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Coagulase-negative staphylococcal bloodstream infections: does vancomycin remain appropriate empiric therapy?
J Infect. 2015 Feb 25;
Authors: Valencia-Rey P, Weinberg J, Miller NS, Barlam T
Abstract
OBJECTIVES: It is unknown if vancomycin minimal inhibitory concentrations (MICs) have increased in coagulase-negative staphylococci (CoNS) or whether vancomycin remains appropriate empiric therapy.
METHODS: We performed a retrospective study at a single tertiary care center over 8 years. Adult inpatients with ≥2 positive blood cultures for CoNS within a 48-hour period were eligible. Susceptibilities were performed by automated broth based-microdilution. Changes in antimicrobial susceptibility were analyzed using logistic regression. The clinical characteristics and outcomes of patients with bloodstream infections (BSI) were compared by MIC.
RESULTS: Of 308 episodes of possible CoNS bacteremia, the vancomycin MIC was ≤1μg/mL in 80 (26%) isolates, 2μg/mL in 223 (72.4%) isolates and 4μg/mL in 5 (1.6%) isolates. No isolates were resistant. We observed an 11-fold increased chance of having an isolate with a vancomycin MIC ≤1μg/mL in 2009-2011 compared with 2004-2008 (OR 10.8, 95%CI 6.0-19.5, p<0.05). In 152 patients with BSI, the median days of bacteremia, hospital mortality and readmissions at 30 days were similar in BSI caused by isolates with high vancomycin MICs (2-4μg/mL) and low vancomycin MICs (≤1μg/mL).
CONCLUSIONS: We conclude vancomycin is still appropriate empiric therapy for CoNS BSIs. CoNS vancomycin MICs decreased over the study period despite widespread use of vancomycin.
PMID: 25725152 [PubMed - as supplied by publisher]