Colibactin genes are highly prevalent in the developing infant gut microbiome.

Early-life exposure to colibactin-producing pks+ gut bacteria is hypothesized to imprint mutations on the colorectal epithelium, increasing the risk of colorectal cancer later in life. We demonstrate an extremely high prevalence of pks+  bacteria (>50% of infants) during the first 2 y of life, suggesting carriage is likely normal during early-life microbiome development. Further investigation is required to understand the circumstances in which carriage can lead to mutagenesis.