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Efficacy of ofloxacin in experimental Staphylococcus aureus endocarditis
G W Kaatz1, S M Seo, S L Barriere
1Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan.
Abstract:
The efficacy of ofloxacin was compared with that of vancomycin in the therapy of experimental Staphylococcus aureus endocarditis. Rabbits infected with either a methicillin-susceptible (MSSA-1199) or a methicillin-resistant (MRSA-494) test strain were treated with ofloxacin (20 mg/kg of body weight every 8 h) or vancomycin (17.5 mg/kg of body weight every 6 h) for 4 days. The antimicrobial agents were found to be equally effective in clearing bacteremia and in reducing bacterial counts in vegetations and in renal and splenic tissue of animals infected with either test strain. The drugs were of equal efficacy in curing MRSA-494 endocarditis. No resistance to ofloxacin emerged in either test strain during therapy. We conclude that in this model ofloxacin is as efficacious as vancomycin and that, unlike for other fluoroquinolones we have evaluated, resistance to the drug does not develop during therapy of this serious S. aureus infection.
Insights
Ofloxacin demonstrated equal efficacy to vancomycin in treating experimental Staphylococcus aureus endocarditis in rabbits. Importantly, no ofloxacin resistance developed during this study, offering a promising alternative treatment.
Area of Science:
- Infectious Diseases
- Pharmacology
- Microbiology
Background:
- Staphylococcus aureus endocarditis is a severe infection often requiring potent antimicrobial therapy.
- Vancomycin is a standard treatment, but concerns exist regarding emerging resistance.
- Fluoroquinolones are broad-spectrum antibiotics with varying efficacy and resistance profiles.
Purpose of the Study:
- To compare the efficacy of ofloxacin with vancomycin in treating experimental Staphylococcus aureus endocarditis.
- To evaluate the development of antibiotic resistance during therapy.
- To assess the effectiveness against both methicillin-susceptible and methicillin-resistant strains.
Main Methods:
- Experimental endocarditis was induced in rabbits using methicillin-susceptible (MSSA-1199) and methicillin-resistant (MRSA-494) Staphylococcus aureus strains.
- Animals were treated with either ofloxacin or vancomycin for 4 days.
- Efficacy was assessed by monitoring bacteremia, bacterial counts in vegetations, and tissue samples, and by evaluating resistance development.
Main Results:
- Ofloxacin and vancomycin showed comparable efficacy in clearing bacteremia and reducing bacterial loads in infected tissues.
- Both drugs were equally effective in curing MRSA-494 endocarditis.
- No ofloxacin resistance emerged in either MSSA or MRSA strains during the treatment period.
Conclusions:
- Ofloxacin is as efficacious as vancomycin in this rabbit model of Staphylococcus aureus endocarditis.
- Unlike other fluoroquinolones, ofloxacin did not induce resistance during therapy for this serious infection.
- Ofloxacin presents a potentially valuable therapeutic option for Staphylococcus aureus endocarditis, especially considering the lack of resistance development.