CHAPTER XIX 



MYCOBACTERIACE^: THE BACILLUS OF DIPHTHERIA 



AND OTHER SPECIFIC BACILLI PARASITIC ON 



SUPERFICIAL MUCOUS MEMBRANES 



Bacillus (CorjTiebacteriiun) Diphtheriae.^ — Klebs in 1883 dis- 

 covered this organism in the microscopic study of pseudomem- 

 branes from fatal cases of epidemic diphtheria. LofHer in 1884 

 obtained pure cultures of the bacillus and by inoculating the 

 abraded mucous membrane of susceptible animals with his cul- 

 tures, he produced local lesions similar to those observed in human 

 diphtheria, in some instances followed by death or paralysis. 



B. dtphtherice occurs in the exudate (false membrane) which 

 occurs in the pharynx", larynx and adjacent m.ucous membranes 

 in epidemic diphtheria, on the mucous membranes of those who 

 have recovered from the disease and, much less commonly, on 

 the mucous membranes of healthy throats. It is a rod-shaped 

 organism extremely variable in size, shape and staining properties. 

 The width is ordinarily between 0.3 and 0.8/i and the length 

 varies from i to 6;u. The cell is straight or slightly curved and 

 very frequently of uneven diameter, with swelling at one end or 

 in the middle portion. The cell contents stain unevenly in 

 many of the cells. Many different morphological types are thus 

 presented which may be designated roughly as regular cylinders, 

 clubs, spindles and wedges according to form, and as uniformlv 

 pale, uniformly dark, regularly or irregularly banded or granular 

 according to internal structure of the stained cell. These varia- 

 tions in form and internal structure are best seen after staining 

 the bacillus with LofHer's methylene blue and are especially 

 valuable in the quick recognition of B. diphtheria as it grows in 

 the diphtheritic membrane or in culture on LofHer's blood serum. 



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