DIPHTHERIA BACILLUS 1 91 



toxin may be discovered in the blood, by mixing it with toxin of 

 known strength, and injecting it into guinea pigs. If these survive 

 a large lethal dose of the toxin, it is safely presumed that anti-toxin 

 was present in the serum abstracted. 



Passive artificial immunity is induced by injecting anti-toxin in 

 the bodies of persons exposed to diphtheria. It is most effective 

 but is short lived, lasting only a few weeks. Serum therapy (see 

 anti-toxin in previous chapter). If there is one natural specific 

 cure for any disease, it is diphtheritic anti-toxic serum, which is 

 prepared by immunizing horses with toxin, and abstracting their 

 blood. This is measured in units, 1,000 to 5,000 units forming 

 a dose. The earlier it is given, the better are the chances of recov- 

 ery. As a prophylactic, from 600 to 1,000 units should be used. 

 As many as 100,000 units have been injected in a single patient. No 

 case is too trivial, or too far advanced in which to use it. The 

 serum is anti-toxic, and not bactericidal. 

 Wassermann has prepared a serum that is 

 bactericidal, and is designed to destroy the 

 bacilli. 



Pseudo-diphtheria bacilli, which mor- 

 phologically and culturally resemble the true 

 bacilli, have been described. They are not 



pathogenic, in the sense of producing exuda- FIG. 67. Diphtheria 



,. , , . , ,. , bacilli stained with 



tive diphtheria, and are believed to be atten- Loffler's blue. Striped. 



uated diphtheria bacilli by many observers. (Greene's Medical 

 The diagnosis of diphtheria by culture is an 

 important measure. It depends upon the rapid growth of the 

 bacilli upon Loffler's blood serum. Of all the various organisms 

 found in the throats of patients with diphtheria, the diphtheria 

 bacilli outstrip them in rapidity of growth. After eight to twelve 

 hours, the serum inoculated with the smear from the false mem- 

 brane is covered with fine granular colonies of pure diphtheria 

 bacilli. After twenty-four, or more hours, the other organisms 

 present overgrow the diphtheria colonies. A sterile swab of cot- 



