This is a Phase 1, open-label, multi-center pilot study evaluating the safety and microbiological activity of intravenous (IV) bacteriophage therapy in combination with standard IV antibiotics in adults with cystic fibrosis (CF) experiencing pulmonary exacerbations due to antibiotic-resistant bacterial infections. Eligible participants will receive a 7-day course of IV antibiotics, selected by their treating clinician, along with a phage cocktail specifically formulated to target their identified bacterial pathogen (Pseudomonas aeruginosa, Klebsiella spp., Stenotrophomonas maltophilia, Escherichia coli, Staphylococcus aureus, or Achromobacter xylosoxidans). The primary objective is to assess the safety and tolerability of this combined treatment approach. Secondary and exploratory outcomes include assessment of changes in sputum bacterial burden, lung function (spirometry and oscillometry), quality of life, and bacteriophage pharmacokinetics. Results from this study will inform the feasibility and design of future clinical trials using phage therapy in the CF population.
Age ≥ 18 years.
Confirmed diagnosis of cystic fibrosis.
Sputum culture within 24 months and at screening showing at least one of the following: Pseudomonas aeruginosa, Klebsiella spp., Stenotrophomonas maltophilia, Escherichia coli, Staphylococcus aureus, or Achromobacter xylosoxidans.
Percent predicted FEV₁ ≥ 40% (GLI).
Untreated or uncontrolled mycobacterial or fungal airway infection.
History of Clostridioides difficile without a negative test within 3 months. Concerning exotoxin, virulence, or resistance genes in the bacterial isolate (per investigator).
Mixed-species bacterial infection at screening.
Participation in another interventional trial within 30 days.