Association of Vancomycin AUC/MIC and Trough Concentration With Early Clinical Response in Enterococcus or Coagulase‐Negative Staphylococcus Infection: A Prospective Study

This study was condcuted to examine the association of area under the curve (AUC)/minimum inhibitory concentration (MIC) and trough concentration (C trough ) of vancomycin with treatment outcome and nephrotoxicity in infections caused by Enterococcus spp. and coagulase‐negative Staphylococci (CoNS). Peak and trough concentrations were used to calculate AUC in 89 patients receiving vancomycin for infections with Enterococcus spp. (n = 65) or CoNS (n = 24). Correlations between C trough , AUC/MIC, early clinical response (ECR), and nephrotoxicity were assessed and cutoff values were determined. Sixty‐three (70.8%) patients showed improvement in ECR and 10 (11.2%) experienced nephrotoxicity. Enterococcus spp. infections displayed correlations between AUC/MIC and ECR for AUC 0‐24 h /MIC (r 2 = 0.27, P ≤ .05) and AUC 24‐48 h /MIC (r 2 = 0.28, P ≤ .05), but not for C trough (r 2 = 0.21, P > .05). There were no correlations between C trough (r 2 = 0.26, P > .05), AUC 0‐24 h /MIC (r 2 = −0.12, P > .05), AUC 24‐48 h /MIC (r 2 = 0.01, P > .05) and ECR for CoNS. In the CoNS group, a moderate correlation was found between ECR and C trough at a cutoff value of 6.9 μg/mL. In addition, nephrotoxicity is also moderately associated with AUC 0‐24 h and AUC 24‐48 h at 505.7 and 667.1 μg•h/mL, respectively. A strong correlation between nephrotoxicity and C trough was observed when the cutoff value was 18.9 μg/mL. AUC/MIC during the first 48 h was a determinant of vancomycin efficacy in Enterococcus infections but not for CoNS. C trough was not correlated with clinical outcome. Nephrotoxicity could be predicted using C trough and AUC for infections with both pathogens.