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Updated: Jan 8, 2026
A Neonatal Imaging Model of Gram-Negative Bacterial Sepsis
Published on: August 12, 2020
Multiplexed longitudinal analysis of the cellular and microbial dynamics of acute polymicrobial sepsis in mice
Tori E Peacock1, Kenny Johnson1, Abhinav R Cheedipudi1
1Department of Pathology, Microbiology, and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States.
Introduction:
Acute polymicrobial sepsis is a life-threatening emergency caused by the body's immune response to bloodstream infection by two or more microbes. Early detection and management of sepsis have been the focus of global survey programs, driven by its association with hospital readmissions and long-term adverse health outcomes.
Methods:
Animal models are essential tools for studying mechanisms of sepsis pathogenesis and the only way to empirically dissect the acute phase of disease. With this in mind, the goal of the current study was two-fold: to demonstrate the feasibility of performing multiplexed longitudinal assessment of acute sepsis pathogenesis and to emphasize the granularity with which acute sepsis can be studied using this method. Using the fecal suspension test (FST) model of acute polymicrobial sepsis in C57BL/6 mice we simultaneously characterize hematological, immunological, and microbiological aspects of acute sepsis induction.
Results:
Our data shows that high dimensional flow cytometry paired with flow-based plasma cytokine measurements captures the dynamic shift from pro-inflammatory to anti-inflammatory immune responses during an acute septic event; highlighting the role of emergency myelopoiesis in this process. Additionally, myeloid cell heterogeneity is characterized and strongly implicates the emergence of myeloid derived suppressor like cells (MDSC-like cells) as central to this switch. Furthermore, we demonstrate a 16S-based method for studying the blood biome that allows for discrimination between endogenous (bacterial DNAemia) and exogenous (actively growing bacteria in blood) sources of microbial DNA. Using this approach, we demonstrate that polymicrobial sepsis in our model is due to outgrowth of Enterococcus and Staphylococcus; two genera of bacterial pathobionts commonly observed in human sepsis patients. Finally, using several assessments of disease severity, we demonstrate stratification of septic mice into survivors and non-survivors and show how pre-septic immune assessment can be used to identify potential biomarkers of sepsis risk.
Discussion:
Collectively, the approach we describe simultaneously reduces research animal use, strengthens scientific rigor, provides a pre-clinical platform for biomarker discovery and the study of therapeutic interventions, and most importantly advances our ability to study the acute phase of sepsis that carries a high mortality rate and is difficult to prospectively study in humans.
Insights
This study presents a new method for analyzing acute polymicrobial sepsis in mice. It tracks immune responses and bacterial changes, offering a more detailed understanding of sepsis progression and potential biomarkers.
Area of Science:
- * Immunology
- * Microbiology
- * Animal models
Background:
- * Acute polymicrobial sepsis is a life-threatening condition requiring early detection and management.
- * Global health initiatives focus on sepsis due to its links to hospital readmissions and long-term health issues.
- * Animal models are crucial for dissecting sepsis pathogenesis during its acute phase.
Purpose of the Study:
- * To demonstrate the feasibility of multiplexed, longitudinal assessment of acute sepsis pathogenesis.
- * To highlight the detailed insights obtainable through this advanced study method.
- * To characterize hematological, immunological, and microbiological aspects of sepsis induction in a mouse model.
Main Methods:
- * Utilized the fecal suspension test (FST) model in C57BL/6 mice.
- * Employed high-dimensional flow cytometry and plasma cytokine measurements.
- * Incorporated 16S rRNA gene sequencing for blood microbiome analysis.
Main Results:
- * Observed a dynamic shift from pro-inflammatory to anti-inflammatory immune responses, involving myeloid-derived suppressor-like cells.
- * Identified outgrowth of *Enterococcus* and *Staphylococcus* as causative agents in polymicrobial sepsis.
- * Stratified septic mice into survivors and non-survivors, identifying potential pre-septic biomarkers for sepsis risk.
Conclusions:
- * The described approach reduces animal use and enhances scientific rigor.
- * Provides a preclinical platform for biomarker discovery and therapeutic intervention studies.
- * Advances the study of the acute phase of sepsis, which is challenging to investigate prospectively in humans.
