Researchers from Canada and the US report on findings from a phenotypic, genomic, and phylogenetic study of Burkholderia cenocepacia isolates collected over time in chronically infected individuals with cystic fibrosis. Using more than 200 sputum samples obtained over two years to two decades from 16 individuals with cystic fibrosis, the team did systematic phenotyping and genotyping — paired with genome sequencing and comparative genomics — to tease out B.