Acinetobacter baumannii is not associated with osteomyelitis in a rat model: a pilot study
Stefan Collinet-Adler1, Carlos A Castro, Charles Gerald T Ledonio
1Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Tufts University, Boston, MA, USA.
Clinical Orthopaedics and Related Research
|July 30, 2010
Summary
Multidrug-resistant Acinetobacter baumannii (MDR AB) showed low virulence in rat bone defects, with Staphylococcus aureus (SA) dominating polymicrobial infections. MDR AB alone did not cause osteomyelitis, suggesting it may not contribute to bone infections.
Area of Science:
- Orthopedics
- Infectious Diseases
- Microbiology
Background:
- Multidrug-resistant Acinetobacter baumannii (MDR AB) is frequently found in infected segmental bone defects from combat trauma.
- While MDR AB poses challenges in visceral infections, its control in combat-related osteomyelitis is more common.
Purpose of the Study:
- To investigate the virulence of MDR AB in a rat model of segmental bone defects.
- To assess the impact of MDR AB alone and in combination with Staphylococcus aureus (SA) on bone defect infections.
Main Methods:
- Segmental defects were created in 60 rat femurs and inoculated with either MDR AB alone or MDR AB and SA.
- Bacteriology and radiographic assessments were performed at various time points to evaluate bacterial load and bone healing.
Main Results:
- MDR AB exhibited a significant decrease in bacterial load (3- to 5-log) regardless of inoculation type.
- In polymicrobial infections, SA predominated (59/60 animals), while MDR AB was rarely cultured (10/60 animals).
- MDR AB alone did not cause osteolysis; however, osteolysis was observed when SA was present. New bone formation occurred in 67% of defects with MDR AB alone.
Conclusions:
- MDR AB did not appear to cause or contribute to clinically significant osteomyelitis in this pilot study.
- The low virulence of MDR AB may explain the resolution of infections in combat-related bone defects.
- Further research is required to confirm the low virulence of MDR AB and its role in bone formation.
