5.1 This in vivo procedure is designed to test the ability of hygienic handwash or handrub agents to eliminate selected types of bacteria from experimentally contaminated skin of the hands of adult subjects. Since the two thumbpads and all eight fingerpads can be used in any given test, it allows for the incorporation of an input control (two), control for viable bacteria remaining after the inoculum has been allowed to dry (two), bacteria eliminated after treatment with a control or reference solution (two), and up to four replicates to assess the bacteria-eliminating efficiency of the product under test. No more than 100 µL of the test bacterial suspension is required to complete one test. The results of testing with this test method may form the basis for confirmatory tests using a suitable whole-hand test protocol, such as Test Method E1174.

5.2 Whereas this test method relates to testing with bacteria, it can be readily adapted to work with protozoa and bacteriophages. Similar methods for work with fungi (Test Method E2613) and viruses of human origin (Test Method E1838) are already ASTM standards.

5.3 Potentially infectious microorganisms left on hands after washing can be reduced further by drying the washed hands with paper, cloth, or warm air (7). A step for the drying of fingerpads after exposure to the control or test solution, therefore, has not been included to avoid bacterial removal by the drying process itself.

5.4 This test method is not meant for use with surgical hand scrubs (Test Method E1115) or preoperative skin preps (Test Method E1173).

5.5 The level of contamination with viable bacteria on each fingerpad after the drying of the inoculum should be five- to ten-fold higher than the product performance criterion required. For example, the titer in the dried inoculum on each fingerpad should be about 10⁵ colony forming units of the test bacterium when a >10⁴ reduction is required under the conditions of this test method.