Enterococcus faecalis exacerbates burn injury-induced host responses in rats

Area of Science:

• Critical care medicine
• Infectious disease
• Surgical pathology

Background:

• The pathophysiology of burn injuries complicated by Gram-positive infections, such as Enterococcus faecalis, is not well understood.
• Existing models do not fully capture the combined effects of burn trauma and bacterial infection.

Purpose of the Study:

• To develop and validate an in vivo rat model simulating burn injury combined with intra-abdominal Enterococcus faecalis infection.
• To investigate the synergistic pathophysiological consequences of combined burn injury and E. faecalis inoculation.

Main Methods:

• Sprague-Dawley rats were assigned to four groups: control, burn injury only, E. faecalis inoculation only, and combined burn injury with E. faecalis inoculation.
• Mortality rates, metabolic acidosis, respiratory status, and hemodynamic parameters were monitored.
• Intestinal microvascular permeability to albumin was assessed on days 1 and 2 post-intervention.

Main Results:

• The combined burn injury and E. faecalis group exhibited significantly higher mortality (25% on day 1, 60% on day 2) compared to other groups.
• Group 4 developed metabolic acidosis, respiratory alkalosis (day 1), and later metabolic/respiratory acidosis with a hypodynamic state (day 2).
• Increased intestinal microvascular permeability to albumin in the combined group correlated with observed metabolic and hemodynamic alterations.

Conclusions:

• Combined burn injury and E. faecalis infection create a detrimental cycle, worsening intestinal integrity and leading to severe systemic derangements.
• E. faecalis plays a crucial role in initiating this vicious cycle following burn injury.
• The developed rat model effectively demonstrates the adverse effects of combined burn injury and Gram-positive infection.