Hygienic hand disinfection

The purpose of hygienic hand disinfection is to render hands safe after contact with pathogens. Comparing effects of disinfection procedures on infection ratios is too difficult for routine purposes but the degerming efficacy may be determined in laboratory tests with volunteers. In the Vienna test model the efficacy of a specific procedure being tested is compared to that of a standard disinfection (rubbing into hands 3 ml of isopropanol 60% v/v, 30 seconds, twice) tested in parallel with the same volunteers. This ensures standardization, thus comparability of results between laboratories, and provides the investigator with a yardstick for efficacy. The model includes artificial contamination, assessment of the release of test bacteria (E. Coli ATCC 11229) before and after disinfection by the finger tip method, and addition of neutralizers to sampling fluids. Alcohols in appropriate concentrations are highly effective (log reductions: greater than 4.0) whereas procedures employing disinfectant detergents act like soap (log reductions: less than or equal to 3.2) and may cause dissemination of pathogens.