100 DISINFECTANTS 



onic detergents" contain them, often in form of sulfonic 

 acids, in the anion. 



Many of the wetting agents are not only detergents, 

 but good disinfectants. Baker, Harrison and Miller 

 (1941 and 1942) found that cationic detergents as a 

 group kill Gram-positive bacteria more readily than 

 Gram-negative species. Of the 9 detergents investi- 

 gated, all but one killed streptococci, lactobacilli and 

 staphylococci within 10 minutes when diluted 1:3000. 

 Two of the 9 failed to kill Bacterium coli and typhosum, 

 three failed with Proteus vulgaris. 



The anionic detergents were much less efficient. Eight 

 of them were tested with the bacteria mentioned above, in 

 1:1000 dilution. After a 10 minutes' exposure, only 

 three had killed the lactobacilli, two had killed the strep- 

 tococci, and none was powerful enough to kill the two 

 staphylococci; even with 90 minutes exposure, only one 

 of the eight detergents could destroy the staphylococci. 

 None of these compounds was effective against any of the 

 Gram-negative test organisms. 



A very remarkable phenomenon was observed by Mil- 

 ler, Abrams, Huber and Klein (1943) when cationic de- 

 tergents were used to disinfect hands. It seems that the 

 detergent deposits on the hands an invisible, non-percep- 

 tible film which retains the bacteria under it without 

 killing them, while the outer surface becomes sterile. 

 The film is not easily broken mechanically, c.g,, by scrub- 

 bing, and hands treated with cationic detergents can be 

 considered practically sterile for a considerable time. 

 Frequent dipping into saline solution Or long rinsing 

 with running water tends to deteriorate the film. Soap 

 breaks it up promptly, releasing the viable bacteria un- 

 derneath. The authors did not offer an explanation for 

 the different action of the two sides of the film. 



