Use of continuous infusion ceftolozane–tazobactam with therapeutic drug monitoring in a patient with cystic fibrosis

Purpose The safe and effective use of ceftolozane–tazobactam delivered via continuous infusion in a cystic fibrosis (CF) patient with reduced body weight and presumed augmented renal clearance is reported. Summary A 30-year-old woman with CF was admitted for acute pulmonary exacerbations with positive respiratory cultures for Pseudomonas aeruginosa and extended-spectrum β-lactamase-producing Escherichia coli. Susceptibility testing confirmed multidrug resistance, and the patient was transitioned to ceftolozane–tazobactam for definitive therapy. A novel strategy of administering ceftolozane–tazobactam 6 g by continuous i.v. infusion over 24 hours was initiated during hospitalization and continued at discharge for a total of 10 days. Therapeutic drug monitoring over the first 36 hours of the continuous infusion confirmed adequate exposure. The patient had clinical resolution with return to baseline of pulmonary function tests and no noted adverse drug events. Conclusion A continuous infusion regimen of ceftolozane–tazobactam was successfully used in a CF patient with augmented renal clearance.