Clinical implications of varying degrees of vancomycin susceptibility in methicillin-resistant Staphylococcus aureus bacteremia

Emerg Infect Dis. 2003 Jun;9(6):657-64. doi: 10.3201/eid0906.030001.

Abstract

We conducted a retrospective study of the clinical aspects of bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) with heterogeneously reduced susceptibility to vancomycin. Bloodstream MRSA isolates were screened for reduced susceptibility by using brain-heart infusion agar, including 4 mg/L vancomycin with and without 4% NaCl. Patients whose isolates exhibited growth (case-patients) were compared with those whose isolates did not (controls) for demographics, coexisting chronic conditions, hospital events, antibiotic exposures, and outcomes. Sixty-one (41%) of 149 isolates exhibited growth. Subclones from 46 (75%) of these had a higher MIC of vancomycin than did their parent isolates. No isolates met criteria for vancomycin heteroresistance. No differences in potential predictors or in outcomes were found between case-patients and controls. These data show that patients with vancomycin-susceptible MRSA bacteremia have similar baseline clinical features and outcomes whether or not their bacterial isolates exhibit growth on screening media containing vancomycin.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacteremia / diagnosis
  • Bacteremia / drug therapy*
  • Cohort Studies
  • Electrophoresis, Gel, Pulsed-Field
  • Female
  • Hospitalization
  • Humans
  • Male
  • Methicillin Resistance
  • Microbial Sensitivity Tests
  • Retrospective Studies
  • Staphylococcal Infections / diagnosis
  • Staphylococcal Infections / drug therapy*
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / genetics
  • Staphylococcus aureus / isolation & purification
  • Staphylococcus aureus / pathogenicity
  • Vancomycin / administration & dosage
  • Vancomycin / pharmacology*
  • Vancomycin Resistance

Substances

  • Vancomycin