Endocarditis due to methicillin-resistant Staphylococcus aureus in rabbits: expression of resistance to beta-lactam antibiotics in vivo and in vitro.

Abstract

Whether a strain of methicillin-resistant Staphylococcus aureus susceptible to cephalothin by the disk-diffusion method was also susceptible to cephalothin in vivo was evaluated in the rabbit model of endocarditis. Rabbits with aortic-valve endocarditis due to methicillin-resistant S. aureus that were treated for four days with cephalothin had the same numbers of organisms in vegetations as did untreated rabbits. Treatment with cephalothin caused emergence of a highly resistant subpopulation in aortic-valve vegetations. Organisms highly resistant to cephalothin were also highly resistant to nafcillin. Thus broth-dilution and disk-diffusion tests may not predict therapeutic failure for cephalothin against strains of methicillin-resistant S. aureus. Because of cross-resistances among beta-lactam drugs, these strains should be considered uniformly resistant to this general class of antimicrobial agents, regardless of results from these tests.

• Authors: H F Chambers, C J Hackbarth, T A Drake, M G Rusnak, M A Sande
• Journal: The Journal of infectious diseases (J Infect Dis) Vol. 149 Issue 6 Pg. 894-903 (Jun 1984) ISSN: 0022-1899 [Print] United States
• PMID: 6564133 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Nafcillin
• Vancomycin
• Methicillin
• Cephalothin

Topics

• Animals
• Anti-Bacterial Agents (pharmacology, therapeutic use)
• Cephalothin (pharmacology, therapeutic use)
• Endocarditis, Bacterial (drug therapy, microbiology)
• Methicillin (pharmacology)
• Microbial Sensitivity Tests
• Nafcillin (pharmacology)
• Penicillin Resistance
• Rabbits
• Staphylococcal Infections (drug therapy, microbiology)
• Staphylococcus aureus (drug effects)
• Vancomycin (pharmacology, therapeutic use)