384 SPIRILLA, PATHOGENIC VIBRIONES, SPIROCHETE 



FIG. 154 



covered as its cause a comma-shaped bacterium which he named in 

 honor of Metchnikoff. The disease is generally fatal after forty- 

 eight hours, and its characterized by violent diarrhea without fever. 

 Postmortem examination shows the intestinal mucosa inflamed, its 

 epithelium desquamated; the contents of the intestines are fluid and 

 mixed with blood. The fluid contents contain enormous numbers of 

 comma-shaped bacteria, which very much resemble the spirillum of 

 Asiatic cholera in man (see below). For this reason the disease has 

 been called vibrio cholera or vibrio septicemia of chickens. The 

 spirillum of Metchnikoff, as found in the intestines of dead chickens, 

 occurs, in addition to the typical comma shape, also in shorter, 

 thicker specimens, which look almost like cocci. The vibrio is lively, 

 motile, and possesses one long slender flagellum. The organism 

 forms longer spirals in older cultures in which the individual commas 



adhere to each other in chains. 

 The spirillum of Metchnikoff 

 stains well with watery fuchsin, 

 and is Gram negative. It grows 

 well in the ordinary laboratory 

 media, and the cultures closely 

 resemble those of the spirillum 

 of Asiatic cholera. The vibrio 

 of chicken septicemia grows 

 rapidly on gelatin plates at room 

 temperature, and after twenty- 

 four to thirty hours has formed 

 pinhead-sized circular colonies, 

 which rapidly liquefy the me- 

 dium. The colonies under a low 

 power of the microscope appear 

 granular and yellowish or brown- 

 ish. Older cultures which have 

 been transplanted for a long 

 time on artificial media do not liquefy gelatin as rapidly as cultures 

 recently isolated from infected animals. The growth in gelatin stick 

 cultures is much more rapid than that of the vibrio of Asiatic cholera. 

 Bouillon is rapidly clouded and a fairly strong white pellicle forms on 

 the surface of the medium. On agar the vibrio forms a yellowish, on 

 potatoes a yellowish-brown, growth. The vibrio of Metchnikoff cannot 

 be safely distinguished by any of its cultural characteristics from the 

 vibrio of Asiatic cholera. Both also form indol and nitrites in bouillon, 

 and these upon the addition of a few drops of chemically pure sulphuric 

 acid give a red color reaction. The differentiation between the two 

 organisms, however, can be made by animal experiments. The 

 vibrio of Metchnikoff kills pigeons if injected into the thoracic muscles 

 within twenty-four hours. Postmortem examination of the dead birds 

 shows the injected muscle swollen, yellowish in color, and infiltrated, 



Spirillum of Asiatic cholera smear from the 

 intestines of a man dead from cholera. X 1000. 

 (Author's preparation.) 



