Pharmacokinetics of continuous infusion ceftolozane/tazobactam in two patients with extensive total body surface area burns.

Introduction: Treatment of infections in patients with burn injuries is challenging due to altered antimicrobial pharmacokinetics. Continuous infusion β-lactam therapy may be a useful antimicrobial stewardship strategy to improve pharmacodynamic target attainment in this population.

Case summaries: This report highlights the use of continuous infusion ceftolozane/tazobactam (C/T) in two patients with extensive total body surface area (TBSA) burns, suspected augmented renal clearance (ARC), and bloodstream infections caused by Pseudomonas aeruginosa with difficult-to-treat resistance (DTR P. aeruginosa). Both patients received C/T 9 g/day via continuous infusion. Minimum inhibitory concentrations (MIC) of C/T were 8/4 and 4/4 μg/mL in Cases 1 and 2, respectively.

Discussion: Despite similar patient characteristics, average free plasma ceftolozane concentrations were 41.6 mg/L in Case 1 and 22.8 mg/L in Case 2. Measured free concentrations exceeded 4 times the MIC for 100% of each 24-h infusion (fT > 4xMIC), and bacteremia was successfully cleared in each case.

Conclusion: These cases highlight the variability of drug exposure in patients with extensive TBSA burn injuries and support continuous infusion β-lactam therapy as a proactive strategy to optimize pharmacodynamic target attainment when pharmacokinetics are unpredictable.