Clinical meaning
Vancomycin's bactericidal activity against gram-positive organisms is concentration-independent and time-dependent, with efficacy best predicted by the AUC/MIC ratio. The 2020 ASHP/IDSA/SIDP guidelines recommend AUC-guided dosing targeting AUC/MIC 400-600 mg·h/L (assuming MIC ≤1 mcg/mL) rather than trough-only monitoring to optimize efficacy while reducing nephrotoxicity. Vancomycin distributes into most body tissues but CNS penetration is variable. Renal elimination accounts for 80-90% of clearance, necessitating dosage adjustment based on creatinine clearance or estimated GFR. The clinician must prescribe appropriate loading and maintenance doses, order therapeutic drug monitoring, interpret pharmacokinetic parameters, and manage complications including nephrotoxicity, ototoxicity, and infusion reactions.
Diagnosis & workup
Diagnostics & workup: - Order AUC-guided monitoring using Bayesian software or two-level sampling (peak and trough) - Target AUC/MIC 400-600 mg·h/L for serious MRSA infections - Order baseline and serial serum creatinine, BUN, and eGFR - Order vancomycin MIC from culture susceptibility to guide therapy selection - If MIC >1: consider alternative agents (daptomycin, linezolid, ceftaroline) - Order baseline audiometry for anticipated therapy >14 days - Monitor CBC weekly for vancomycin-induced neutropenia