Antibiotic choice may not explain poorer outcomes in patients with Staphylococcus aureus bacteremia and high vancomycin minimum inhibitory concentrations

Natasha Holmes, John Turnidge, Wendy Munckhof, James Robinson, Tony Korman, Matthew O'Sullivan, Tara Anderson, Sally Roberts, Wei Gao, Keryn Christiansen, Geoffrey Coombs, Paul DR Johnson, Benjamin Howden

Research output: Contribution to journalArticleResearchpeer-review

202 Citations (Scopus)


There are concerns about reduced efficacy of vancomycin in patients with Staphylococcus aureus bacteremia (SAB), especially when the minimum inhibitory concentration (MIC) nears the upper limit of the susceptible range. METHODS: We examined the relationship between antibiotic treatment, 30-day mortality, and microbiologic parameters in a large Australasian cohort of patients with SAB. RESULTS: We assessed 532 patients with SAB from 8 hospitals. All patients with methicillin-resistant S. aureus (MRSA) bacteremia were treated with vancomycin, and patients with methicillin-susceptible S. aureus (MSSA) bacteremia received either flucloxacillin or vancomycin. Increasing vancomycin MIC was associated with increased mortality in vancomycin-treated patients. However, even in patients with MSSA bacteremia treated with flucloxacillin, mortality was also higher if the vancomycin Etest MIC of their isolate was >1.5 mug/mL, compared with those with lower MIC isolates (26.8 vs 12.2 ; P <.001). After adjustment in a multivariate model, age, hospital-onset SAB and vancomycin MIC were independently associated with mortality, but methicillin resistance and antibiotic choice were not. CONCLUSIONS: We have confirmed an association between higher vancomycin MIC and increased mortality in patients with SAB, but surprisingly this relationship was not related to the antibiotic treatment received, suggesting that the use of vancomycin per se is not responsible for the poorer outcome.
Original languageEnglish
Pages (from-to)340 - 347
Number of pages8
JournalThe Journal of Infectious Diseases
Issue number3
Publication statusPublished - 2011

Cite this