520 PATHOGENIC MICROORGANISMS 



Diphtheria Toxin. 1 Animals and man infected with B. diphtheriae 

 show evidences of severe systemic disturbances and even organic de- 

 generations, while the microorganism itself can be found in the local 

 lesion only. This fact led even the earliest observers to suspect that, 

 in part at least, the harmful results of such an infection were attrib- 

 utable to a soluble and diffusible poison elaborated by the bacillus. The 

 actual existence of such a poison or toxin was definitely proved by 

 Roux and Yersin 2 in 1889. They demonstrated that broth cultures in 

 which B. diphtheria had been grown for varying periods would remain 

 toxic for guinea-pigs after the organisms themselves had been removed 

 from the culture fluid by filtration through a Chamberland filter. 



METHODS OF PRODUCTION or DIPHTHERIA TOXIN. While toxin can 

 be produced with almost all of the virulent diphtheria bacilli, there is 

 great variation in the speed and degree of production, dependent upon 

 the strain of organisms employed and upon the ingredients and reaction 

 of the medium upon which they are grown. Most laboratories possess 

 one or several strains of bacilli which are empirically 'known to be es- 

 pecially potent in this respect. One of the most extensively used, not 

 only in this country, but in Europe as well, is the strain known as 

 "Culture Americana," or " Park- Williams Bacillus No. 8," an organism 

 isolated by Dr. Anna Williams of the New York Department of Health 

 in 1894. Throughout more than ten years of cultivation this bacillus 

 has retained its great power of toxin production. 



Because of the severity of cases of diphtheria in which the diphtheria 

 bacilli were associated with streptococci, many observers were led to 

 believe that the presence of streptococci tended to increase the toxin- 

 producing power of B. diphtheriae. Experiments by Hilbert^ Theobald 

 Smith, 4 and others seem to have given support to this view 1 . 



The medium most frequently employed for the production of toxin is 

 a beef-infusion broth. There are minor differences of opinion as to the 

 most favorable constitution of this medium for the production of toxin. 

 All agree, however, in recognizing the importance of pepton, without 

 which, according to Madsen, 5 no satisfactory toxin has yet been pro- 

 duced. This is added in proportions of from one to two per cent. The 

 presence of sugars in the medium is not desirable in that it leads to acid 

 production; L. Martin 6 removes the sugars from the meat by fermen- 



1 Loeffler, Cent, f . Bakt., 1887. 2 Roux and Yersin, loc. cit. 



3 HUbert, Zeit. f. Hyg., xxix, 1898. 4 Smith, Medical Rec., May,1896. 



6 Madsen, Kraus und Levaditi, "Handbuch. d. Technics," etc., 1907. 

 * L. Martin, Ann. de 1'inst. Pasteur, 1897.' 



