Crohn’s Disease and Intestinal Bacteria

Intestinal bacteria play an important role in the development of Crohn’s disease. External factors, such as gastroenteritis and antibiotic use, can lead to changes in the composition of intestinal bacteria resulting in an increased risk of developing Crohn’s disease.


Oberc, A., & Coombes, B. K. (2015). Convergence of External Crohn’s Disease Risk Factors on Intestinal Bacteria. Frontiers in Immunology, 6, 558. 

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What is this research about?

Crohn’s disease (CD) is a disorder that affects the digestive system. CD is becoming increasingly common in many high-income countries. Although genetics are known to play a role in the development of CD, it cannot fully account for the sharp rise in CD over the past 40 years. Environmental exposures are likely having a significant impact and this research examines gastroenteritis and antibiotic use as key risk factors that can lead to the development of CD. In addition, the effects of CD on the microbial species that reside in the gut are discussed.

What did the researchers do?

The researchers provide a review of the literature and highlight the main themes that are beginning to emerge from research into CD. They examine studies that compare the composition of gut bacteria in healthy individuals and patients with CD. In addition, infectious gastroenteritis and antibiotic use are reviewed as risk factors for the development of CD.

What did the researchers find?

Individuals with CD have significant changes in the types of microbes that populate their gut. There is a decreased abundance and diversity of a microbial class known as Firmicutes as well as an increased abundance of Proteobacteria. A bacterial species known as adherent invasive E.coli is a dominant species present in many individuals with CD. This bacterial species is resistant to immune system defenses and also many antibiotics. Currently there are no studies that have examined the effectiveness of targeting this class of bacteria in treatments for CD.
Gastroenteritis is a bacterial infection usually arising from food poisoning that results in inflammation in the intestinal lining and studies have shown that patients with gastroenteritis have an increased risk of developing CD. Antibiotics are known to negatively affect the bacterial species that populate the gut and several studies have linked exposure to antibiotics with CD. While gastroenteritis and antibiotic use are associated with CD, neither can be considered a direct cause of CD on their own.

How can you use this research?

Physicians and other health care providers can use this review to gain an understanding of the potential microbial contributions to CD. 

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