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Antibiotic choice may not explain poorer outcomes in patients with Staphylococcus aureus bacteremia and high

Natasha E Holmes1, John D Turnidge, Wendy J Munckhof

  • 1Department of Infectious Diseases, Austin Health, Heidelberg, Australia. natasha.holmes@austin.org.au

The Journal of Infectious Diseases
|July 12, 2011
PubMed
Abstract

Insights

Higher vancomycin minimum inhibitory concentration (MIC) is linked to increased mortality in Staphylococcus aureus bacteremia (SAB). This association persists regardless of antibiotic choice, suggesting vancomycin itself isn

Area of Science:

  • Infectious Diseases
  • Clinical Microbiology
  • Pharmacology

Background:

  • Concerns exist regarding vancomycin's reduced efficacy in Staphylococcus aureus bacteremia (SAB), particularly with elevated minimum inhibitory concentrations (MICs).
  • Understanding factors influencing SAB outcomes is crucial for effective patient management.

Purpose of the Study:

  • To investigate the relationship between antibiotic treatment, vancomycin MIC, and 30-day mortality in a large cohort of patients with SAB.
  • To determine if vancomycin MIC or antibiotic choice is independently associated with mortality in SAB.

Main Methods:

  • Retrospective analysis of 532 patients with SAB across 8 Australasian hospitals.
  • Examination of treatment regimens (vancomycin or flucloxacillin) and vancomycin MIC values (Etest).
  • Multivariate regression analysis to identify independent predictors of 30-day mortality.

Main Results:

  • Increasing vancomycin MIC was associated with higher mortality in vancomycin-treated patients.
  • Mortality was also higher in flucloxacillin-treated patients with vancomycin Etest MIC >1.5 μg/mL compared to those with lower MICs (26.8% vs 12.2%).
  • Independent predictors of mortality included age, hospital-onset SAB, and vancomycin MIC; methicillin resistance and antibiotic choice were not significant.

Conclusions:

  • A higher vancomycin MIC is confirmed as a significant predictor of increased mortality in SAB.
  • The association between higher vancomycin MIC and mortality was independent of the specific antibiotic treatment received.
  • These findings suggest that the elevated vancomycin MIC, rather than vancomycin use itself, is linked to poorer outcomes in SAB.

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