Prophylactic Post-lung Transplant Bacteriophage Therapy Against XDR Pseudomonas aeruginosa in Cystic Fibrosis: A Case Report

Lung transplant recipients (LTRs) with cystic fibrosis (CF) are frequently colonized with multidrug-resistant pathogens, including extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA), which increase peri-transplant morbidity. Bacteriophage therapy (BT) has shown efficacy against MDR bacteria, but its prophylactic use post-transplant has rarely been reported. A 46-year-old woman with CF and chronic lung allograft dysfunction (bronchiolitis obliterans syndrome III) after bilateral transplantation in 2005 underwent retransplantation in 2024. She was colonized with XDR PA and Aspergillus spp. Peri-transplant prophylaxis included ceftolozane/tazobactam, intravenous and inhaled colistin, amoxicillin/clavulanic acid, and intravenous liposomal amphotericin B. BT was personalized based on phage susceptibility testing (PST) and initiated immediately post-transplant via combined intravenous and endobronchial administration for three weeks. Pulmonary cultures remained negative for XDR PA during this period. The patient ultimately developed multiorgan failure unrelated to XDR PA and died 88 days post-transplant. This is one of the first reported case of prophylactic BT in lung transplantation, achieving pulmonary microbiologic suppression of XDR PA. While the patient’s outcome was determined by other complications. Prospective studies are needed to define its efficacy, safety, and optimal administration.