy in treating methicillin-resistant Staphylococcus aureus endocarditis in rabbits. Both antibiotics effectively cleared bacteremia and reduced bacterial counts, demonstrating comparable effectiveness in this infection model.
Area of Science:
- Infectious Diseases
- Pharmacology
- Microbiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) causes severe systemic infections like endocarditis.
- Vancomycin is a standard treatment, but concerns about resistance and efficacy exist.
- Novel treatment strategies for MRSA infections are crucial.
Purpose of the Study:
- To compare the in vivo efficacy of ciprofloxacin and vancomycin for treating MRSA endocarditis.
- To evaluate bacteremia clearance, bacterial load reduction, and eradication rates.
- To assess the development of antimicrobial resistance during treatment.
Main Methods:
- A rabbit model of experimental endocarditis caused by MRSA was utilized.
- Animals were treated with intravenous ciprofloxacin or vancomycin for 3 days.
- Efficacy was assessed by measuring bacteremia, vegetation bacterial counts, and organ bacterial loads.
Main Results:
- Both ciprofloxacin and vancomycin demonstrated equal efficacy in clearing bacteremia.
- Both agents significantly reduced vegetation and organ bacterial counts compared to controls.
- No development of ciprofloxacin resistance was observed in recovered MRSA strains.
- Achieved peak serum concentrations of ciprofloxacin were higher than predicted, suggesting altered pharmacokinetics.
Conclusions:
- Intravenously administered ciprofloxacin is as efficacious as vancomycin in a rabbit model of MRSA endocarditis.
- Ciprofloxacin represents a viable alternative treatment option for serious systemic MRSA infections.
- Further pharmacokinetic studies are warranted to understand dosing adjustments in infected states.