BACTERIAL METABOLISM WITHIN THE BODY 673 



derivatives, and the absence of such significant products [toxin, indol or 

 enxyme] in the glucose-nitrogenous media indicates the importance of the 

 source of energy as a determining factor in directing the type of action 1 

 of the microbe. 



5. The Specificity of Action of Pathogenic Bacteria 

 and Its Relation to Proteins and Carbohydrates 



From what has been stated previously, it would appear that pathogenic 

 and parasitic bacteria produce significant or specific nitrogenous waste 

 products incidental to their utilization of protein or protein derivatives 

 for energy. Thus, diphtheria, typhoid, dysentery, cholera, paratyphoid; 

 glanders, colon, proteus, and many other pathogenic microbes produce 

 specific toxins or other characteristic nitrogenous products in protein en- 

 vironments from which utilizable carbohydrates are excluded. 



On the contrary, when in addition to protein utilizable carbohydrates 

 are also available as sources of energy, these same organisms act upon the 

 latter instead of the former, and produce therefrom acidic products, chiefly 

 lactic and, to a lesser extent, acetic acid. 



In other words, the simple addition of glucose to cultures of patho- 

 genic bacteria, other conditions remaining the same, brings about a strik- 

 ing alteration of the nature of their metabolic products. In place of toxins, 

 phenols, katol, and other protein derivatives, specific or characteristic 

 of each individual microbe, all produce innocuous lactic and acetic acids. 

 These formidable incitants of disease in man have become potentially 

 lactic acid bacteria. Grown in glucose media, therefore, the diphtheria, 

 typhoid, cholera and other pathogenic bacteria become the qualitative 

 equivalents of the Bulgarian lactic acid bacillus. 8 



Stated differently, it may be said that the specificity of action of the 

 vast majority of bacteria pathogenic for man is dependent upon their 

 utilization of protein for energy (Kendall). 



Fats play a very minor part in the metabolism of pathogenic bacteria, 

 other than those of the acid-fast group, which includes the tubercle and 

 leprosy bacilli. The effects of utilizable fats are comparable to the carbo- 

 hydrates rather than the proteins, however, so far as their energy rela- 

 tionships are concerned. 



The toxicity of the cellular substance of bacteria is not considered in 

 this connection, nor is it relevant, Available evidence indicates that the 

 cytoplasm of non-pathogenic bacteria, as for example Bacillus prodigiosus, 

 may be many fold more deadly to animals than that of such formidable 



8 It is obvious that a continuous supply of utilizable carbohydrate must be avail- 

 able; when the sugar is used up, provided the organisms are not killed by the products 

 resulting from fermentation, they will at once attack the protein again and generate 

 their specific protein decomposition products. 



