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Updated: Jun 4, 2026
A Novel Method to Determine the Longitudinal Antibacterial Activity of Drug-Eluting Materials
Published on: March 3, 2023
Experimental osteomyelitis caused by methicillin-resistant Staphylococcus aureus treated with a polylactide carrier
Panagiotis Tsiolis1, Evangelos J Giamarellos-Bourboulis, Andreas F Mavrogenis
1Second Department of Orthopaedics, University Medical School, Athens, Greece.
Background:
The effectiveness of a new delivery system consisting of polymerized dilactide (PLA) with incorporated linezolid was investigated in a rabbit model as a means of treating methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis.
Methods:
The PLA-linezolid system was prepared after thorough stirring of PLA with linezolid at a 10:1 ratio. Experimental osteomyelitis was established in 40 rabbits by a modification of the Norden model with MRSA as the test isolate. After a hole had been drilled in the upper right femur, the isolate was inoculated using a thin needle working as a foreign body. At three weeks, the needle was removed and cultured, and the PLA-linezolid system was implanted in half the animals (group B); the remaining half was the control group (group A). Animals were sacrificed at regular intervals; tissue around the site of implantation was examined for pathologic changes and cultured quantitatively.
Results:
The prepared system eluted linezolid in vitro at concentrations much greater than the minimum inhibitory concentration (MIC) of the test pathogen for 11 days. At three weeks after inoculation of the test isolate, all animals had osteomyelitis. By the sixth week, bacterial growth from cancellous bone of group B was significantly lower than that in group A. However, this effect was not maintained until the end of the study (weeks 8 and 10), when the differences in bacterial growth in the two groups were not significant.
Conclusion:
Polymerized dilactide mixed with 10% linezolid achieved partial arrest of the offending pathogen in an experimental model of osteomyelitis caused by MRSA.
Insights
A novel polymerized dilactide (PLA) system with linezolid showed initial promise in treating methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis in rabbits, but long-term effectiveness was not sustained.
Area of Science:
- Biomaterials Science
- Infectious Diseases
- Orthopedic Surgery
Background:
- Osteomyelitis is a challenging bone infection, often caused by difficult-to-treat pathogens like methicillin-resistant Staphylococcus aureus (MRSA).
- Novel drug delivery systems are needed to effectively treat chronic infections and overcome antibiotic resistance.
Purpose of the Study:
- To evaluate the efficacy of a new polymerized dilactide (PLA) delivery system incorporating linezolid for treating MRSA osteomyelitis in a rabbit model.
Main Methods:
- A PLA-linezolid composite was prepared at a 10:1 ratio.
- Experimental MRSA osteomyelitis was induced in rabbits.
- The PLA-linezolid system was implanted in half the rabbits (Group B), with the other half serving as controls (Group A).
- Bone tissue was quantitatively cultured at regular intervals to assess bacterial growth.
Main Results:
- The PLA-linezolid system released linezolid in vitro above the minimum inhibitory concentration for 11 days.
- Bacterial growth in cancellous bone was significantly reduced in the PLA-linezolid group compared to controls at week 6.
- This significant reduction in bacterial growth was not maintained at weeks 8 and 10.
Conclusions:
- The polymerized dilactide-linezolid system demonstrated partial control of MRSA in an experimental osteomyelitis model.
- Further research is needed to optimize delivery systems for sustained therapeutic effects in MRSA osteomyelitis.
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