Activity of Bacteriophages in Removing Biofilms of Pseudomonas aeruginosa Isolates from Chronic Rhinosinusitis Patients

Abstract

<b>Introduction:</b><i>Pseudomonas aeruginosa</i> infections are prevalent amongst chronic rhinosinusitis (CRS) sufferers. Many <i>P. aeruginosa</i> strains form biofilms, leading to treatment failure. Lytic bacteriophages (phages) are viruses that infect, replicate within, and lyse bacteria, causing bacterial death. <b>Aim:</b> To assess the activity of a phage cocktail in eradicating biofilms of <i>ex vivo P</i>.aeruginosa isolates from CRS patients. <b>Methods</b>: <i>P</i>. <i>aeruginosa</i> isolates from CRS patients with and without cystic fibrosis (CF) across three continents were multi-locus sequence typed and tested for antibiotic resistance. Biofilms grown <i>in vitro</i> were treated with a cocktail of four phages (CT-PA). Biofilm biomass was measured after 24 and 48 h, using a crystal violet assay. Phage titrations were performed to confirm replication of the phages. A linear mixed effects model was applied to assess the effects of treatment, time, CF status, and multidrug resistance on the biomass of the biofilm. <b>Results:</b> The isolates included 44 strain types. CT-PA treatment significantly reduced biofilm biomass at both 24 and 48 h post-treatment (<i>p</i> < 0.0001), regardless of CF status or antibiotic resistance. Biomass was decreased by a median of 76% at 48 h. Decrease in biofilm was accompanied by a rise in phage titres for all except one strain. <b>Conclusion:</b> A single dose of phages is able to significantly reduce biofilms formed <i>in vitro</i> by a range of <i>P</i>.aeruginosa isolates from CRS patients. This represents an exciting potential and novel targeted treatment for <i>P. aeruginosa</i> biofilm infections and multidrug resistant bacteria.