Inflammatory responses and histopathological changes in a mouse model of Staphylococcus aureus-induced bloodstream infections

  • Dan Wu Nanjing First Hospital, Nanjing Medical University, Nanjing, China
  • Shusheng Zhou Affiliated Provincial Hospital of Anhui Medical University, Hefei, China
  • Shijing Hu Affiliated Provincial Hospital of Anhui Medical University, Hefei, China
  • Bao Liu Affiliated Provincial Hospital of Anhui Medical University, Hefei, China

Abstract

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.

Author Biographies

Dan Wu, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
Department of Emergency Medicine
Shusheng Zhou, Affiliated Provincial Hospital of Anhui Medical University, Hefei, China
Department of Critical Care Medicine
Shijing Hu, Affiliated Provincial Hospital of Anhui Medical University, Hefei, China
Department of Critical Care Medicine
Bao Liu, Affiliated Provincial Hospital of Anhui Medical University, Hefei, China
Department of Critical Care Medicine
Published
2017-04-30
How to Cite
Wu D, Zhou S, Hu S, Liu B (2017) Inflammatory responses and histopathological changes in a mouse model of Staphylococcus aureus-induced bloodstream infections. The Journal Of Infection In Developing Countries 11 (04): 294-305. https://doi.org/10.3855/jidc.7800
Section
Original Articles

Keywords

Staphylococcus aureus; bloodstream infections; inflammation; cytokines; Histopathology