Introduction / objectives
Critical questions have been raised in the scientific literature and by hand-hygiene thought leaders regarding the minimum alcohol concentration that assures efficacy of alcohol-based hand rubs (ABHR). The objective of this study was to determine the relative influences of alcohol concentration and product formulation on the efficacy of ABHR using internationally recognized methods.
Eleven commercially available alcohol-based hand rubs (gels and foams) containing between 60-90% (v/v) ethanol and WHO-recommended hand rub formulations containing 75% isopropanol or 80% ethanol were evaluated in a series of studies. Test methods included EN 1500 (Hygienic Hand Rub) and ASTM E1174 (Healthcare Personnel Handwash).
Four ABHR ranging from 70-80% ethanol met EN 1500 requirements with a 3 ml application volume applied for 30 seconds. Nine ABHR and the 2 WHO formulations were evaluated per E1174 at 2-ml application volumes. Of the products tested, only 2 products, a well-formulated 70% ethanol ABHR gel and well-formulated 70% ethanol foam, met the U.S. FDA requirements (reductions of ≥2 log10 after 1 application and ≥3 log10 after 10 applications). None of the other nine products achieved a 3-log10 reduction following the tenth application.
Product formulation was found to have a greater influence on efficacy than alcohol concentration. Well-formulated products containing 70% ethanol, including ABHR foams, can exhibit greater efficacy than products with higher alcohol levels. These results demonstrate that alcohol concentrations in excess of 70% are neither necessary, nor always sufficient to meeting global efficacy standards.
Disclosure of interest
S. Edmonds Employee of GOJO Industries, D. Macinga Employee of GOJO Industries, P. Mays-Suko: None declared, C. Duley: None declared, J. Arbogast Employee of GOJO Industries.