258 DIFCOMANUAL 



with a reasonable degree of certainty. For example, diphtheria toxin is produced 

 under practical conditions only when the organism grows as a film on the surface 

 of liquid media. Media supporting such growth are, therefore, essential. Accord- 

 ing to Robinson and Rettger^ the toxin factors are probably supplied by the 

 proteoses and polypeptides. Gibbs and Rettger^ have shown that in sugar-free 

 media toxin production occurs only when proteoses are present. Toxin produc- 

 tion, therefore, is definitely dependent upon the composition of the peptones 

 present in the medium. ' 



Hazen and Heller^ have shown that diphtheria toxin of high Lf can be pro- 

 duced in a "bob veal" infusion medium containing 2 per cent Proteose Peptone, ^ 

 0.15 per cent dextrose and 0.3 per cent maltose. Pope^ has also used Proteose 

 Peptone in his semi-synthetic media for diphtheria toxin production, and Bayne- 

 Jones^ was able to obtain a diphtheria toxin having more than 300 M.L.D. per 

 milliliter in a synthetic medium to which he added 2 per cent Proteose Peptone. 

 Semi-synthetic media containing Proteose Peptone have also been employed by 

 Kirkbride, Berthelsen and Clark^ and by Wadsworth and Wheeler.i^ 



Proteose Peptone quickly became established as a suitable peptone for use in 

 the production of diphtheria toxin, and it is now employed almost universally in 

 the biological laboratories engaged in the preparation of diphtheria toxin for 

 antitoxin, toxin-antitoxin and toxoid. In addition to the references already cited, 

 mention should also be made of the work of Hewitt,^^ Bunney^^ ^nd Povitsky, 

 Eisner and Jackson.^^ 



Proteose Peptone is also valuable in the elaboration of other bacterial toxins 

 as well as that of C diphtheriae. Kirkbride and Wheeler^* used this peptone 

 successfully for the production of scarlet fever toxin, and Veldee^^ has shown that 

 a combination of Proteose Peptone and Bacto-Peptone with inorganic salts is an 

 excellent medium for elaboration of scarlet fever toxin of uniformly high potency. 

 Nelson^^ used Proteose Peptone for elaboration of toxin by Clostridium hotuli- 

 num, Kneeland and Dawes^'^ for that of the pneumococcus, and Hanks and 

 Rettger^s that of Salmonella pullorum. 



Proteose Peptone is a satisfactory nutriment for the propagation of many 

 bacteria as may be seen from the work of Chapman, Lieb, Berens and Curcio,^^ 

 and Dolman and Wilson-^ on the pathogenic staphylococci, Eldering and Ken- 

 drick^i on Hemophilus pertussis, Tittsler and Lisse22 on S. pullorum, and Scott^* 

 on Pasteurella multocida. This peptone, furthermore, is a valuable ingredient of 

 culture media designed for such special biological reactions as the methyl red 

 and Voges-Proskauer tests,24'25 bacterial fluorescence^^ and pigment production.^^ 

 Many factors account for the suitability of Proteose Peptone for cultivating the 

 fastidious types of bacteria; among them are the availability of its nitrogenous 

 components and its buffer range. These factors also aid in establishing favorable 

 conditions for maintaining the virulence of the cultures and for the elaboration 

 of bacterial by-products. 



A method for the in vitro testing for virulence of C. diphtheriae was described 

 by Elek^s and also a modification of this method was given by King, Frobisher 

 and Parsons.2^ King, Frobisher and Parsons^^ and Frobisher, King and Parsons^^ 

 continuing their studies on the in vitro test for virulence of C. diphtheriae simpli- 

 fied their basal medium, and a comparative study of peptones showed Proteose 

 Peptone to give the most satisfactory results. Handley^- described a selective 

 medium for the identification and isolation of C. diphtheriae, and in an exhaus- 

 tive study of available peptones found that Proteose Peptone, Difco was more 

 suitable than any other peptone tried for the preparation of his medium. Mc- 

 Vickar^^ in a study of the factors important for the growth of Histoplasma 

 capsulatum reported that of the 18 peptones used, Proteose Peptone, Difco gave 

 the best growth of the organisms. 



