CHAPTER XX. 



THE DIPHTHERIA BACILLUS GROUP. 



THE DIPHTHERIA BACILLUS. 



BACILLI SIMILAR TO THE DIPHTHERIA 



BACILLUS. 



Bacillus Hofmanni. 

 Bacillus Xerosis. 

 Bacillus Hodgkini. 



THE DIPHTHERIA BACILLUS. 



Synonyms. Corynebacterium diphtherise, Klebs-Loffler bacillus. 



Historical. A small group of bacteria excrete soluble extracellular 

 toxins which produce specific disease. The first member of the 

 group to be isolated and studied was the diphtheria bacillus. Klebs 1 

 called attention to the very general occurrence of a bacillus of unusual 

 and characteristic appearance in the gray membranes usually present 

 in the throats of severe and fatal cases of diphtheria, and a year 

 later Loffler 2 isolated the organism in pure culture from several cases 

 of the disease. Loffler also obtained the diphtheria bacillus from the 

 throat of an apparently normal child, which led him to be very guarded 

 in attributing a specific relationship of the organism to the disease. 

 Subsequent studies by innumerable investigators have corroborated 

 these observations in every essential detail, and have demonstrated 

 conclusively that the diphtheria bacillus is the specific etiological 

 organism of diphtheria. Roux and Yersin 3 discovered the soluble 

 toxin of the diphtheria bacillus and reproduced the essential systemic 

 phenomena of the disease in experimental animals by injecting the 

 toxin freed from bacteria by filtration through porcelain. V. Behring 

 and Kitasato 4 made the very important discovery that the blood 

 serum of animals injected with gradually increasing amounts of diph- 

 theria toxin contained a specific antitoxin which would neutralize the 

 toxin; diphtheria antitoxin is one of the very few specific sera possess- 

 ing curative properties. 



Morphology. The diphtheria bacillus is one of the very few bacteria 

 which possess a characteristic morphology. The organisms are 



1 Verhandl. Kong. Inn. Med., Wiesbaden, II. Abt., 1883, 143. 



2 Mitt. a. d. kais. Gesamte, 1884, ii, 451. 



3 Ann. Inst. Past., 1888, 642. 



4 Deutsch. med. Wchnschr., 1890, xvi, 1113. 



