Related Experiment Video
Updated: Mar 3, 2026
A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection
Published on: February 28, 2019
Inflammatory responses and histopathological changes in a mouse model of Staphylococcus aureus-induced bloodstream
Dan Wu1, Shusheng Zhou, Shijing Hu
1Nanjing First Hospital, Nanjing Medical University, Nanjing, China. wudan7451321@26.com.
Introduction:
Staphylococcus aureus-induced bloodstream infections (BSIs) remain a prevalent clinical challenge and the underlying pathogenesis is still poorly understood. The aim of this study was to investigate the inflammatory responses and histopathological changes in BSIs in mice.
Methodology:
Male C57BL/6 mice were inoculated with S. aureus intravenously to induce BSIs. The survival rate, weight loss, and murine sepsis scores (MSS) were monitored in BSI and phosphate-buffered saline (PBS) control mice. Blood samples and tissue homogenates were plated on agar plates to determine the bacterial burden. Inflammatory proteins and cytokines were determined by enzyme-linked immunosorbent assay (ELISA) kits. Histopathologic changes were assessed by pathological inflammation score (PIS) and macroscopic and microscopic examinations.
Results:
BSI mice induced by 4.5 × 108 CFU/mL S. aureus showed ~70% survival rate, higher sepsis scores, significantly decreased body weight, elevated levels of white blood cell (WBC) counts, C-reactive protein (CRP), procalcitonin (PCT), interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. Prominent correlations were found between elevated CRP and PCT levels as well as among IL-1β, IL-6, and TNF-α. Pathological changes and higher PIS were also observed in BSI mice.
Conclusions:
Our results demonstrate that inflammatory proteins (PCT and CRP) and cytokines (IL-6, IL-1β and TNF-α) play an important role in the inflammatory responses and histopathological changes in S. aureus-induced BSIs.
Insights
Staphylococcus aureus bloodstream infections trigger significant inflammatory responses and tissue damage. Key inflammatory markers like procalcitonin and cytokines are crucial in understanding these severe bacterial infections.
Area of Science:
- Infectious Diseases
- Immunology
- Pathology
Background:
- Staphylococcus aureus bloodstream infections (BSIs) present a significant clinical challenge.
- The pathogenesis of S. aureus BSIs is not fully understood.
- Investigating inflammatory responses and histopathological changes is crucial.
Purpose of the Study:
- To investigate the inflammatory responses in S. aureus-induced BSIs in mice.
- To analyze histopathological changes associated with S. aureus BSIs.
- To identify key inflammatory markers involved in S. aureus pathogenesis.
Main Methods:
- Male C57BL/6 mice were intravenously inoculated with S. aureus to induce BSIs.
- Survival, weight loss, sepsis scores, and bacterial burden were monitored.
- Inflammatory proteins (CRP, PCT) and cytokines (IL-1β, IL-6, TNF-α) were quantified using ELISA.
- Histopathological changes were assessed using pathological inflammation scores (PIS) and macroscopic/microscopic examinations.
Main Results:
- S. aureus BSIs led to approximately 70% survival, increased sepsis scores, and decreased body weight.
- Elevated white blood cell counts, C-reactive protein (CRP), procalcitonin (PCT), and cytokines (IL-1β, IL-6, TNF-α) were observed.
- Significant correlations were found between CRP/PCT and between IL-1β/IL-6/TNF-α.
- BSI mice exhibited pathological changes and higher PIS.
Conclusions:
- Inflammatory proteins (PCT, CRP) and cytokines (IL-6, IL-1β, TNF-α) are critical in S. aureus-induced BSIs.
- These markers play a significant role in the observed inflammatory responses.
- The study highlights the contribution of these factors to histopathological changes in S. aureus BSIs.
