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Table 1 Mean reduction ± SD of Escherichia coli from artificially contaminated hands of 15 volunteers by reference treatment (2 × 3 ml of 60% iso-propanol for 60 s) or treatment with product A or product B (each 3 ml for 30 s); experiments differed only by the presence of valid neutralizers in the sampling fluid.

From: Insufficient neutralization in testing a chlorhexidine-containing ethanol-based hand rub can result in a false positive efficacy assessment

Preparation Active agent(s) and concentration(s) No neutralizers in sampling fluid P-value (vs. reference)* Neutralizers in sampling fluid P-value (vs. reference)*
   Samples without detectable test bacteria Mean log10-reduction ± SD   Samples without detectable test bacteria Mean log10-reduction ± SD  
Product A Ethanol (61%, w/w) chlorhexidine gluconate (1%, w/w) 9 / 15 4.8 ± 1.5 0.02 0 / 15 2.7 ± 0.4 0.033
Reference alcohol Iso-propanol (60%, v/v) 0 / 15 3.7 ± 0.8 n.a. 0 / 15 3.5 ± 0.9 n.a.
Product B Ethanol (85%, w/w) 0 / 15 3.3 ± 0.7 0.44 0 / 15 3.3 ± 0.7 0.11