CHAPTER XII 

 DIPHTHERIA 



Bacillus Diphtheria (Klebs-Loffler) 



General Characteristics. — A non-motile, non-flagellate, non-sporogenous, 

 non-chromogenic, non-liquefying, aerobic, purely parasitic, pathogenic, toxico- 

 genic bacillus, cultivable upon the ordinary culture media, staining by the ordi- 

 nary 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 Lofilert 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 /i), but about twice its diameter (0.4-1.0 /*), has a 

 slight curve similar to that which characterizes the tubercle bacillus, 

 and has rounded and usually clubbed ends. It does not form 

 chains, though two, three, and rarely four individuals may be found 

 conjoined; usually the individuals are separate from one another. 

 The bacillus has no flageUa, it is non-motile, and does not form spores. 

 Distinct polar granules can be defined at the ends of the bacilli. 

 Occasional branched forms are observed, though Abbott and Gilder- 

 sleevej do not regard branching as a phase of the normal develop- 

 ment of the organism and do not find it common upon the standard 

 culture media. 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 enlarged and club shaped, some 

 greatly elongated, with both ends similarly and irregularly expanded. 

 These probably represent an involution form of the organism, for 

 they are present in perfectly fresh cultures. 



The involution of the diphtheria bacillus seems to occur in pro- 

 portion to the rapidity of its growth. Upon LofHer's serum mix- 

 ture, which seems best adapted for its cultivation, the involution 

 of the organism takes place with great rapidity, so that large clubbed 

 organisms and large organisms with polar granules are very common. 

 On the other hand, upon agar and glycerin agar-agar, where the 

 organism grows very slowly, it usually appears in the form of 

 short spindle and lancet shapes. So different are these forms that 



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

 t " Mittheilungen aus dem kaiserlichen Gesundheitsamte," 2. 

 t "Centralbl. f. Bakt.," etc., Dec. 18, 1903, Bd. xxxv, No. 3. 

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