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Validation of the Osteomyelitis Induced by Methicillin-Resistant Staphylococcus aureus (MRSA) on Rat Model with
Young Suk Choi1,2, Dae Sung Ham2,3, Ji Yun Lim2,3
1Department of Biology, Soonchunhyang University, Soonchunhyang-ro, Sinchang-myeon, Asan-si, Chungcheongnam-do, 31538, Republic of Korea.
Background:
Osteomyelitis resulting from bacterial strains, such as methicillin-resistant Staphylococcus aureus (MRSA) that are resistant to multiple drugs, brings further clinical challenges. There is currently no model of osteomyelitis induced by MRSA using rats with calvaria defects. So, We induced osteomyelitis in rat models with the calvaria bone defect.
Methods:
The rats were randomly divided into six groups according to inoculation dose levels, which ranged from 6 × 100 to 6 × 105 CFU/5 µl. Bone tissues were retrieved from all rats used in the study and assessed using histology, microbiology, and radiobiology 4 weeks after surgery to evaluate the relationship between inoculation dose and infectivity.
Results:
In Histological results, high levels of inflammatory responses, bone necrosis, and bacteria were observed in treatment groups G3 to G5. In IHC staining, high levels of cox-2 expression were observed in treatment groups G3. Microbiological observations also indicated that significantly higher numbers of CFUs were found in G3 to G5. In radiography results, the bone mineral density in G3 to G5 was significantly higher than in the control group, G1, and G2. Our results indicate that an inoculating dose of 6 × 103 CFU/5 μl is sufficient to induce the development of osteomyelitis in rat models.
Conclusion:
This study suggests that the minimum dose (6 × 103 CFU/5 µl) can induce osteomyelitis in calvaria rat model. This can offer information and ability of more accurately modeling osteomyelitis and simulating the challenge of osteomyelitis treat.
Insights
A new rat model for osteomyelitis, caused by methicillin-resistant Staphylococcus aureus (MRSA), was developed. A minimum bacterial dose of 6 × 10^3 CFU/5 μl successfully induced osteomyelitis in calvaria defects.
Area of Science:
- Biomedical Engineering
- Infectious Diseases
- Surgical Innovation
Background:
- Osteomyelitis presents significant clinical challenges, particularly when caused by multidrug-resistant bacteria like methicillin-resistant Staphylococcus aureus (MRSA).
- Existing models for studying MRSA-induced osteomyelitis in rats with calvaria defects are lacking.
- This study addresses the need for a reliable animal model to investigate MRSA osteomyelitis.
Purpose of the Study:
- To establish and validate a rat model of osteomyelitis using a calvaria bone defect.
- To determine the minimum infectious dose of MRSA required to induce osteomyelitis in this model.
- To provide a platform for studying MRSA osteomyelitis pathogenesis and treatment.
Main Methods:
- Osteomyelitis was induced in rat calvaria bone defects using varying doses of MRSA (6 × 10^0 to 6 × 10^5 CFU/5 μl).
- Rats were divided into six groups based on inoculation dose.
- Bone tissues were analyzed using histology, immunohistochemistry (IHC), microbiology (CFU counts), and radiography 4 weeks post-surgery.
Main Results:
- Histological examination revealed inflammatory responses, bone necrosis, and bacterial presence in groups receiving higher MRSA doses (G3-G5).
- IHC staining showed elevated cyclooxygenase-2 (COX-2) expression in group G3.
- Microbiological analysis confirmed significantly higher CFU counts in groups G3-G5.
- Radiography indicated increased bone mineral density in groups G3-G5 compared to controls (G1, G2).
Conclusions:
- An inoculation dose of 6 × 10^3 CFU/5 μl was identified as the minimum effective dose for inducing osteomyelitis in the calvaria rat model.
- This validated model allows for more accurate simulation of osteomyelitis challenges.
- The model provides a valuable tool for future research into osteomyelitis treatment strategies.
