Vancomycin Minimum Inhibitory Concentration as a Predictor of Mortality in Methicillin‐ResistantStaphylococcus aureusBacteremia: A Second Look

Abstract

To the Editor—We read with interest the article by Soriano et al. [1] that described vancomycin MIC as a predictor of mortality in patients with methicillin-resistant Staphylococcus aureus bacteremia. The issue of MIC “creep” was documented elsewhere [2], and the conclusion that a higher MIC is associated with an increased risk of mortality is not surprising. In addition, the presence of shock associated with methicillin-resistant Staphylococcus aureus bacteremia was documented elsewhere as a risk factor for mortality [3]. However, the negative association between the development of shock and vancomycin MIC is extremely intriguing. Soriano et al. [1] hypothesize that this relationship could be attributed to a decrease in pathogenicity as resistance increases through a variety of mechanisms. We offer an alternative explanation of the data and address some concerns with the study by Soriano et al. [1].