Why do some people get sepsis while others dont? Scientists point to the gut

Potentially deadly sepsis may be more likely in certain patients due to problems in the gut.Researchers from the Korea Research Institute of Bioscience and Biotechnology’s Infectious Disease Research Center used female mouse models to investigate why sepsis outcomes can vary so dramatically.The study, published in the journal Nature, looked at genetically similar mice with different gut microbiomes.The mice were infected with Acinetobacter baumannii — a highly resilient bacterium that can lead to sepsis.The researchers compared groups of mice with higher and lower survival rates, examining differences in their gut microbiomes, the amount of bacteria in their blood and organs, and other cellular markers, according to the study press release.Although some mice were genetically similar, the more vulnerable mice had a higher concentration of Muribaculaceae bacteria in the gut.

In one comparison, these bacteria made up about 28% of the microbiome in poor surviving mice, but only 0.15% in better surviving mice.Mice with worse survival showed an early and strong inflammatory response, which later led to more bacteria in the blood, lungs and spleen.This suggests that the microbiome causes the immune system to be more reactive, according to the researchers.In the microbiome of mice with worse survival, the researchers also noticed that one strain of bacteria — Sangeribacter muris KT1-3 — was most prominent.

The mice that typically survived at high rates fared much worse when housed with KTI-3 mice, with their survival falling to 10%.This bacterial strain also appeared to worsen inflammation during certain infections, making sepsis more severe.These findings suggest that the gut microbiome can signal how the immune system will react before an infection begins.Andrew Fleming, MD, section chief of Infectious Diseases & Immunology at NYU Langone Hospital, Brooklyn, said it has been “known for years” that gut bacteria and bacterial toxins can be released...