Pf bacteriophages hinder sputum antibiotic diffusion via electrostatic binding

Abstract

AbstractDespite great progress in the field, chronicPseudomonas aeruginosa(Pa) infections remain a major cause of morbidity and mortality in patients with cystic fibrosis, necessitating treatment with inhaled antibiotics. Pf phage is a filamentous bacteriophage produced byPathat has been reported to act as a structural element inPabiofilms. Pf presence has been associated with resistance to antibiotics and poor outcomes in cystic fibrosis, though the underlying mechanisms are unclear. Here, we have investigated how Pf phages and sputum biopolymers impede antibiotic diffusion using human sputum samples and fluorescent recovery after photobleaching. We demonstrate that tobramycin interacts with Pf phages and sputum polymers through electrostatic interactions. We also developed a set of mathematical models to analyze the complex observations. Our analysis suggests that Pf phages in sputum reduce the diffusion of charged antibiotics due to a greater binding constant associated with organized liquid crystalline structures formed between Pf phages and sputum polymers. This study provides insights into antibiotic tolerance mechanisms in chronicPainfections and may offer potential strategies for novel therapeutic approaches.TeaserPf phages and sputum polymers reduce antibiotic diffusion via electrostatic interactions and liquid crystal formation.