Healthy gut bacteria reduces hospitalizations due to infections, study finds

In a recently published study, Lancet Microorganism, Researchers investigated the association between gut microbiota composition and risk of hospitalization due to infectious diseases. Using 16S rRNA sequencing, we characterized gut bacterial diversity and abundance in two large, independent population-based European cohorts.

The findings reveal that the composition of the gut microbiota, particularly the abundance of butyrate-producing bacteria, may protect against serious infections requiring hospitalization.

study: Association between butyrate-producing gut bacteria and risk of infectious hospitalization: results from two observational population-based microbiome studiesImage credit: Drazen Zigic/Shutterstock.com

background

Despite great advances in modern medicine, infectious diseases place a significant burden on the population's healthcare: the Global Burden of Disease Study (2019) estimates that approximately 25% of annual mortality can be attributed to severe infectious diseases.

These findings suggest that current prevention and treatment methods are insufficient to limit the impact of infectious diseases and that new strategies must be discovered to prevent infections severe enough to lead to hospitalization and death.

Recent studies by these authors and others suggest that the human gut microbial composition may be intrinsically linked to immunity to infection.

A growing number of studies have reported that most patients with severe infections have gut microbial dysbiosis at the start of their hospital stay (before treatment begins, which exacerbates gut dysbiosis).

Mouse models support these observations, linking infection with a decrease in gut anaerobic bacteria and a concomitant increase in potentially pathogenic gut microbiota.

Unfortunately, data from humans are primarily observational, and externally validated and geographically controlled results are rarely found in the literature.

About the Research

A previous study by these authors reported an association between a decrease in butyrate-producing gut bacteria and an increased risk of respiratory infections in human patients.

This study builds on that work and hypothesizes that the composition and relative abundance of gut microbes may influence an individual's susceptibility to severe infections requiring hospitalization.

Study methods and reporting of results conformed to the Strengthening the Organizing and Reporting of Microbiome Research (STORMS) reporting guidelines.

Data for this study were derived from two independent large European-based population cohorts: the Netherlands-based HELIUS study and the Finland-based FINRISK 2002 study. Both cohorts were nationwide prospective studies of hospitalization and mortality.

HELIUS consists of the Dutch population (aged 18–70 years) in Amsterdam, stratified by ethnicity, and FINRISK includes a random sample of adults (aged 25–74 years) from six regions in Finland.

Data were collected by questionnaires, physical examinations and assessment of stool samples. All data were linked to participants' medical and demographic records and used to determine the primary outcome (hospitalisation or mortality).

Following the Global Microbiome Project protocol, fecal samples were subjected to 16S rRNA sequencing (Illumina) to determine gut bacterial composition, alpha diversity, and relative abundance (Shannon diversity index).

Differences in community composition between participants who required hospitalization and those who did not were calculated using permutational multivariate analysis of variance (ANOVA) with the Analysis of Microbiome Composition with Bias Correction (ANCOM-BC) correction.

research result

The total number of participants in both cohorts was 10,699 (HELIUS – 4,248, FINRISK – 6,451).

The gut microbial composition of the entire cohort was mainly composed of Firmicutes (Bacillota) and Bacteroidetes with a mean relative abundance of 65.9% and 24.1%, respectively. 3.6% of the HELIUS cohort and 7.0% of the FINRISK study suffered from severe infections during the study and subsequent follow-up period (6 years). Most commonly, these were lower respiratory tract infections.

In the result groups (severe infection group and healthy group), the separation in gut bacterial community composition was confirmed by permutation test, Veilloneira and Streptococcus There is a significant increase in relative abundance in the hospitalization or death groups.

In contrast, healthy participants Butyrivibrio, Anaerobic butyrate-producing obligate microorganism.

“…these data indicate that in two independent cohorts, the baseline gut microbiota composition differed between participants who were hospitalized with infection during follow-up and those without infection-related hospitalization, similarly driven by an increase in Veillonella and a decrease in the obligate anaerobe Butyrivibrio.”

Cox proportional hazards ratio estimation revealed that the relative abundance of butyrate-producing bacteria directly contributed to a reduced risk of severe infection, with a cause-specific hazard ratio (csHR) of 0.75 for every 10% increase in the relative abundance of these bacteria.

These results were unchanged after adjustment for potential confounding factors (gender, age, ethnicity, alcohol consumption, smoking, and comorbidities) and microbiome composition characteristics.

Together, these results highlight that the relative abundance of butyrate-producing bacteria is directly associated with a reduced risk of infections requiring hospitalization or leading to death.

Participants with a body mass index (BMI) of over 30 km/m² The exception was that BMI was the only confounding variable that altered these findings: simply put, a BMI indicative of obesity essentially eliminated the observed associations.

Conclusion

This study highlights that in two large, independent European cohorts investigated, the abundance of anaerobic butyrate-producing gut bacteria is associated with a significantly reduced risk of future severe infections.

These findings suggest that the gut microbiota is a potentially easily modifiable risk factor for preventing infections requiring hospitalization.

If these results are validated through intervention studies, they may inform clinicians and policy makers in the future about the best dietary interventions to limit human susceptibility to systemic infection and prevent population-wide transmission.