Recent studies conducted with two large European patient cohorts have shown that a 10% increase in butyrate-producing bacteria in a patient’s gut resulted in a 14-25% decrease in the risk of hospitalization due to infection. This study, presented at the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID 2024) in Barcelona, Spain (27-30 April), was led by Robert Kullberg from the University Medical Center Amsterdam, Netherlands, and colleagues.
Changes in the microbiota often occur in patients admitted to the hospital for severe infections, and preclinical models have shown that anaerobic butyrate-producing gut bacteria protect against systemic infections. These bacteria were studied because they are often missing in patients hospitalized for severe infections and because butyrate can have a protective effect in various intestinal diseases, apart from infections.
However, the link between microbiota disruption and increased susceptibility to severe infections in humans remains unclear. In this study, the authors examined the relationship between the baseline gut microbiota and the risk of future infection-related hospitalizations in two large population-based cohorts from the Netherlands (derivation: HELIUS) and Finland (validation: FINRISK 2002).
The gut microbiota was characterized by sequencing the DNA of bacteria to identify the different types of bacteria present in the participants‘ stool samples. The authors measured the composition, diversity, and relative frequency of butyrate-producing bacteria in the microbiota. The primary endpoint was hospitalization or mortality due to an infectious disease during the follow-up period of 5-7 years after stool sample collection, based on national registry data. The authors then examined correlations between microbiota and infection risk using computer models. Additional statistical models were used to adjust for variables such as demographics, lifestyle, antibiotic exposure, and comorbidities.
The researchers analyzed the gut microbiota of 10,699 participants (4,248 from the Netherlands and 6,451 from Finland). A total of 602 participants (Netherlands: n=152; Finland: n=450) were hospitalized or died due to infections (mainly community-acquired pneumonia) during the follow-up period.
The composition of the gut microbiota of these hospitalized/deceased participants differed from the composition of participants who were not hospitalized for infections. Specifically, a 10% higher frequency of butyrate-producing bacteria was associated with a lower risk of hospitalization due to infections – 25% lower in participants from the Dutch cohort and 14% lower in the Finnish cohort. All types of infections were assessed collectively, not a specific one. These associations remained unchanged after adjusting for demographics, lifestyle, antibiotic exposure, and comorbidities.
The authors state: „The composition of the gut microbiome, particularly colonization with butyrate-producing bacteria, is associated with protection against hospitalizations related to infectious diseases in the general population in two independent European cohorts. Further studies should investigate whether microbiome modulation can reduce the risk of severe infections.“
Additional analyses are needed before patient studies can begin, according to the authors. One of the challenges is that butyrate-producing bacteria are strictly anaerobic (meaning they respire without oxygen consumption and cannot tolerate oxygen), making it very difficult to transport viable bacteria into the gut. Several research groups are working to address these challenges.
Source:
European Congress of Clinical Microbiology and Infectious Diseases (ECCMID 2024)