The mechanisms driving gut bacterial imbalance.
During episodes of intestinal inflammation – which can occur during IBD and gastrointestinal infections and cancers – the composition of these gut microbial communities is radically disturbed.
“Beneficial bacteria begin to dwindle in numbers as less beneficial, or even harmful, bacteria flourish,” said Ms. Hughes. “This imbalance of microbiota is believed to exacerbate the inflammation.”
A healthy gut is devoid of oxygen. The beneficial bacteria that live there are well-adapted to the low-oxygen environment and break down fiber through fermentation. Unlike these beneficial bacteria, potentially harmful E. coli grow better in high-oxygen environments.
“Inflammation changes the environment so that it is no longer perfect for the commensal anaerobes, but perfect for opportunistic E. coli, which basically wait for an ‘accident’ like inflammation to happen,” Dr. Winter explained.
The increased availability of oxygen during inflammation helps E. coli thrive in an inflamed gut through a metabolic “trick,” Ms. Hughes said.
“Through respiration, the abundant waste products generated by the beneficial microbes can be ‘recycled’ by commensal E. coli – which do not grow well on fiber – and turned into valuable nutrients, thus fueling a potentially harmful bloom of the E. coli population,” she explained.
“If we interfere with the production of waste products by the beneficial commensal bacteria, then we impede their metabolism, which causes them to grow more slowly and throw off the entire ecosystem,” Dr. Winter said. “The most effective strategy may be to inhibit commensal E. coli‘s unique metabolism to avoid the bloom and negative impacts.”