A rabbit osteomyelitis model to simulate multibacterial war wound infections

Area of Science:

• Military medicine
• Infectious diseases
• Wound healing

Background:

• Military caregivers face challenges with multidrug-resistant infections in extremity wounds.
• Common resistant strains include methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae (KP), Pseudomonas aeruginosa (PA), and Acinetobacter baumannii (AB).

Purpose of the Study:

• To adapt an existing osteomyelitis model for simulating infected extremity wounds, specifically blast wounds, for antibiotic testing.
• To evaluate the efficacy of inducing osteomyelitis in rabbits using single and multiple strains of multidrug-resistant bacteria.

Main Methods:

• New Zealand White Rabbits (n=95) were used, with induced tibia trauma followed by inoculation with specific bacteria or combinations.
• Infection was induced using MRSA, KP, PA, and AB, alone and in multibacterial combinations.
• Osteomyelitis induction rates and radiographic improvements were assessed.

Main Results:

• Acinetobacter baumannii, Klebsiella pneumoniae, or Pseudomonas aeruginosa alone at 10(7) CFUs/mL effectively induced osteomyelitis.
• A combination of AB (10(7) CFUs/mL)/KP (10(7) CFUs/mL)/PA (10(7) CFUs/mL)/MRSA (10(5) CFUs/mL) achieved a 100% osteomyelitis induction rate.
• Limited radiographic improvement was observed in only one mono-bacterial and one multibacterial group at 8 weeks.

Conclusions:

• The rabbit osteomyelitis model is adaptable for studying infected blast wounds relevant to veterans.
• This study demonstrates the model's capability in simulating multibacterial infections with multidrug-resistant organisms.