Treatment of Pseudomonas aeruginosa remains challenging, despite the availability ceftolozane-tazobactam. We report a treatment failure with ceftolozane-tazobactam salvage therapy for pneumonia complicated by lung abscess. Drug resistance, dose selection, and source control are possible contributing factors. Ceftolozane-tazobactam susceptibility testing should precede therapy and consideration should be given to dosing selection.
Keywords: Pseudomonas aeruginosa; ceftolozane‐tazobactam; pneumonia; resistance; treatment failure.