Key clinical point: Filamentous bacteriophage is prevalent in cystic fibrosis patients with Pseudomonas aeruginosa infections and likely contributes to clinical outcomes.

Major finding: The prevalence of filamentous bacteriophage was 36.2% in cystic fibrosis patients with P. aeruginosa infection and 27.6% in all cystic fibrosis patients.

Study details: A multicohort study that included a Danish longitudinal cohort of 34 patients and a prospective cross-sectional cohort of 76 patients at Stanford (Calif.) University, all with cystic fibrosis.

Disclosures: One author reported receiving grants from the Cystic Fibrosis Foundation, clinical trial support, and consulting fees from industry. Two other authors are inventors on a patent application that covers the development of a vaccine that targets filamentous bacteriophage. The others reported no conflicts of interest.