Pf bacteriophage hinder sputum antibiotic diffusion via electrostatic binding
Qingquan Chen 1, Pam Cai 2, Tony Hong Wei Chang 1, Elizabeth Burgener 4, Michael J. Kratochvil 1,2, Aditi Gupta 3, Aviv Hargill 1, Carlos Milla 4, Sarah C. Heilshorn 3, Andy Spakowitz 2,3*, Paul L. Bollyky 1*
- Division of Infectious Diseases and Geographic Medicine, Dept. of Medicine, Stanford University School of Medicine, Beckman Center, 279 Campus Drive, Stanford, CA 94305
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305
- Department of Materials Science and Engineering, Stanford University, 476 Lomita Mall, Stanford, CA 94305
- Center for Excellence in Pulmonary Biology, Department of Pediatrics, Stanford University, Stanford, CA 94305
* Co-senior authors. Correspondence to: Paul Bollyky, MD, PhD: Department of Medicine, Division of Infectious Diseases, Stanford University, 279 Campus Drive, Beckman Center, Stanford CA 94305, USA. pbollyky@stanford.edu
Chronic Pseudomonas aeruginosa (Pa) infections remain a leading cause of morbidity and mortality in patients with cystic fibrosis (CF). Pa is problematic partly due to its production of robust biofilms, slimy communities of bacteria, and polymers that prevent the diffusion of antibiotics.
We have identified novel roles for filamentous bacteriophages, viruses produced by bacteria, in Pa biofilms. We reported that Pf acts as a structural element in P aeruginosa biofilms and enhances biofilm function by reducing the antimicrobial effects of tobramycin, thereby contributing to antibiotic tolerance. However, the mechanism of how Pf phages promote antimicrobial tolerance and how this interaction can be targeted for therapeutic purposes is unclear.
Here, by using fluorescent recovery after photobleaching (FRAP), we demonstrate that Pf4 interacts with anti-Pseudomonal antibiotics via charge-based electrostatic interactions. This interactive behavior is enhanced when Pf phages form highly organized structures with CF sputum polymers.
Finally, to target the interaction between Pf and antibiotics, we identified a commonly found antimicrobial peptide in the human airway that can enhance antibiotics penetration through Pf-positive biofilms and increase the bacterial killing efficacy of tobramycin treatment.