Influence of pharmacokinetic/pharmacodynamic ratio on vancomycin treatment response in pediatric patients with Staphylococcus aureus bacteremia.

BACKGROUND

Staphylococcus aureus is a frequent cause of hospital-acquired bacteremia in pediatric patients. Vancomycin is the drug of choice for the treatment of methicillin-resistant strains, although treatment failure is frequently observed. Area under the curve (AUC) of plasma concentrations over the minimum inhibitory concentration (MIC) has been proposed as the best index to predict treatment response, although information about its clinical impact on pediatric patients is scarce. The objective of this study is to determine if early recovery of an AUC/MIC>400 mg*h/L for vancomycin in pediatric patients with S. aureus bacteremia is associated with clinical and microbiological treatment response.

METHODS

Retrospective observational study. Pediatric patients younger than 3 years with vancomycin-treated S. aureus bacteremia were included. The pharmacokinetic parameters were calculated from the vancomycin value obtained in the first 72 hours of treatment, assuming a bicompartmental model. A multivariate analysis was performed to analyze factors associated with early clinical response, treatment failure, microbiological response and 30-day mortality.

RESULTS

Fifty-one patients with S. aureus bacteremia were included in the study. In 18 patients (35.3%), strains with a MIC higher than 1.0 mg/L were isolated, being in eight (15.7%) greater than 1.5 mg/L. 22 (43.1%) patients did not reach an estimated AUC/MIC>400 during the first 72 hours. A significant association was observed between attainment of an AUC/MIC>400 and early clinical response (OR:3.23 [95% CI: 1.07-12.03]). No significant association was found between an AUC/MIC>400 and microbiological response or mortality.

CONCLUSIONS

An AUC/MIC>400 is associated with early response to vancomycin in pediatric patients with S. aureus bacteremia.