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Updated: Mar 8, 2026
In Vivo Mouse Model of Spinal Implant Infection
Published on: June 23, 2020
Intra-Articular Vancomycin Powder Eliminates Methicillin-Resistant S. aureus in a Rat Model of a Contaminated
Adam I Edelstein1, Joseph A Weiner, Ralph W Cook
11Department of Orthopaedic Surgery, Northwestern University, Chicago, Illinois.
Background:
Periprosthetic joint infection following hip and knee arthroplasty leads to poor outcomes and exorbitant costs. Topical vancomycin powder has been shown to decrease infection in many procedures such as spine surgery. The role of vancomycin powder in the setting of total joint arthroplasty remains undefined. Our aim was to evaluate the efficacy of intra-articular vancomycin powder in preventing infection in a rat model of a contaminated intra-articular implant.
Methods:
Thirty-two female Sprague-Dawley rats underwent knee arthrotomy and implantation of a femoral intramedullary wire with 1 mm of intra-articular communication. The knee joint was also inoculated with 1.5 × 10 colony forming units (CFU)/mL of methicillin-resistant Staphylococcus aureus (MRSA). Four treatment groups were studied: (1) no antibiotics (control), (2) preoperative systemic vancomycin, (3) intra-articular vancomycin powder, and (4) both systemic vancomycin and intra-articular vancomycin powder. The animals were killed on postoperative day 6, and distal femoral bone, joint capsule, and the implanted wire were harvested for bacteriologic analysis. Statistical analyses were performed using Wilcoxon rank sum and Fisher exact tests.
Results:
There were no postoperative deaths, wound complications, signs of vancomycin-related toxicity, or signs of systemic illness in any of the treatment groups. There were significantly fewer positive cultures in the group that received vancomycin powder in combination with systemic vancomycin compared with the group that received systemic vancomycin alone (bone: 0% versus 75% of 8, p = 0.007; Kirschner wire: 0% versus 63% of 8, p = 0.026; whole animal: 0% versus 88% of 8, p = 0.01). Only animals that received both vancomycin powder and systemic vancomycin showed evidence of complete elimination of bacterial contamination.
Conclusions:
In a rat model of a contaminated intra-articular implant, use of intra-articular vancomycin powder in combination with systemic vancomycin completely eliminated MRSA bacterial contamination. Animals treated with systemic vancomycin alone had persistent MRSA contamination.
Clinical Relevance:
This animal study presents data suggesting that the use of intra-articular vancomycin powder for reducing the risk of periprosthetic joint infections should be investigated further in clinical studies.
Insights
Intra-articular vancomycin powder combined with systemic vancomycin completely eliminated MRSA contamination in a rat joint infection model. This combination therapy shows promise for preventing periprosthetic joint infections.
Area of Science:
- Orthopedic Surgery
- Infectious Disease
- Pharmacology
Background:
- Periprosthetic joint infections (PJIs) following hip and knee arthroplasty result in poor patient outcomes and significant healthcare costs.
- Topical vancomycin powder is effective in reducing infections in various surgical procedures, but its role in total joint arthroplasty is not well-defined.
- This study investigates the efficacy of intra-articular vancomycin powder in preventing PJIs in a rodent model.
Purpose of the Study:
- To evaluate the effectiveness of intra-articular vancomycin powder in preventing methicillin-resistant Staphylococcus aureus (MRSA) contamination in a rat model of infected knee arthroplasty.
- To compare the efficacy of intra-articular vancomycin powder alone, systemic vancomycin alone, and a combination of both in preventing bacterial contamination.
Main Methods:
- A rat model of knee arthroplasty with MRSA inoculation was used, involving 32 female Sprague-Dawley rats.
- Four treatment groups were established: control (no antibiotics), systemic vancomycin, intra-articular vancomycin powder, and combined systemic and intra-articular vancomycin.
- Bacteriologic analysis of bone, joint capsule, and implants was performed on postoperative day 6.
Main Results:
- No treatment-related deaths, toxicity, or systemic illness were observed.
- The combination of intra-articular vancomycin powder and systemic vancomycin resulted in significantly fewer positive cultures compared to systemic vancomycin alone.
- Complete elimination of MRSA contamination was achieved only in the group receiving both intra-articular vancomycin powder and systemic vancomycin.
Conclusions:
- Intra-articular vancomycin powder, when used in conjunction with systemic vancomycin, completely eradicated MRSA contamination in a rat model of infected knee arthroplasty.
- Systemic vancomycin alone was insufficient to clear persistent MRSA contamination.
- These findings suggest that intra-articular vancomycin powder warrants further investigation in clinical trials for preventing PJIs.
