142 ESSENTIALS OF BACTERIOLOGY 



Widal's serum test, as used in typhoid, is applicable in the 

 diagnosis of cholera, using cholera cultures in place of the 

 typhoid. 



Staining. They are colored well with watery anilin solu- 

 tions. The flagella can be well seen by staining according to 

 the flagella stain. 



Patho genesis. Experiment animals are not subject to cholera 

 Asiatica, but by overcoming two obstacles, Koch has produced 

 choleraic symptoms in guinea-pigs. Nicati and Rietsch pre- 

 vented peristalsis and avoided the acidity of the stomach-juices 

 by direct injection into the duodenum, after tying the gall-duct. 

 Koch alkalinizes the gastric juice with 5 c.c. of 5 per cent, 

 solution of sodium carbonate, and then injecting 2 grams of 

 opium tincture for every 300 grams of weight into the peritoneal 

 cavity, paralyzes peristalsis. The cholera culture then intro- 

 duced through a stomach-tube, the animals die in forty-eight 

 hours, presenting the same symptoms in the appearance of the 

 intestines as in cholera patients, the serous effusion containing 

 great numbers of spirilla. 



Manner of Infection in Man. Usually through the alimen- . 

 tary tract, with the food or drink, the intestinal discharges of 

 cholera patients having found entrance into the source of drink- 

 ing water. Soiled clothes to fingers, fingers to the mouth, etc.; 

 torpid catarrhal affection of the digestive tract predisposing. 

 The spirilla are not found in the blood or any organ other than 

 the intestines, the tissue of the small intestines. They are also 

 found in the vomit and the intestinal contents. 



Products. "Cholera red." When chemically pure nitric or 

 sulphuric acid is added to nutrient peptone cultures of the 

 cholera bacillus, a rose-red color is produced. This will not take 

 place with other bacilli unless nitrous acid is present. The 

 cholera bacillus forms nitrites from the nitrates present in the 

 media, and also indol. The mineral acid splits the nitrites, 

 setting free nitrous acid, which, with the indol, forms the red 

 reaction. This pigment has been isolated and extracted and 

 called " cholera red." A ptomain, identical with cadaverin, and 

 several other alkaloids, have been obtained from the cultures. 



