Vancomycin MIC in MSSA: A Virulence Marker?

Does reduced vancomycin susceptibility not only confer drug resistance but also reveal a virulence phenotype?

Vancomycin has been the cornerstone of empiric antistaphylococcal therapy since prevalence of methicillin-resistant Staphylococcus aureus (MRSA) surpassed methicillin-susceptible S. aureus (MSSA) in soft tissue and other invasive infections. MRSA prevalence has declined since its peak 10 years ago, but not sufficiently to reestablish empiric beta-lactam therapy. Increasing vancomycin minimal inhibitory concentrations (MICs) within the susceptible range have been associated with worse outcomes, not only for MRSA-infected vancomycin recipients but also in several studies of MSSA-infected beta-lactam recipients, raising concern that reduced vancomycin susceptibility confers not only drug resistance but also a marker of a virulence phenotype.

Th…

Reviewing Author

George Sakoulas, MD

Disclosures

Consultant/Advisory BoardParatek Pharmaceuticals; Nestle Corp.; AbbVie; Shionogi

Speaker’s BureauAllergan/AbbVie; Paratek Pharmaceuticals; Nestle Corp.

RoyaltiesUpToDate

Editorial BoardsAntimicrobial Agents and Chemotherapy; Open Forum Infectious Diseases