The Study
Colibactin genes are highly prevalent in the developing infant gut microbiome
This study found that lots of babies have certain bacteria in their poop that can make a chemical linked to cancer in adults. But it didn’t prove that these bacteria cause cancer — it just noticed they’re common when babies get antibiotics or stay in the NICU.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Some babies have gut bacteria that make a chemical that can damage DNA — the same chemical linked to colon cancer in adults.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though these bacteria are common in babies, most kids don’t get colon cancer — so something else (like genetics or later exposures) must decide if the damage leads to cancer.
- 2More than half of all babies (56–66%) had these bacteria in their poop before age 2.
- 3The most common bacteria were E.
- 4coli, but in sick preterm babies on antibiotics, Klebsiella was more likely to carry them.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Gut Microbes
Year
2025
Authors
S. Levy, K. McCauley, R. Strength, E. S. Robbins, Qing Chen, S. Namasivyam, G. Maxwell, S. K. Hourigan
Related Content
Claims (3)
Scientists do not yet know where infants get colibactin-producing bacteria, because these bacteria are rarely found in parents or in hospital environments, which suggests they may not be passed from mother to baby during birth as previously thought.
More than half of all infants carry bacteria that produce colibactin and have the pks gene cluster during their first two years of life. These bacteria are most commonly found between 6 and 12 months in healthy full-term babies, and between 12 and 24 months in babies cared for in neonatal intensive care units. This pattern suggests that such bacterial carriage is a typical part of early gut microbiome development.
DNA damage from certain bacteria in early childhood may lead to colorectal cancer that appears later in adulthood.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.