Abstract
ABSTRACTWe are developing electrical approaches to treat biofilm‐associated orthopedic foreign‐body infection. Although we have previously shown that such approaches have antibiofilm activity, the effects on bone have not been assessed. Herein, low‐amperage 200 μA fixed direct current (DC) was compared with no current, in a rat femoral foreign‐body infection model. In the infected group, a platinum implant seeded with S. epidermidis biofilm (105 CFU/cm2), plus 50 μL of a 109 CFU suspension of bacteria, were placed in the femoral medullary cavity of 71 rats. One week later, rats were assigned to one of four groups: infected with no current or DC, or uninfected with no current or DC. After 2 weeks, bones were removed and subjected to histopathology, micro‐computed tomography (μCT), and strength testing. Histopathology showed no inflammation or bony changes/remodeling in the uninfected no current group, and some osteoid formation in the DC group; bones from the infected no current group had evidence of inflammation without bony changes/remodeling; along with inflammation, there was moderate osteoid present in the DC group. μCT showed more cortical bone volume and density, trabecular thickness, and cancellous bone volume in the DC group compared with the no current group, for both uninfected and infected bones (p < 0.05). There was no difference in torsional strength or stiffness between the no current versus DC groups, for both infected and uninfected bones (p > 0.05). © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
Highlights
Joint replacement surgery is increasingly common in the United States.[1]
Because organisms associated with prosthetic joint infection (PJI) are typically found in biofilms, PJI is difficult to treat with antibiotics alone.[1,5,6] We have previously described the use of low-amperage fixed direct current (DC) as an antibiofilm strategy in in vitro and in vivo rabbit and rat foreign-body osteomyelitis models, showing that amperages as low as 2 mA in vitro and 200 mA in vivo reduced bacterial loads compared with untreated controls.[7,8,9,10] In addition, other investigators have shown that S. epidermidis biofilms can be made to detach from surgical stainless steel by the use of DC of 100 mA.[11,12] Up until now, few studies on the effects of DC on bone formation/resorption and strength have been performed
A modified foreign-body osteomyelitis model was established in male Wistar rats (Envigo, Huntingdon, Cambridgeshire, UK), weighing 300 g, as done previously,(8) in which 50 mL of a 109 CFU suspension of S. epidermidis was injected into the medullary cavity of the left femur, followed by implantation of a 10- Â 3-mm platinum wire preseeded with S. epidermidis biofilm by incubation in trypticase soy broth (TSB) with CFU/mL S. epidermidis for 2 hours
Summary
Joint replacement surgery is increasingly common in the United States.[1]. with the increase in arthroplasties comes an increased chance of prosthetic joint infection (PJI). Because organisms associated with PJI are typically found in biofilms, PJI is difficult to treat with antibiotics alone.[1,5,6] We have previously described the use of low-amperage fixed direct current (DC) as an antibiofilm strategy in in vitro and in vivo rabbit and rat foreign-body osteomyelitis models, showing that amperages as low as 2 mA in vitro and 200 mA in vivo reduced bacterial loads compared with untreated controls.[7,8,9,10] In addition, other investigators have shown that S. epidermidis biofilms can be made to detach from surgical stainless steel by the use of DC of 100 mA.[11,12] Up until now, few studies on the effects of DC on bone formation/resorption and strength have been performed. Pathology was employed to assess adverse effects at the tissue level, as well as bone formation and resorption, using bones that were uninfected or infected with S. epidermidis that had received 200 mA DC or no current
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