Vibrio Deneke, Deneke (1885). 

 SPIRILLUM tyrogenum; spirillum of deneke; cheese spirillum. 



Origin.— From old cheese. 



Form.— Short, slightly bent rods: may form spirals. Resem- 

 bles somewhat the cholera vibrio but it is smaller and the comma-form 

 is less pronounced. 



Motility.— Very motile. Single flagellum. 



Sporulation. — Not known. 



Anilin dyes.— Stain readily. 



Growth. — Is quite rapid, but less than that of the Finkler-Prior 

 vibrio. On some gelatin media it liquefies very slowly or not at all. 

 It tends to die out rapidly. 



Plates.— The colonies which develop on gelatin plates are yellowish, liguefy and the 

 plate as a whole may resemble somewhat that of the cholera vibrio, but the liquefaction is 

 more rapid. Under the microscope they are seen to be circular, sharply bordered and 

 coarsely granular, the center is yellowish-green and later becomes dark yellow. 



Sial/ culture. — Growth takes place in gelatin tubes along the entire line of inocula- 

 tion; funnel-shaped liquefaction. The mass of bacteria settles to the bottom while on the 

 surface a yellowish scum or layer forms. 



Streak culture. — On a^ar a thin yellowish growth develops along the line of inocula- 

 tion. On potato, in the incubator, it forms a delicate, yellowish covering which frequently 

 contains well-formed spirals. Frequently, no growth. On blood-serum, it soon produces, 

 liquefaction. 



Bouillon cultures are cloudy but form no scum. They do not give the indol reaction 

 unless a nitrite is added. 



Milk is slowly coagulated. 



Oxygen requirements. — Is a facultative anaerobe. 



Temperature. — Grows at ordinary temperature, also at 37°. 



Behavior to gelatin. — Liquefies more rapidly than the cholera 

 vibrio, but less than that of Finkler-Prior. The power of liquefac- 

 tion is subject to very great variation. On prolonged cultivation it 

 may almost disappear— attenuation. 



Aerogenesis. — Not observed, even on glucose media. 



Pathogenesis. — It is less pathogenic to guinea-pigs than the 

 Finkler-Prior vibrio. It is to be considered as a saprophyte. 



Diagnosis of Asiatic cholera. — When making microscopic exam- 

 inations of intestinal contents it should be remembered that comma 

 bacilli and spirals, which are derived from the normal mouth, may be 

 present. A positive recognition of the cholera vibrio can only be 

 effected by cultural methods such as are given in Chapter XIII. This- 

 procedure should be employed not only to effect a diagnosis, but also- 

 to ascertain and confirm tne absence of the vibrio from the intes- 

 tines of convalescents. Although they usually disappear in about a 

 week they may, however, persist for 4 or even 7 weeks, in which case 

 precaution must be taken to prevent the spread of the infection. 

 Again, in cholera times apparently healthjr persons may contain the 

 comma bacillus. In such cases active immunity, or unfavorable 

 microbic associations may prevent development of this organism. 



346 



