THE DIPHTHERIA BACILLUS 401 



faciei. 1 Rarely, false membranes are found on the genitalia or in 

 cutaneous wounds, in the latter case producing a true wound diph- 

 theria. 2 The association with certain other organisms, particularly the 

 streptococcus, the staphylococcus, and B. coli, appears to increase the 

 virulence of the diphtheria bacillus. 3 



Diphtheria is a generalized toxemia with a local infection. The 

 bacilli cause coagulation necrosis of the superficial cells, and an inflam- 

 matory membrane consisting of a serofibrinous exudate in which 

 fibrin and leukocytes are prominent, together with epithelial cells, 

 pyogenic cocci, and diphtheria bacilli in the deeper layers adjacent 

 to the denuded epithelium. At times the membrane strips off without 

 serious injury to the underlying epithelium, but in severe cases the 

 membrane tears away, leaving a bleeding raw surface. 



There are three principal types of diphtheria: the faucial, laryngeal, 

 and tracheal. The incubation period is from two days to a week. An 

 important sequela is the postdiphtheritic paralysis, which is sup- 

 posed to be caused by the toxone component of the diphtheria toxin. 

 This is anatomically a toxic neuritis and it occurs in from 10 to 20 

 per cent, of all cases of diphtheria from 2 to 4 weeks after the attack. 

 There is no apparent relation between the severity of the attack and 

 the paralysis. The pharynx is most commonly affected, next in order 

 the eyes, leading to strabismus (ptosis). In a smaller number of cases 

 the heart is affected. When the heart is affected the patients not 

 infrequently drop dead as the result of cardiac failure. The early 

 use of antitoxin usually prevents or greatly modifies the development 

 of postdiphtheritic paralysis. 



Bacteriological Diagnosis. The principle involved in the bacterio- 

 logical diagnosis of diphtheria (and the diagnosis can only be definitely 

 established by bacteriological examination) is to make cultures from 

 the suspected lesions on Loffler's alkaline blood serum, to incubate 

 the culture from twelve to eighteen hours at 37 C., to stain the 

 resulting growth with Loffler's methylene blue, and to diagnose the 

 organisms by their characteristic morphology. 



The Technic of Inoculation. Rub a sterile swab on the under surface 

 of the diphtheritic membrane, avoiding extraneous organisms and 

 avoiding touching the tongue or other parts of the mouth. Smear 

 this infected swab gently over the surface of the serum, rotating the 



1 Freymouth, Deutsch. med. Wchnschr., 1898, No. 15. 



2 Schottmuller, Deutsch. med. Wchnschr., 1895, p. 273. 



3 Theobald Smith, Medical Record, May, 1896. 

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