448 



Diphtheria 



Loffler bacilli, while forms closely resembling them, but more 

 uniform in size and shape, shorter in length, and of more homo- 

 geneous staining properties, with Loffler 's alkaline methylene- 

 blue solution, can with reasonable safety be regarded as pseudo- 

 diphtheria baciUi, especially if it be found that they produce an alka- 

 line rather than an acid reaction by their growth in bouillon. The 

 pseudo-diphtheria bacilli were found in about i per cent, of throats 

 examined in New York; they seem to have no relationship to diph- 

 theria, and are never virulent. 



Morphology. — This micro-organism bears a more or less marked 

 resemblance to BacUlus diphtherias, but dififers in certain particulars 

 that usually make it possible to recognize and identify it. It is 

 shorter and stouter, is straight, and usually slightly clubbed. It 

 usually stains intensely, and commonly shows but one unstained 

 transverse band. There are no flagella and no spores. 



Fig. 1 60.^ — Pseudo-diphtheria bacilli. 



Staining. — The orgam'sm stains intensely and more uniformly 

 than Bacillus diphtherias. When colored by Neisser's or^Roux's 

 method, no metachromatic end bodies can be defined. 



Cultivation. — ^The organism is usually discovered in smears made 

 for the diagnosis of diphtheria, and sometimes occasions considerable 

 confusion through its cultural similarities and morphologic resem- 

 blances to Bacillus diphtherias. It grows more luxuriantly upon the 

 ordinary culture-media than B. diphtherias. The colonies are larger, 

 less transparent and whiter, as seen upon agar-agar. In bouillon 

 there is more marked clouding and less marked pelhcle formation. , 

 Upon Loffler's blood-serum the cultures are too much alike to be 

 easily differentiated. 



G. F. Petri* found no substances in filtrates of cultures of Hof- 



* "Jour, of Hygiene," April, 1905, vol. v. No. 2, p. 134. 



