Findings could open new avenues to lower Crohn's risk in people recovering from infectious diarrhea.
In the mouse gut, infectious diarrhea caused by microbes promotes growth of a certain type of Escherichia coli bacteria and worsens disease severity, according to a new study in PLOS Pathogens. These findings suggest that people with infectious diarrhea whose guts harbor this type of E. coli may be at greater risk for Crohn's disease.
A healthy gut is home to many microbes, but gut bacteria also play a major role in many bowel diseases. People with Crohn's tend to have higher numbers of a type of gut bacteria known as adherent-invasive Escherichia coli (AIEC) in their gut. Crohn's also occurs more often in people who have had acute infectious gastroenteritis (infectious diarrhea) caused by Salmonella or other pathogens. However, the microbial interactions that contribute to Crohn's disease are not well known.
To better understand these microbial interactions, Cherrie Small, at McMaster University in Canada, and colleagues studied the guts of mice. They infected some mice with an AIEC strain collected from a person with Crohn's disease and left some mice uninfected. Then they exposed the mice to additional bacteria that caused acute infectious gastroenteritis.
After exposure to the diarrhea-causing bacteria, mice that had been infected with AIEC experienced greater disease severity, as well as increased growth of AIEC. The researchers concluded that acute infectious gastroenteritis creates an inflammatory environment in the gut that worsens disease severity and promotes AIEC growth.
These findings suggest a potential role for diagnostic tools that could identify people with elevated AIEC who may be at greater risk for Crohn's after experiencing acute gastroenteritis. Because Crohn's disease can take years to develop after acute gastroenteritis, it may also be possible to develop ways of lowering risk in people with AIEC.
"This work," the authors summarize, "addresses how AIEC persists in the inflamed gut and makes a novel connection to a perplexing risk factor in Crohn's disease, which is acute infectious gastroenteritis. Based on this work, AIEC status might be an important measure in the management of Crohn's disease risk in individuals following episodes of food poisoning."
Article: Acute Infectious Gastroenteritis Potentiates a Crohn's Disease Pathobiont to Fuel Ongoing Inflammation in the Post-Infectious Period, Small CL, Xing L, McPhee JB, Law HT, Coombes BK, PLOS Pathogens, doi:10.1371/journal.ppat.1005907, published 6 October 2016.