Progress not panacea: vancomycin powder efficacy and dose evaluated in an in vivo mouse model of spine implant infection

Abstract

BACKGROUND-Intrawound vancomycin powder (VP) has been rapidly adopted in spine surgery with apparent benefit demonstrated in limited, retrospective studies. Randomized trials, basic science, and dose response studies are scarce. PURPOSE-This study aims to test the efficacy and dose effect of VP over an extended time course within a randomized, controlled in vivo animal experiment. STUDY DESIGN/SETTING-Randomized controlled experiment utilizing a mouse model of spine implant infection with treatment groups receiving vancomycin powder following bacterial inoculation. METHODS-Utilizing a mouse model of spine implant infection with bioluminescent Staphylococcus aureus, 24 mice were randomized into 3 groups: 10 infected mice with VP treatment (+VP), 10 infected mice without VP treatment (No-VP), and 4 sterile controls (SC). Four milligrams of VP (mouse equivalent of 1 g in a human) were administered before wound closure. Bioluminescence imaging was performed over 5 weeks to quantify bacterial burden. Electron microscopy (EM), bacterial colonization assays (Live/Dead) staining, and colony forming units (CFU) analyses were completed. A second dosing experiment was completed with 34 mice randomized into 4 groups: control, 2 mg, 4 mg, and 8 mg groups. RESULTS-The (+VP) treatment group exhibited significantly lower bacterial loads compared to the control (No-VP) group, (p<.001). CFU analysis at the conclusion of the experiment revealed 20% of mice in the +VP group and 67% of mice in the No-VP group had persistent infections, and the (+VP) treatment group had significantly less mean number of CFUs (p<.03). EM and Live/ Dead staining revealed florid biofilm formation in the No-VP group. Bioluminescence was suppressed in all VP doses tested compared with sterile controls (p<.001). CFU analysis revealed a

Point-of-care antimicrobial coating protects orthopaedic implants from bacterial challenge

“…To demonstrate the versatility of our coating technology, we explored the possibility of transferring the coating process to a spine implant infection model 35 . Besides PJI, spine implant infection is another devastating complication that occurs in 2–8% of all elective spine surgeries.…”

“…This is often the case for spine surgeries. We recently assessed and published on the use of vancomycin powder to prevent infection 35 . In these studies, we find that vancomcyin powder completely suppresses bioluminescence signal; however, 20% of the animals have persistent infections despite the large amounts of vancomycin powder used of 2, 4, and 8 mg per wound.…”

“…The following is a summary from the previously published description of the in vivo mouse model of spine implant infection 35 . All procedures were approved by the UCLA Animal Research Committee (ARC #2008-112-41 C).…”

Animal Models for Postoperative Implant‐Related Spinal Infection

“…It is a powerful tool to study spinal implant infections further. Park et al 63 used this model to test the efficacy and dose effect of vancomycin powder over an extended time course. This model was also used to evaluate the efficacy of combined antibiotic therapy (vancomycin and rifampin) on postoperative spinal infections 64 .…”

“…It is a powerful tool to study spinal implant infections further. Park et al 63 . used this model to test the efficacy and dose effect of vancomycin powder over an extended time course.…”