Bacteriostasis with Mixed Dyes 



19 



6 (1966) 



Bacteriostasis with mixed dyes. 

 By JOHN W. CHURCHMAN 



[From the Department of Hygiene, Cornell University Medical 

 College, Neiv York City] 



Since the time of Ehrlich, chemotherapy has been largely con- 

 cerned with efforts to fortify the weaknesses of bactericidal and 

 paracitocidal substances by chemical manipulation of the mole- 

 cule. It has been recently found, however, that the end in view 

 may, in some cases, be easily achieved by the use of simple mix- 

 tures of certain dyes which have been previously shown to pos- 

 sess opposite selective bacterio-static properties. The fact was 

 reported to this society last year that acid fuchsin possesses a 

 selective bacteriostatic power which is in many important respects 

 the opposite of the selective power possessed by gentian violet. 

 Acid fuchsin and gentian violet will not, however, mix. I have 

 recently shown that neutral acriflavine possesses, like acid 

 fuchsin, a reverse selective bacteriostatic power; and acriflavine 

 and gentian violet will mix. Moreover the resultant substance 

 acts as a mixture. It is thus possible to fortify the weakness of 

 each of these two dyes with the strength of the other. If a mixed 

 bacterial emulsion containing B. pyocyaneus and B. anthracis be 

 exposed to gentian violet and streaked on plain agar a pure cul- 

 ture of B. pyocyaneus will result. If the same mixed emulsion 

 be exposed to neutral acriflavine a pure culture of B. anthracis 

 results. If the emulsion be exposed to a mixture of the two dyes 

 neither organism grows. The principle of supplementary selec- 

 tive bacteriostasis by means of mixtures is therefore established; 

 and the possibility of mixing at least certain dyes, whose selective 

 bacteriostatic powers are opposed, without the formation of a 

 new substance is demonstrated. 



