5.1 Hand hygiene is considered one of the most important measures for preventing the spread of infectious microorganisms. Hand rubs reduce the microbial load on the hands without the use of soap and water, and are thus an important tool in the practice of good hand hygiene. Alcohol-based hand rubs are recommended in healthcare settings for use on hands that are not visibly soiled. They are formulated to be applied full strength to dry hands, "rubbed in" until dry, and are not rinsed off.

5.2 This test method is designed specifically to evaluate hand rubs for efficacy in eliminating bacteria from experimentally-contaminated hands. It is designed as an alternative to Test Method E1174, which was intended primarily to evaluate antimicrobial handwashing agents that are lathered with the aid of water and then rinsed off. When using Test Method E1174 to evaluate hand rubs, inadequate drying of the hands after contamination dilutes the test material and can compromise activity, to result in an underestimation of effectiveness. Additionally, because hand rubs are not rinsed after product use, activity can be further degraded by build-up of soil from the contaminating broth and inactivated challenge bacteria on the hands.

5.2.1 In this method, application to the hands of a small volume of high-titer test bacteria suspension minimizes soil load such that the skin is completely dry prior to application of the test material. Further, by applying the bacterial suspension only prior to those test material application cycles followed by sampling, excessive buildup of killed bacteria on the hands is avoided, and the potential impact of non-volatile test product ingredients on bacteria-eliminating effectiveness after ten consecutive applications can be specifically assessed.

5.3 A reference control is evaluated for each subject prior to evaluation of the test material. Data from the reference control helps to control for inter-subject variability, inter-experimental variability, and inter-laboratory variability; and enables improved statistical comparison of test materials evaluated in the same experiment.

5.4 This test method can be used to test any form of hand rubs, including gels, rinses, sprays, foams, and wipes when used according to label directions at typical "in-use" doses.

5.5 Susceptibility to biocides can vary among different species of bacteria and major differences have been noted between gram-negative and gram-positive organisms. This test method provides the option to use either a gram-negative bacterium (Serratia marcescens) or a gram-positive bacterium (Staphylococcus aureus) as the test organism. S. marcescens is used as a test organism in both Test Method E1174 and Test Method E2276. S. aureus is a highly relevant pathogen in healthcare, institutional, and community settings. Moreover, hands are an important vehicle in the transfer of S. aureus between people and the environment, and in the transfer between individuals.

5.6 This test method may be used as an alternative to Test Method E2276, which limits the test bacteria to the fingerpads and does not incorporate actual use conditions such as friction during hand rubbing.

5.7 The investigator should be aware of potential health risks associated with the use of these organisms and precautions similar to those referenced in Section 8 should be taken.