454 INFECTION AND RESISTANCE 



PRACTICAL, CONSIDERATIONS CONNECTED WITH DIPHTHERIA ANTI- 

 TOXIN PRODUCTION AND STANDARDIZATION 



The conditions which govern the active production of toxins by 

 bacteria in culture media are not only of great theoretical interest 

 but possess unusual practical value in that the most important factor 

 for the successful production of a strong antitoxin consists in the 

 preliminary preparation of a potent toxin. The bacterial true toxins 

 are all "exotoxins" in that they are soluble, moderately diffusible 

 substances which pass readily from the bacterial bodies to the en- 

 vironment, and for this reason can be obtained most readily by the 

 cultivation of the bacteria upon fluid media and subsequent filtration 

 of the cultures through earth or porcelain filters. 



The choice of culture or strain is an important element in this 

 procedure, since within the same species of toxin-producing micro- 

 organisms there is much variation in the speed and energy of toxin 

 production. Thus for unknown reasons some strains of diphtheria 

 bacilli will far outstrip others in this respect. An excellent illustra- 

 tion of this is the experience of Park and Williams 14 with two diph- 

 theria cultures a very virulent and a very weak one. Of the 

 former, 0.002 c. c. of a forty-hour bouillon culture killed a guinea 

 pig, while of the latter 0.1 c. c. of a similar culture was necessary 

 for the same result. 



In the case of tetanus, cultural differences do not seem to be as 

 common. Individual strains also may gain or lose in toxin-pro- 

 ducing powers, according to the method of handling them which is 

 practiced. It is stated, 15 for instance, that a diphtheria culture will 

 lose in energy of toxin production if permitted to grow without suffi- 

 ciently frequent transplantation. However, transplanted on solid 

 media with reasonable frequency, these bacteria show a remarkably 

 constant toxin production. A well-known strain, the Park-Williams 

 No. 8, now in use in many antitoxin laboratories throughout the 

 world, has persisted for over 15 years in producing a strong toxin. 

 There are occasional strains among toxin-forming species which are 

 entirely devoid of this property. Diphtheria bacilli which were 

 virulent while possessing all the other cultural characteristics of the 

 group have been described, but appear, from the experience of the 

 writer, to be rather uncommon. 16 Of tetanus bacilli little is known 

 in this respect. 



Given a powerfully toxic strain of the proper bacteria the 

 method of cultivation is also of great importance in influencing the 

 eventual yield of poison. These relations have naturally been stud- 

 ied with the greatest care in the case of diphtheria and tetanus 



14 Park and Williams. "Pathogen. Micro-organ./' N. Y., 1910. 



15 Park and Williams. Loc. cit. 



16 Zinsser. Jour. Med. Res., N. S., Vol. 12, 1907. 



