Colorectal cancer (CRC) is a significant burden on human health. A growing body of work has pointed to critical roles for microbes in the exacerbation of and protection from the development of CRC. Specific Escherichia coli strains can produce colibactin, a genotoxin that has been implicated in exacerbating CRC. In this study, we tested human microbiotas in a mouse model of CRC and isolated a colibactin-positive Escherichia coli strain that led to tumorigenesis, disseminated from the gut to the mouse kidneys, caused death, and worsened both colitis and sepsis in murine models. Identification of this strain enhances our collective knowledge and adds an important tool for future studies on the role of microbes and CRC tumorigenesis.

SRI Stories: Mentoring through Microbes October 15, 2025 Above: Alexis Rousek Alexis Rousek didn’t always know she would become a microbiologist — but the signs were there early. In middle school, she...