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American Association for Hand Surgery

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Synergistic Effect of Silver Carboxylate and Chlorhexidine Gluconate Coated Sutures decreases Surgical Site Infections and Wounds of the Hand and Wrist by Methicillin-resistant Staphylococcus aureus and Cutibacterium acnes
Neel Vishwanath, BS1, Dioscaris Garcia, PhD1, Sai Allu, BS1, Carole Spake, MSc1, Dominique Dockery, BA1, Ellis Berns, BS1, Edward Akelman, MD2 and Christopher Born, MD1, (1)Warren Alpert Medical School of Brown University, Providence, RI, (2)Department of Orthopaedic Surgery, Warren Alpert Medical School of Brown University, Providence, RI

Surgical site infection (SSI) following hand and wrist surgery is a significant complication with a reported incidence of 0.33%-10%. [1] [2] Infections lead to increased hospitalization times, revision procedures, and financial burden. [3] Despite current preoperative antiseptic practices, methicillin-resistant Staphylococcus aureus (MRSA) and Cutibacterium acnes (C. acnes) are known to colonize wound sites in the hand and wrist, promoting infection and wound dehiscence. [4] [5] [6] While chlorhexidine (CHG) has broad spectrum activity, it fails to penetrate into the pilosebaceous glands where C. acnes resides. [7] [8] Previous studies have indicated that a silver carboxylate titanium-dioxide polydimethylsiloxane antimicrobial matrix can penetrate into these glands. [9] We hypothesize that when the penetrative nature of silver carboxylate is combined with the high bactericidal broad-spectrum activity of CHG, it will be efficacious against both nosocomial pathogens.
Dose response curves (DRC) and drop assays were generated to determine (1) therapeutic concentrations for C. acnes and MRSA and (2) optimal therapeutic ratio of silver carboxylate to CHG. Coatings were then applied to Arthrex FiberWire® sutures and Ethicon Coated VICRYL® sutures. Kirby Bauer assays were conducted to visualize and quantify the antimicrobial efficacy of the chemistry. Ethicon PDS® Plus antibacterial sutures served as antimicrobial controls. Graphite furnace atomic absorption spectroscopy (GFAAS) was used to measure silver elution from sutures over time.
DRC results indicated that therapeutic concentration of silver carboxylate for MRSA was 120x-150x dopage. Drop assay performed in conjunction with DRC determined 30x-60x dopage was therapeutic against C. acnes. Therapeutic ratio of silver carboxylate to CHG was 1:1. ANOVA testing of the Kirby Bauer assay demonstrated that 60x silver-carboxylate:CHG coated FiberWire® and Ethicon® both showed unchanged bactericidal activity over time against C. acnes (p = 0.147, p = 0.998, respectively), and the 150x silver-carboxylate:CHG coated FiberWire® and Ethicon® sutures demonstrated sustained bactericidal activity against MRSA (p= 0.53, p = 0.803, respectively). Across suture types and between pathogens, the coating maintained its efficacy significantly better than Ethicon PDS® Plus antibacterial sutures over the 3-4 day period (p <0.01). GFAAS testing demonstrated that silver-carboxylate:CHG maintained elution over 96 hours in a majority of conditions. At the identified dopages, the concentration of silver was never higher than 0.3 mg, much lower than the safe daily limit of 5 mg/kg/day. [9] Overall, the silver-carboxylate:CHG chemistry demonstrated safe dosing, antimicrobial efficacy, and extended elution properties. Use of this synergistic combination could prevent hand and wrist SSI by MRSA and C.acnes.


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