Evaluation of an alcohol-based surgical hand disinfectant containing a synergistic combination of farnesol and benzethonium chloride for immediate and persistent activity against resident hand flora of volunteers and with a novel in vitro pig skin model.

Abstract

Objective: To evaluate the immediate, persistent and sustained in vivo activity of an alcohol-based surgical hand disinfectant, consisting of a zinc gel and a preservative system containing a synergistic combination of farnesol and benzethonium chloride (ZBF disinfectant), and to develop a pig skin model for in vitro evaluation of the immediate and persistent efficacy of alcohol-based surgical hand disinfectants against resident hand flora.

Design: The in vivo immediate, persistent, and sustained activity of ZBF disinfectant was evaluated using human volunteers and the "glove-juice" method described in the US Food and Drug Administration's Tentative Final Monograph (FDA-TFM) for Healthcare Antiseptic Products. A novel in vitro pig skin model was developed to compare the immediate and persistent activity of alcohol-based surgical hand disinfectants against resident flora using Staphylococcus epidermidis as the test organism. Four alcohol-based surgical hand disinfectants were evaluated using this model.

Results: The results for the ZBF disinfectant exceed the FDA-TFM criteria for immediate, persistent, and sustained activity required for surgical hand disinfectants. The reduction factors for the 4 hand disinfectants obtained using the pig skin model show good agreement with the log(10) reductions in concentrations of hand flora obtained using human volunteers to test for immediate and persistent activity.

Conclusion: The ZBF disinfectant we evaluated met the FDA-TFM criteria for surgical hand disinfectants. The immediate and persistent efficacy of the surgical hand disinfectants evaluated with the novel pig skin model described in this study shows good agreement with the results obtained in vivo.