Stress alters our gut microbiome leading to increased colonic inflammation during infections.

The mutualistic (friendly) bacteria in our gut is vital for defences against infections because it works in concert our immune system to kill and inhibit the growth of harmful bacteria.

For sometime it has been proposed stress can alter the populations of friendly bacteria leading to vulnerability to acute or chronic infections and inflammation. People with  Crohn’s or Ulcerative Colitis have significantly different bacteria populations to healthy people , but scientists are still not sure how much the alterations of gut bacteria has to do with the progression of these diseases. This study below might help find the answer.

The commensal microbiota exacerbate infectious colitis in stressor-exposed mice

• Germfree mice were colonized with microbiota from stressor-exposed or control mice.
• Newly colonized mice were infected with the colonic pathogen Citrobacter rodentium.
• Colonization with microbiota from stressed donors increased colonic inflammation.
• Stressor-induced effects on the microbiota directly affect mucosal immunity.


Study conclusion: This study demonstrates that the commensal microbiota directly contribute to excessive inflammatory responses to C. rodentium during stressor exposure, and may help to explain why gastrointestinal disorders are worsened during stressful experiences.


This study revealed the stressed mice guts did not have an important species of friendly bacteria called Bifidobacterium,  but in mice not exposed to stress there was bifidobacterium present. It is is suggest that the absence of  bifidobacterium caused a more severe inflammatory response.

Bifidobacterium coevolved with us. It is important for immunity, energy, metabolic process and mood. Studies like this help us understand the benefits of maintaining a healthy gut microbiome and perhaps they will help us develop more effective treatments for gastrointestinal complaints.

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