[Evaluation of procedures for hygienic disinfection of hands: comparison of two methods, for artificially contaminating hands and use of an automatic colony-counter (author's transl)].

Testing procedures for the Hygienic Disinfection of hands, two kinds of artificial contamination have been compared: Application of one drop of bacterial suspension onto each fingertip as described in the DGHM-"Richtlinien" and immersion of hands as described in our previous papers. When using our method, fingertips released higher numbers of testbacteria. Since pre- as well as post-values were elevated, disinfection-tests applying one of each contamination method resulted in log10 reductions which did not differ significantly. Using an automated scanning colony counter we were able to save 2/3 of time otherwise required for manual counts. Up to 10(2) colonies per plate manual counts were practically identical with the counters results, whereas with higher colony-numbers the counter showed an increasing tendency to under-estimate the numbers of colonies. Since colonies of skin-staphylococci are not recognised by the automated counter, we cultured our rinsing-fluids on nutrient agar containing 0.05% of sodium-desoxycholate in order to inhibit the autochthonous skin flora. This supplement influenced the colony counts of our test-bacterium to a very minor degree only, the reduction factors were not at all altered.