A novel method has been developed for the evaluation of alcohol-based hand rubs (ABHR) that employs a hand contamination procedure that more closely simulates the in-use conditions of ABHR. Hands of human subjects were contaminated with 0.2 ml of a concentrated suspension of Serratia marcescens (ATCC 14756) to achieve baseline contamination between 8 and 9 log 10 CFU/hand while allowing product to be applied to dry hands with minimal soil load. Evaluation of 1.5 ml of an ABHR gel containing 62% ethanol produced log 10 reductions of 2.66 ؎ 0.96, 2.40 ؎ 0.50, 2.41 ؎ 0.61, and 2.33 ؎ 0.49 (means ؎ standard deviations) after 1, 3, 7, and 10 successive contamination/product application cycles. In a study comparing this low-volume contamination (LVC) method to ASTM E1174, product dry times were more realistic and log 10 reductions achieved by the ABHR were significantly greater when LVC was employed (P < 0.05). These results indicate that a novel low-volume hand contamination procedure, which more closely represents ABHR use conditions, provides more realistic estimates of in-use ABHR efficacies. Based on the LVC method, log 10 reductions produced by ABHR were strongly dependent on the test product application volume (P < 0.0001) but were not influenced by the alcohol concentration when it was within the range of 62 to 85% (P ؍ 0.378).Alcohol-based hand rubs (ABHR) are recommended as the primary means for hand hygiene in health care settings when hands are not visibly soiled (5, 21). They are also used as an adjunct to hand washing in food preparation settings (1). Because ABHR use is prescribed for situations when hands are dry and not soiled (5, 21), and in order to produce data that reflect reality, it is vital that excessive hand wetness and soiling are avoided during the in vivo testing of ABHR.However, high soil and/or hand wetness are predominant features of in vivo methods for evaluating the efficacy of ABHR products (2,6,10,19,20). Several authors have noted the shortcomings of the current test methods and have called for development of in vivo protocols that more closely simulate real world conditions of use (18,20,21). Previous studies from our labs investigating the appropriateness of method ASTM E1174 for evaluating ABHR demonstrated that when hands are contaminated with 4.5 ml of a liquid bacterial culture, organic nutrients from the growth medium and hand wetness at the time of test product application, resulting from insufficient drying time, compromised the antibacterial activities of ABHR (15). Furthermore, hand wetness is exacerbated with repeated hand contamination, which dilutes the active ingredient and leads to a decline in efficacy over multiple hand contamination/product application cycles. Our studies have indicated that modification of the ASTM E1174 hand contamination procedure to decrease either the contaminant volume or reduce the soil load produces only modest changes to these efficacy trends. However, when both the soil load and hand wetness were significantly reduced simultaneously b...
