CHAPTER XV. 

 SPIRILLA. 



SPIRILLUM CHOLERA ASIATICS. 



The cholera spirillum was discovered by Koch in 1883 in 

 the defalcations of sufferers from cholera. It is also called 

 the " comma bacillus " and the " Vibrio cholerae." 



Description. Short, slightly curved rods, 1-5 to 2 micra 

 long by 0-5 micron thick. Ex. C In pairs, may form an 

 S-shape, thus * y Actively motile, and swim like fish in 

 lines, thus 5 5 = 5 . Possess one flagellum, situated at one 

 end (monotrichal) . Non-sporing ; not phosphorescent ; 

 Gram-negative. Markedly aerobic, but can grow anaero- 

 bically. Optimum temperature 37 C. ; growth usually 

 ceases at 16 C. Gelatin-liquefying. Give nitroso-indol 

 reaction with sulphuric acid within twenty-four hours. 



Culture. Grows readily on all usual media, but better if 

 alkaline, and except on potato even at room temperature ; 

 characteristic on gelatin plates and in broth. On gelatin 

 plate : minute whitish points in twenty-four to forty-eight 

 hours ; surface when magnified is coarsely granular and 

 furrowed. Liquefaction follows and the colony sinks, 

 showing a ring around. In gelatin stab : liquefaction 

 begins at the surface, with gradual formation of a funnel 

 of liquefaction. In broth : rapid clouding occurs with 

 wrinkled pellicle on top, composed of spirilla in a very 

 actively motile condition. In milk : growth but no visible 

 change. In peptone water : rapid growth with production 

 of indol, and reduction of nitrate to nitrite, hence a few 

 drops of pure sulphuric acid will give a red colour the 

 so-called cholera-red reaction. Also given in broth culture, 

 and in both in twenty-four hours, owing to rapid growth. 

 Not absolutely specific, as it is given also by Sp. Metch- 

 nikovi. Blood serum is rapidly liquefied. In sugar media : 

 no gas is formed, but acid with glucose. Does not pro- 

 duce haemolysis, though very similar species do. Does not 

 multiply in water. 



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