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Published on: May 8, 2013

Development of reduced vancomycin susceptibility in methicillin-susceptible Staphylococcus aureus

Satish K Pillai1, Christine Wennersten, Lata Venkataraman

  • 1Division of Infectious Diseases, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, Massachusetts 02215, USA. spillai@bidmc.harvard.edu

Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America
|September 23, 2009
PubMed
Abstract

Insights

Reduced vancomycin susceptibility can emerge in methicillin-susceptible Staphylococcus aureus (MSSA). This evolution may lead to decreased susceptibility to other antibiotics, impacting treatment options.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Antibiotic Resistance

Background:

  • Reduced vancomycin susceptibility in Staphylococcus aureus is typically associated with methicillin-resistant strains (MRSA).
  • This study investigates the emergence of reduced vancomycin susceptibility in methicillin-susceptible S. aureus (MSSA) clinical isolates.
  • An isogenic series of MSSA isolates was used to compare resistance evolution with that in MRSA.

Purpose of the Study:

  • To determine if the evolution of reduced vancomycin susceptibility in MSSA mirrors that observed in MRSA.
  • To investigate the impact of developing vancomycin intermediate susceptibility on other antibiotic susceptibilities and bacterial characteristics in MSSA.

Main Methods:

  • Analysis of vancomycin population profiles.
  • Measurement of chemical autolysis.
  • Determination of minimum inhibitory concentrations (MICs) for vancomycin, oxacillin, and daptomycin.
  • Assessment of bactericidal activities of vancomycin, oxacillin, and daptomycin.

Main Results:

  • Progressive vancomycin resistance correlated with increased daptomycin nonsusceptibility.
  • The vancomycin-intermediate MSSA isolate exhibited reduced chemical autolysis compared to the susceptible progenitor.
  • Bactericidal activity of vancomycin, oxacillin, and daptomycin was diminished in the vancomycin-intermediate MSSA isolate.

Conclusions:

  • Reduced vancomycin susceptibility can develop in S. aureus regardless of methicillin susceptibility.
  • The emergence of vancomycin intermediate susceptibility in MSSA can lead to cross-tolerance to other anti-staphylococcal antibiotics.
  • Clinicians must be aware of vancomycin resistance development in MSSA and its implications for patient treatment.

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