Stefanie M Shiels1, David J Tennent2, Kevin S Akers3, Joseph C Wenke4. 1. Extremity Trauma and Regenerative Medicine Task Area, US Army Institute of Surgical Research, JBSA-Fort Sam Houston, TX, United States. Electronic address: stefanie.m.shiels.ctr@mail.mil. 2. Extremity Trauma and Regenerative Medicine Task Area, US Army Institute of Surgical Research, JBSA-Fort Sam Houston, TX, United States; Department of Orthopaedics, San Antonio Military Medical Center (Brooke Army Medical Center), JBSA-Fort Sam Houston, TX, United States. 3. US Army Institute of Surgical Research, JBSA-Fort Sam Houston, TX, United States; Infectious Disease Service, San Antonio Military Medical Center (Brooke Army Medical Center), JBSA-Fort Sam Houston, TX, United States. 4. Extremity Trauma and Regenerative Medicine Task Area, US Army Institute of Surgical Research, JBSA-Fort Sam Houston, TX, United States.
Abstract
BACKGROUND: Open fractures are often complicated by infection. In cases of severe soft tissue and vascular injury, systemic antibiotics may be ineffective due to their inability to reach and provide direct antimicrobial activity to the zone of injury. High antibiotic concentrations within the wound can be achieved with reduced systemic toxicity by using local antibiotic delivery. As bacteria associated with musculoskeletal injuries frequently form biofilms, antibiotic selection is important. Herein, the use of rifampin, an antibiotic with activity against biofilms, delivered via polymethylmethacrylate (PMMA) beads is evaluated for use in a traumatic musculoskeletal wound model. METHODS: PMMA beads loaded with rifampin, or combinations of rifampin and vancomycin, were prepared and evaluated for time to curing, drug release kinetics in vitro, and infection prevention in vivo using a well-established rat model of musculoskeletal infection. A segmental bone defect was created and contaminated with methicillin susceptible Staphylococcus aureus (UAMS-1). Wounds were debrided, irrigated, and treated with PMMA beads, containing rifampin or combinations of rifampin plus vancomycin, following a 6-h (early) or 24-h (delayed) treatment. After 14days, tissue, implants, and beads were removed for bacterial quantification and assessed for rifampin resistance. RESULTS: There was a direct association between loaded concentration and release kinetics of the rifampin and vancomycin from PMMA beads. Higher rifampin concentrations delayed PMMA curing times. The addition of vancomycin to PMMA resulted in more rapid release of rifampin from beads. However, the highest concentration of rifampin loaded PMMA beads (10% wt/wt) was the only treatment to significantly reduce bacterial counts. No rifampin resistance was observed. CONCLUSION: Although higher concentrations of rifampin resulted in significant reductions of bacteria, these levels extended PMMA curing times and transformed PMMA material characteristics. While these characteristics make the material unsuitable for weight-bearing applications, such as total joint arthroplasty, the use of rifampin-loaded PMMA beads may be an effective intervention in a contaminated traumatic extremity wound due to its ability to eradicate biofilms.
BACKGROUND: Open fractures are often complicated by infection. In cases of severe soft tissue and vascular injury, systemic antibiotics may be ineffective due to their inability to reach and provide direct antimicrobial activity to the zone of injury. High antibiotic concentrations within the wound can be achieved with reduced systemic toxicity by using local antibiotic delivery. As bacteria associated with musculoskeletal injuries frequently form biofilms, antibiotic selection is important. Herein, the use of rifampin, an antibiotic with activity against biofilms, delivered via polymethylmethacrylate (PMMA) beads is evaluated for use in a traumatic musculoskeletal wound model. METHODS:PMMA beads loaded with rifampin, or combinations of rifampin and vancomycin, were prepared and evaluated for time to curing, drug release kinetics in vitro, and infection prevention in vivo using a well-established rat model of musculoskeletal infection. A segmental bone defect was created and contaminated with methicillin susceptible Staphylococcus aureus (UAMS-1). Wounds were debrided, irrigated, and treated with PMMA beads, containing rifampin or combinations of rifampin plus vancomycin, following a 6-h (early) or 24-h (delayed) treatment. After 14days, tissue, implants, and beads were removed for bacterial quantification and assessed for rifampin resistance. RESULTS: There was a direct association between loaded concentration and release kinetics of the rifampin and vancomycin from PMMA beads. Higher rifampin concentrations delayed PMMA curing times. The addition of vancomycin to PMMA resulted in more rapid release of rifampin from beads. However, the highest concentration of rifampin loaded PMMA beads (10% wt/wt) was the only treatment to significantly reduce bacterial counts. No rifampin resistance was observed. CONCLUSION: Although higher concentrations of rifampin resulted in significant reductions of bacteria, these levels extended PMMA curing times and transformed PMMA material characteristics. While these characteristics make the material unsuitable for weight-bearing applications, such as total joint arthroplasty, the use of rifampin-loaded PMMA beads may be an effective intervention in a contaminated traumatic extremity wound due to its ability to eradicate biofilms.
Authors: Elysia A Masters; Ryan P Trombetta; Karen L de Mesy Bentley; Brendan F Boyce; Ann Lindley Gill; Steven R Gill; Kohei Nishitani; Masahiro Ishikawa; Yugo Morita; Hiromu Ito; Sheila N Bello-Irizarry; Mark Ninomiya; James D Brodell; Charles C Lee; Stephanie P Hao; Irvin Oh; Chao Xie; Hani A Awad; John L Daiss; John R Owen; Stephen L Kates; Edward M Schwarz; Gowrishankar Muthukrishnan Journal: Bone Res Date: 2019-07-15 Impact factor: 13.567