Failure of ceftolozane‐tazobactam salvage therapy in complicated pneumonia with lung abscess

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.