Vancomycin Dosing for Pneumonia in Critically Ill Trauma Patients

Background: Vancomycin has been recommended as the treatment of choice for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia with a desired trough concentration of 15 to 20 mg/L. The purpose of this study was to evaluate the initial dosing of vancomycin for MRSA pneumonia in critically ill adult trauma patients. Methods: Critically ill adult trauma patients were retrospectively identified for inclusion into the study. Patients initiated at a dose of 1 g intravenously (i.v.) every 8 hours were compared with patients initiated at a dose of 1 g i.v. every 12 hours. Baseline continuous demographic variables and steady-state vancomycin trough concentrations were compared between the two groups using a Student's t test (alpha = 0.05). Results: There were 36 patients who satisfied criteria for inclusion 17 patients in the 1 g every 8 hour group and 19 patients in the 1 g every 12 hour group. The mean steady-state trough concentration was higher in the 1 g every 8 hour group versus the 1 g every 12 hour group (11.1 vs. 6.8 mg/L, p = 0.014). A steady-state trough concentration greater than 15 mg/L was achieved in 23.5% of the patients in the 1 g every 8 hour group and none of the patients in the 1 g every 12 hour group. Conclusion: A vancomycin regimen of 1 g i.v. every 12 hours in critically ill trauma patients with MRSA pneumonia and normal renal function is unlikely to achieve trough concentrations of 15 to 20 mg/L. Doses of at least 1 g i.v. every 8 hours are needed.