Spirillum Cholerae Asiaticae is a motile, flagellated, non-sporogenous, liquefying aerobic, and facultative anaerobic spirillum; found in short arcs, spirals, and "comma" forms. About 0.8 µ long. Has a single end flagellum. Is found in the feces, never in the blood or tissues, of those suffering from Asiatic cholera.

Stains

Usual methods, but not by Gram's.

Culture

Easily cultivated. On gelatin plates colonies appear in lower layer as small white dots. Extend to surface, causing liquefaction. Are granular. Gelatin stab cultures show liquefaction gradually extending from the surface downward. Gives rise to an inverted cone with an air-bubble at the upper end. In liquid media the presence of indol and of nitrites is shown by the addition of one or two drops of chemically pure sulphuric acid, a reddish color being produced. Forms acid, but does not coagulate milk.

The spirilla resembling that of cholera are the following:

Finkler-Prior Spirillum

Similar in shape, but shorter and stouter. Actively motile. Growth rapid. Does not produce indol. Causes extensive liquefaction of gelatin. Is found in the feces of cholera morbus.

Fig. 97. - Cholera Spirilla, showing Flagella (Muir and Ritchie).

Vibrio Tyrogenum

Found in old cheese. Similar in form. Growth and liquefaction faster than S. cholera, but less rapid than Finkler. Is actively motile and has an end flagellum. Forms yellow, irregular, distinctly circumscribed colonies.