Model of experimental chronic osteomyelitis in rats

Area of Science:

• Veterinary Medicine
• Infectious Diseases
• Skeletal Biology

Background:

• Chronic osteomyelitis is a persistent bone infection that is challenging to treat.
• Developing reliable animal models is crucial for studying osteomyelitis pathogenesis and evaluating therapies.

Purpose of the Study:

• To establish and characterize a Sprague-Dawley rat model for chronic osteomyelitis.
• To assess the efficacy of different inoculation methods and evaluate antimicrobial treatment responses.

Main Methods:

• Osteomyelitis was induced in Sprague-Dawley rats by implanting Staphylococcus aureus and sodium morrhuate into tibiae using microdrilling or needle injection.
• Histopathological analysis, microbiological quantification (CFU counts), and roentgenograms were used to assess disease development and chronicity.
• Infected rats were treated with oxacillin or ceftriaxone to evaluate therapeutic responses.

Main Results:

• Microdrilling resulted in a higher osteomyelitis incidence (81%) compared to needle injection (51%).
• The model demonstrated chronic infection with stable S. aureus counts over 70 days, accompanied by anemia and weight loss.
• Roentgenograms showed a strong correlation with bacterial load (r2 = 0.80).
• Antibiotic treatment reduced bacterial counts but did not reliably sterilize the infected bone, indicating resistance.

Conclusions:

• The described Sprague-Dawley rat model effectively replicates chronic osteomyelitis.
• This model is suitable for studying osteomyelitis pathogenesis and testing novel therapeutic strategies.
• The model exhibits resistance to prolonged antimicrobial therapy, highlighting the need for advanced treatment approaches.