Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Commensal-colonization-factor-producing Bacteroidetes protect against Klebsiella pneumoniae colonization and infection in the gut via IL-36 signalling and macrophages, and these commensals can limit transmission between hosts, whereas Proteobacteria are important for colonization resistance in the upper airway.