Analysis of Porcine Model of Fecal-Induced Peritonitis Reveals the Tropism of Blood Microbiome.

Hwi Hyun,Min Seok Lee,Joo H Kang,Hajin Kim,Inwon Park,Seonghye Kim,Seongmin Yun,Dong-Hyun Jang,Hwa Soo Ko,Taejoon Kwon,Jae Hyuk Lee

doi:10.3389/fcimb.2021.676650

Abstract

Recent studies have suggested the existence of a blood microbiome in the healthy host. However, changes in the blood microbiome upon bloodstream infection are not known. Here, we analyzed the dynamics of the blood microbiome in a porcine model of polymicrobial bacteremia induced by fecal peritonitis. Surprisingly, we detected bacterial populations in the bloodstream even before the infection, and these populations were maintained over time. The native blood microbiome was notably taxonomically different from the fecal microbiome that was used to induce peritonitis, reflecting microbial tropism for the blood. Although the population composition after the infection was similar to that of the native blood microbiome, new bacterial strains entered the bloodstream upon peritonitis induction as clinical symptoms relevant to sepsis developed. This indicates that the bacteria detected in the blood before peritonitis induction were derived from the blood rather than a contamination. Comparison of the functional pathways enriched in the blood and fecal microbiomes revealed that communication and stress management pathways are essential for the survival of the blood microbiome.

Highlights

Bloodstream infection (BSI) is defined as a medical condition, in which viable bacteria or fungi are present in the bloodstream (Viscoli, 2016)
In the analysis presented above, we confirmed that new bacterial phyla have emerged into the bloodstream after peritonitis induction, and the populations of the native blood microbiome are notably different in each animal
Microbiota transmission between organs, presumably via the bloodstream, has been reported in previous studies (Dominy et al, 2019; Massier et al, 2020; Sookoian et al, 2020). Based on these studies, it is unclear how the blood microbiome is maintained because these studies provide only a “snapshot” view of a single point in time

Summary

Introduction

Bloodstream infection (BSI) is defined as a medical condition, in which viable bacteria or fungi are present in the bloodstream (Viscoli, 2016). BSI is a major threat to human health, as it can cause sepsis and organ dysfunction (Cecconi et al, 2018). A survey of the incidence of BSI in America and Europe during the years 1974-2008 reported rates between 80 and 189 per 100,000 individuals per year; this number has increased in recent years (Laupland, 2013; Laupland et al, 2020). Longitudinal Analysis of Blood Microbiome deaths per year in North America and 157,000 deaths per year in Europe (Goto and Al-Hasan, 2013)

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Conclusion