Chlorhexidine is not an essential component in alcohol-based surgical hand preparation: a comparative study of two handrubs based on a modified EN 12791 test protocol

Background: Surgical hand preparation is an essential part of modern surgery. Both alcohol-based and antiseptic detergent-based hand preparation are recommended practices, with a trend towards use of alcohol based handrubs. However, discussion has arisen whether chlorhexidine is a required ingredient in highly efficacious alcohol-based formulations, in view of providing sustained antimicrobial efficacy. Methods: One alcohol-only formulation (product A), containing ethanol and n-propanol, and one formulation containing a chlorhexidine-ethanol combination (product B) were directly compared with each other using a modified test protocol based on European standard EN 12791 (2016) with 25 volunteers. The alcohol-only formulation (product A) was applied for only 90 s, the chlorhexidine-alcohol formulation (product B) for 180 s. Microbial log reduction factors were determined and statistically compared immediately after application and at 6 h under surgical gloves. Results: The alcohol-only formulation (product A) achieved mean log reduction factors of 1.96 +/- 1.06 immediately after application and 1.67 +/- 0.71 after 6 h. The chlorhexidine-alcohol combination (product B) achieved mean log reduction factors of 1.42 +/- 0.79 and 1.24 +/- 0.90 immediately and after 6 h, respectively. The values for product A were significantly greater than those for product B at both measured time points (p = 0.025 immediately after application and p = 0.01 after 6 h). Conclusions: An optimized alcohol-only formulation tested according to a modified EN 12791 protocol in 25 healthy volunteers outperformed a chlorhexidine-alcohol formulation both immediately after application and at 6 h under surgical gloves, despite a much shorter application time. Thus, optimized alcohol-only formulations do not require chlorhexidine to achieve potent immediate and sustained efficacy. In conclusion, chlorhexidine is not an essential component for alcohol-based surgical hand preparation.