The study objective was to determine whether whole-genome sequencing can be used to determine the source of Pseudomonas aeruginosa infections in a cohort of high-risk burns patients.

All patients were screened on admission for P. aeruginosa and samples taken from their immediate environment and water. Patients with P. aeruginosa in their wounds, sputum, urine or stool were selected for enhanced environmental surveillance. All isolates of P. aeruginosa were whole-genome sequenced. Bioinformatics analysis placed isolates into a phylogenetic context to assess similarity and relatedness between isolates. 30 patients were screened for P. aeruginosa of which 5 patients were infected. Phylogenetic analysis revealed isolates were distributed across 8 distinct clades. A single clade dominated water and environmental samples in the burns unit. Analysis of microevolutionary changes revealed that genotypes collected in the water and environment of specific rooms were identical to those in two patient’s wounds. Distinct genotypes were found between different outlets within the same ward. In two patients, there was no clear link between the hospital environment and P. aeruginosa infection. Antibiotic therapy resulted in development of antibiotic resistance with associated genetic changes.