CHAPTER XI. 



DIPHTHERIA. 



BACILLUS DIPHTHERIA (KLKB 



General Characteristics. A non-motile, non-flagellate, non-spor- 

 ogenous, non-chromogenic, non-liquefying, aerobic, purely parasitic, 

 pathogenic, toxicogenic bacillus, cultivable upon the ordinary culture 

 media, staining by the ordinary methods and by Gram's method. 



In 1883 Klebs * demonstrated the presence of a bacillus 

 in the pseudo-membranes upon the fauces of patients 

 suffering from diphtheria, but it was not until 1884 that 

 Loffler f succeeded in isolating and cultivating it. The 

 organism is now known by both their names, and called the 

 Klebs-Loffler bacillus. 



Morphology. The bacillus is about the length of the 

 tubercle bacillus (1.5-6.5 /*), but about twice its diameter 

 (0.4-1.0 /*), has a slight curve similar to that which char- 

 acterizes the tubercle bacillus, and has rounded and usu- 

 ally clubbed ends. It does not form chains, though 

 two, three, and rarely four individuals may be found con- 

 joined; usually the individuals are separate from one an- 

 other. The bacillus is peculiar in its pleomorphism, for 

 among the well-formed individuals which abound in fresh 

 cultures a large number of peculiar organisms are to be 

 found, much larger than normal, some with one end en- 

 larged and club shaped, some greatly elongated, with both 

 ends similarly and irregularly expanded. These bizarre 

 forms probably represent an involution form of the organ- 

 ism, for, while present in perfectly fresh cultures, they 

 are much more abundant in old cultures where scarcely a 

 single well-formed bacillus can be found. Distinct polar 



* " Verhandlungen des Congresses fur innere Med.," 1883. 

 f " Mittheilungen aus dem kaiserlichen Gesundheitsamte," 2. 



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