Successful Use of Ceftolozane-Tazobactam to Treat a Pulmonary Exacerbation of Cystic Fibrosis Caused by Multidrug-Resistant Pseudomonas aeruginosa.

Ceftolozane-tazobactam, a novel β-lactam/β-lactamase inhibitor, was recently approved for the treatment of complicated urinary tract and intraabdominal infections, as monotherapy and in combination with metronidazole, respectively. Ceftolozane-tazobactam exhibits a wide spectrum of activity against both gram-positive bacteria, gram-negative bacteria including multidrug-resistant (MDR) Pseudomonas aeruginosa, and some anaerobic bacteria. Although not currently approved for any pulmonary indication, studies have demonstrated excellent distribution to epithelial lining fluid, indicating that it may be an alternative agent to use in the treatment of respiratory tract infections caused by MDRP. aeruginosa. Unfortunately, data are lacking regarding the use of ceftolozane-tazobactam in the treatment of respiratory tract infections including patients with cystic fibrosis (CF). We describe the first case report, to our knowledge, of a 25-year-old white man successfully treated with ceftolozane-tazobactam for a pulmonary exacerbation of his CF caused by MDRP. aeruginosa. He was admitted for his fourth hospitalization in 7 months for a pulmonary exacerbation of his CF. After blood and sputum were cultured, prednisone, cefepime, inhaled tobramycin, and intravenous ciprofloxacin were started. On day 4, after no signs of clinical improvement, respiratory cultures revealed nonmucoid MDRP. aeruginosa, susceptible only to colistin. β-Lactam therapy was subsequently changed to ceftolozane-tazobactam 3 g intravenously every 8 hours while continuing ciprofloxacin and inhaled tobramycin. Ceftolozane-tazobactam susceptibility was determined by the Etest method (minimum inhibitory concentration 1.5 μg/ml). By day 3 of therapy, the patient showed signs of clinical improvement and was discharged after completion of a 12-day course of antibiotics. Until additional research is available, we hope this evidence will provide consideration of ceftolozane-tazobactam for this novel off-label indication.