Certain strains of Escherichia coli that produce colibactin cause distinct double-strand breaks in the DNA of cells lining the colon, leading to characteristic mutation patterns known as SBS88 and ID18.

Certain strains of E. coli that produce colibactin are linked to distinct patterns of DNA damage found in colorectal tumors, particularly in younger patients, and these damage patterns are found in a portion of the mutations that drive tumor development.

DNA damage caused by the bacterial toxin colibactin is found in the earliest genetic changes in colorectal cancer, suggesting that exposure to this toxin happens early in life and helps create the initial mutations that lead to cancer.

Colorectal cancers diagnosed before age 40 are more likely to show specific DNA damage patterns linked to colibactin-producing bacteria than cancers diagnosed after age 70, suggesting that exposure to these bacteria earlier in life may be associated with faster development of tumors in the lower colon and rectum.

When human colon tissue grown in the lab is exposed to a specific type of E. coli that produces colibactin for three months, it develops a unique pattern of DNA damage that matches the pattern seen in human colorectal cancers.

Colorectal tumors with specific DNA damage patterns caused by colibactin often do not contain the bacteria that produce it at the time of diagnosis, suggesting the bacteria were present earlier and have since been cleared.