Povidone-iodine-alcohol is superior to chlorhexidine-alcohol in its antimicrobial efficacy on the anaerobic microbial flora in surgical skin preparation of the shoulder region

Abstract

Background: Cutibacterium acnes is part of the anaerobic skin microbiome and resides in deeper skin layers. The organism is an important agent of surgical site infections (SSI), particularly in shoulder surgery, and is difficult to target with skin antisepsis. We hypothesized that prolonged preparation with an agent that penetrates deeper into the skin is more effective in shoulder surgery. Thus, we compared two different classes of antiseptics, each combined with alcohol, and each applied with two different contact times. Methods: Shoulders of 16 healthy volunteers were treated for 2.5 min (standard) or 30 min (prolonged) with alcohol-based chlorhexidine (CHG-ALC; 2% w/v CHG, 55% w/v [70% v/v] 2-propanol) or alcohol-based povidone iodine (PVP-I-ALC; 3.24% w/v PVP-I, 38.9% w/v 2-propanol, 37.3% w/v ethanol). Skin sites were sampled before, immediately after, and 3 h after treatment. Results: Aerobic skin flora was reduced more effectively by PVP-I-ALC than by CHG-ALC after 2.5 min and immediate sampling, but not after prolonged contact times and 3-h sampling. Anaerobic flora was reduced more effectively by PVP-I-ALC than by CHG-ALC after standard and prolonged contact times and immediate sampling, but not after 3-h sampling. None of the volunteers reported negative effects from skin antisepsis. Conclusions: PVP-I-ALC is more efficacious than CHG-ALC for topical skin antisepsis regarding the anaerobic flora on the skin of the shoulder. Standard and prolonged contact times demonstrated superiority for PVP-I-ALC for samples taken immediately, but missed significance 3 h after application. The clinical relevance of these findings should be studied with SSI as an endpoint.