Pseudomonas aeruginosa aggregation and Psl expression in sputum is associated with antibiotic eradication failure in children with cystic fibrosis

Antibiotic eradication therapy of early P. aeruginosa infection in children with cystic fibrosis (CF) is key in preventing the detrimental impact of chronic infection. We previously demonstrated in vitro that P. aeruginosa isolates that persisted despite inhaled tobramycin treatment had increased anti-Psl antibody binding compared to those successfully eradicated. We aimed to validate these findings by directly visualizing P. aeruginosa in CF sputum.This was a prospective observational study of children with CF followed at SickKids with new-onset P. aeruginosa infection who underwent inhaled tobramycin eradication treatment. Using MiPACT, P. aeruginosa was visualized in a sputum sample obtained before treatment and classified as persistent or eradicated based on treatment outcomes. Initial isolates were also grown as biofilms in vitro and visualized using confocal microscopy.