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This paper describes investigations on disinfection of germ carriers, contaminated with an alcoholic suspension of Bacillus cereus or Bacillus subtilis. Result of disinfection is compared with that of an additional heat treatment (80 degrees C, 60 min) after disinfection. Besides Formalin, Tegodor forte (Th. Goldschmidt, Essen) and P 3 oxonia active (Henkel KG, Düsseldorf) are tested with different concentration and duration. Heat activation was possible with all three disinfectants. For illuminating the conditions of activation, circumstances of heat action after disinfection with formaldehyde-aerosol have been varied. Heat activation in dry air, moist air and distilled water was not successful. Only in Nutrient Broth (Standard I-Bouillon; Merck, Darmstadt) spores were viable again, after activation. Addition of serum as a protective cover had no influence on the result. Consequences of the results on a disinfection method with formaldehyde-aerosol are discussed.

This paper deals with special conditions for testing the sporocidal effect of disinfectants. A method for the production of spore suspensions (Fig. 1) and the negative influence of heating to its resistance against disinfectants was described (Fig. 2). It was shown that spores of a non-virulent strain of Bac. anthracis could be used for this procedure (Fig. 3). In performing the suspension--and the germ-carrier test it was necessary to watch the effect of postinhibition and of inactivators. The application of 10 microliter disposible loops in the suspension-test was recommended. Since the test for the evaluation of the influence of organic matter on the results of disinfection was unreliable (Fig. 4), it was proposed to replace it by invention of a safety-factor. The germ-carrier test should be done with constant amounts of spores, dried to the surface under defined conditions. Exposition of germ-carriers to disinfectants should be done in a chamber with constant temperature and rel. humidity, since the results are strongly influenced by these factors (Fig. 5).