# In mouse and in vitro models, bowel preparation promotes pathogen colonization, translocation, and exacerbation of inflammation

## TL;DR

Bowel preparation before colonoscopies may temporarily weaken gut defenses, making it easier for harmful bacteria to cause infection and worsen inflammation.

## Contribution

This study is the first to show that bowel prep increases pathogen susceptibility and worsens colitis in preclinical models.

## Key findings

- Bowel prep with PEG disrupts the gut environment and increases Salmonella infection risk.
- Bowel prep promotes bacterial translocation to organs like the liver and spleen.
- Bowel prep worsens inflammation in a model of chemically induced colitis.

## Abstract

In the United States, an estimated 14 million colonoscopies are performed yearly, each requiring patients to undergo bowel preparation, a laxative cleansing of the intestine’s luminal contents. Despite its widespread use, the effects of bowel preparation on gut physiology and susceptibility to pathogens remain poorly understood, particularly in individuals with compromised gut health. Using mouse and in vitro models, we find that bowel preparation with the laxative polyethylene glycol rapidly disrupts the gut, transiently increasing susceptibility to infection by Salmonella Typhimurium, including a non-motile mutant, and by gut pathobionts derived from ulcerative colitis microbiota. Bowel preparation also facilitates bacterial translocation to extraintestinal sites (mesenteric lymph nodes, liver, and spleen) and exacerbates inflammation in a chemically induced colitis model. Although these findings are preclinical, they suggest that bowel preparation may have underappreciated risks in vulnerable populations and warrant further clinical investigation.

•Bowel preparation with PEG transiently disrupts the mouse gut environment•Susceptibility to Salmonella Typhimurium infection is increased post bowel prep•Chemically induced colitis symptoms are exacerbated post bowel prep

Bowel preparation with PEG transiently disrupts the mouse gut environment

Susceptibility to Salmonella Typhimurium infection is increased post bowel prep

Chemically induced colitis symptoms are exacerbated post bowel prep

Bowel preparation is a widely used intensive laxative cleansing of the gut prior to colonoscopy. Clayton, Porter et al. demonstrate that this process rapidly and transiently disrupts the gut environment, increasing susceptibility to pathogen infection and exacerbating colitis in an IBD model.