title: Vancomycin minimum inhibitory concentrations and lethality in Staphylococcus aureus bacteremia.
abstract: BACKGROUND
  After the dissemination of penicillin and oxacillin resistance in Staphylococcus aureus, vancomycin-intermediate and vancomycin resistant isolates have been reported. Even between isolates with minimum inhibitory concentrations (MICs) within the susceptible range, some authors have demonstrated that higher MICs correlate with higher lethality.
  
  
  METHODS
  To test this hypothesis in our setting, we compared vancomycin MICs evaluated by two methods and clinical outcomes in hospitalized patients with S. aureus bacteremia.
  
  
  RESULTS
  We compared lethality in patients infected with isolates that had MICs under or over 2 mg/L. Among patients infected with isolates that had microdilution MICs <2 mg/L, the lethality was 25%; among patients infected with strains that had microdilution MICs ≥2 mg/L, 33% died. Among patients infected with isolates that had Etest MICs <2 mg/L, 23% died; in comparison, patients infected with strains that had Etest MICs ≥2 mg/L had a lethality of 44%.
  
  
  CONCLUSIONS
  Our results showed a slight tendency of higher lethality when higher MICs were present. However, this difference did not reach statistical significance, possibly due to the relatively small number of patients included in the study. Future prospective studies are needed to further evaluate this correlation and to help clinicians guide antimicrobial therapy.
authors.affiliation: Division of Microbiology, Department of Pathology, Santa Casa School of Medicine, São Paulo, Brazil.
authors.forename: Felipe
authors.initials: F
authors.lastname: Sulla
authors.affiliation: Division of Microbiology, Department of Pathology, Santa Casa School of Medicine, São Paulo, Brazil.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Bussius
authors.affiliation: Division of Microbiology, Department of Pathology, Santa Casa School of Medicine, São Paulo, Brazil.
authors.forename: Felipe
authors.initials: F
authors.lastname: Acquesta
authors.affiliation: PhD, Division of Microbiology, Department of Pathology, Santa Casa School of Medicine, São Paulo, Brazil.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Navarini
authors.affiliation: Division of Microbiology, Department of Pathology, Santa Casa School of Medicine, São Paulo, Brazil.
authors.forename: Suzethe M
authors.initials: SM
authors.lastname: Sasagawa
authors.affiliation: MD, PhD, Division of Microbiology, Department of Pathology, Santa Casa School of Medicine, São Paulo, Brazil, Division of Infectious Diseases, Department of Pediatrics, Santa Casa School of Medicine, São Paulo, Brazil.
authors.forename: Marcelo J
authors.initials: MJ
authors.lastname: Mimica
keywords: S. aureus; susceptibility; vancomycin