Researchers have learned more about how beneficial bacteria in the gut microbiome can help protect against infection. The study also suggested that the right diet can improve the health of the microbiome, to boost its infection-fighting abilities. The findings have been reported in Nature Microbiology.
Some bacteria that can cause serious infections, including some Enterobacteriaceaesuch as Klebsiella pneumoniae, Esherichia coli, and Shigella, are a normal part of the human gut microbiome, as long they exist at relatively low levels compared to other microbes. When the levels of these potential pathogens get too high, they can cause inflammation, infection, illness, and diseases that are sometimes life-threatening.
Scientists have now used computational tools to assess the compositions of the gut microbiomes of more than 12,000 people from 45 countries. This work indicated that the composition or signature of a gut microbiome can predict how likely it is that a person will host Enterobacteriaceae. The findings were largely consistent among different health states and geographic locations.
Around 135 species of gut microbes were also identified that are usually found when Enterobacteriaceae species are lacking. Thus, these microbial species may be protecting against Enterobacteriaceae infections. One group in particular, called Faecalibacterium, are likely especially beneficial. These microbes generate short chain fatty acids (SCFAs) when they break dietary fiber down in the gut. Many studies have linked SCFAs to better health outcomes, and these SCFA-generating microbes also appear to shield carriers from Enterobacteriaceae.
These findings emphasize the importance of eating enough fiber, which can boost the health and proliferation of beneficial and protective microbes. However, the study authors noted that probiotics are unlikely to have a direct effect on the gut microbiome, and probably cannot help in this area.
“Our results suggest that what we eat is potentially very important in controlling the likelihood of infection with a range of bacteria, including E.coli and Klebsiella pneumoniae, because this changes our gut environment to make it more hostile to invaders,” suggested senior study author Dr. Alexandre Almeida of the University of Cambridge. “By eating fiber in foods like vegetables, beans and whole grains, we can provide the raw material for our gut bacteria to produce short chain fatty acids - compounds that can protect us from these pathogenic bugs.”
The study has also expanded our understanding of the gut microbiome and its complexity. There were 172 gut microbe species that were found to coexist with Enterobacteriaceae. Since these microbes can generally eat the same stuff, it's been thought that the good bacteria would outcompete the bad ones. However, this work has shown otherwise; they can live together.
This suggests that probiotics won't reduce the levels of harmful bacteria, and that diet modifications may be more helpful.
“This study highlights the importance of studying pathogens not as isolated entities, but in the context of their surrounding gut microbiome,” added first study author Dr. Qi Yin, a visiting researcher at the University of Cambridge.
Sources: University of Cambridge, Nature Microbiology
