Within-host genetic diversity of extended spectrum beta-lactamase (ESBL)-producing Enterobacterales

We aimed to study the long-term genetic diversity of colonizing and infecting ESBL-Escherichia coli and ESBL-Klebsiella pneumoniae species complex isolates collected from individual patients over time. We frequently observed isolates of the same strain recovered from different body sites associated with either colonization or infection. Antimicrobial resistance genes, plasmid replicons, and whole ESBL-plasmids were shared between isolates regardless of chromosomal relatedness. Ours study suggests that patients colonized with ESBL-producers may act as durable reservoirs for ongoing transmission of ESBLs, and they are at a prolonged risk of recurrent infection with colonizing strains.