DIPHTHERIA BACILLUS. 353 



the streptococcus being particularly active in this 

 respect, often opening the way for the invasion of the 

 Loffler bacillus into the deeper tissues or supplying 

 needed conditions for the development of its toxin. 

 Thus diphtheria is not always a primary, but often a 

 secondary disease, following some other infection, as 

 measles or scarlet fever. In most fatal cases of bron- 

 chopneumonia following laryngeal diphtheria we find 

 not only abundant pneumococci or streptococci in the 

 inflamed lung areas, but also in the blood and tissues 

 of the organs. As these septic infections due to the 

 pyogenic cocci are in no way influenced by the diph- 

 theria antitoxin, they frequently are the cause of the 

 fatal termination. Other bacteria cause putrefactive 

 changes in the exudate, producing alterations in color 

 and offensive odors. 



Pseudomembranous Exudative Inflammations Due to 

 Bacteria other than the Diphtheria Bacilli. The diph- 

 theria bacillus, though the most usual, is not the only 

 micro-organism that is capable of producing pseudo- 

 membranous inflammations. There are numerous bac- 

 teria present almost constantly in the throat secretions, 

 which, under certain conditions, can (ause local lesions 

 very similar to those in the less marked cases of true 

 diphtheria. The streptococcus and pneumococcus are 

 the two forms most frequently found in these cases, 

 but there are also others which, under suitable condi- 

 tions, take an active part in producing this form of 

 inflammation. Some of these bacteria do not develop 

 on artificial media, so that we know little of their 

 characteristics. Among these is a long slender bacillus 

 which is occasionally found in great abundance in the 

 middle layers of pseudomembranes when the diphtheria 



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