Products and application
The following preparations were used: propan-1-ol (60%, v/v) as reference alcohol of EN 12791, and Sterillium based on 45% (w/w) propan-2-ol, 30% (w/w) propan-1-ol, and 0.2% (w/w) mecetronium etilsulfate (Bode Chemie GmbH & Co. KG, Hamburg, Germany). Sterillium was applied to the hands for 1.5 min as described recently . The reference alcohol was applied to the hands for 3 min according according to EN 12791 .
The volunteers washed their hands with a non-medicated soap (sapo kalinus) as described by EN 12791. Thereafter hands were rinsed with running tap water and dried with a sterile paper towel.
Determination of the pre-values and post-values
Sampling, cultivation and calculation of values were done according to EN 12791. Volunteers rubbed the phalanges of one hand (randomly selected) for one minute in TSB (pre-value) or TSB with addition of 3% Tween 80, 3% saponin, 0.1% histidine, and 0.1% cysteine as neutralizers (immediate effect after disinfection or drying), because these neutralizers are shown to be effective . The other hand was gloved for 3 hours for the assessment of the sustained effect. After taking off the glove sampling was done in the same way as for the immediate effect. For each volunteer the logarithmic reduction factor (RF) was obtained as the difference between the log10 pre-value and log10 post values.
Each of the 20 volunteers was treated with the reference product for 3 min as well as with Sterillium for 1.5 minutes. Between each product application, a rest period of at least one week elapsed in order to allow the reconstitution of normal skin flora.
We have investigated surgical hand disinfection with Sterillium 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. All three applications were tested in a Latin-square design against the reference treatment.
A product is considered effective for surgical disinfection if the mean of the RF of both the immediate and sustained effect is not significantly lower than the corresponding mean RF of the reference treatment . Differences in the immediate and sustained effects between the reference treatment and the three variations of product application were investigated by non-parametric Friedman tests, followed by the Wilcoxon-Wilcox procedure for pairwise comparisons. A p-value < 0.05 was chosen to indicate a significant difference.