Does a preceding hand wash and drying time after surgical hand disinfection influence the efficacy of a propanol-based hand rub?

BACKGROUND: Recently, a propanol-based hand rub has been described to exceed the efficacy requirements of the European standard EN 12791 in only 1.5 min significantly. But the effect of a 1 min preceding hand wash and the effect of one additional minute for evaporation of the alcohol after its application on the efficacy after a 1.5 min application time has never been studied. METHODS: We have investigated a propanol-based hand rub (Sterillium(®), based on 45% propan-2-ol, 30% propan-1-ol and 0.2% mecetronium etilsulfate) in three variations: with (A) and without (B) a 1 min hand wash before the disinfection of 1.5 min with immediate sampling after the disinfection; and (C) without a hand wash before the disinfection but with sampling 1 min after the disinfection. The efficacy of the three variations was compared to the reference treatment of EN 12791. All experiments were performed in a Latin-square design with 20 volunteers. Pre- and post-values (immediate and after 3 hr) were obtained according to EN 12791. RESULTS: The 3 min reference disinfection reduced resident hand bacteria on average by 1.8 log(10 )steps (immediate effect) and 1.4 log(10)-steps (sustained effect) respectively. Method A was equally effective as the reference (immediate efficacy: 1.5 log(10)-steps; sustained efficacy: 1.6 log(10)-steps). Method B seemed to be more effective (immediate efficacy: 2.3 log(10)-steps; sustained efficacy: 1.7 log(10)-steps). Method C revealed the best efficacy (immediate efficacy: 2.3 log(10)-steps; sustained efficacy: 2.0 log(10)-steps). A comparison of all three treatment variations and the reference treatment revealed a significant difference for the immediate efficacy (p = 0.026; Friedman test), but not for the sustained efficacy (p = 0.430). A post-hoc-test for the immediate efficacy indicated a significant difference between methods A and C (p < 0.05; Wilcoxon-Wilcox test). Hence, none of the treatment variations was significantly less effective than the reference treatment. CONCLUSION: An application of the propanol-based hand rub for 1.5 min after 1 min hand wash fulfills the efficacy requirements of EN 12791. The efficacy can be improved to some extent by omitting the preceding hand wash and by awaiting the evaporation of the alcohol which is clinical practice anyway. The preceding hand wash has the most negative effect on the immediate effect. Based on our data hands should not be routinely washed before the disinfection period unless there is a good reason for it such as visible soiling.