212 BACTERIA 



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 pre- 

 pared a serum that is bactericidal, and is designed to destroy the 

 bacilli. 



Pseudo-diphtheria bacilli, which morphologically and culturally 

 resemble the true bacilli, have been described. They are not 

 pathogenic, in the sense of producing exudative diphtheria, and 

 are believed to be attenuated diphtheria bacilli by many observ- 

 ers. 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 membrane 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 cotton, or a 

 stick, is rubbed over the false membrane, or throat, and then over 

 the serum; the latter is incubated, and the culture examined after 

 eight or twelve hours, by staining with LorHer's blue. If curved, 

 clubbed, irregularly stained bacilli are found, especially if they 

 contain dark polar granules, and are generally uneven in size and 

 bizarre, it may be safely considered that they are diphtheria 

 bacilli. Gram's stain may be needed to confirm the diagnosis 

 occasionally, or it may be necessary to inoculate guinea pigs. 

 This may be done by inoculating the whole throat culture and 

 plating out from the local inflammation, or the organisms may be 

 isolated directly by plating and then injected into animals. 

 It is well to check up the test by immunizing one animal with 

 200 units of anti-toxin before the culture is given, using another 

 guinea pig unprotected. This serves as a control upon toxin 

 production. Virulent bacilli will kill a guinea pig of 250 grams 



