3 so SPECIFIC MICRO-ORGANISMS 



The bacteriological diagnosis depends altogether upon the 

 recognition of the cholera germ in the feces. During an epidemic 

 of the disease a probable diagnosis in the individual case may be 

 made by mere microscopic examination of stained preparations 

 of the mucous flakes in the stools. The presence of abundant 

 curved rods arranged parallel to each other is sufficient for a 

 probable diagnosis. The problem presents itself in a different 

 phase when it is necessary to recognize the first case of cholera in 

 a given locality. Here it is necessary to follow up the microscopic 

 diagnosis by cultures on gelatin plates, agar plates and in pepton 

 solution, and the identification of the cultured organisms by 

 agglutinating them with a known cholera-immune serum in high 

 dilution (i :iooo). The serum should be powerful enough in a 

 dilution of i: 10,000 to agglutinate very definitely the culture 

 used in producing it. The examination of immigrants for the 

 detection of cholera carriers also requires culture work. The 

 stool should be passed naturally, but a dose of salts is permissible 

 if there is too great delay. About i gram of feces is mixed with 

 50 c.c. of sterile pepton solution 1 in a flask, and this is incubated 

 a t 37 C. f r six to eight hours. A stained preparation is then 

 made from the surface film of the flask. If no curved rods are 

 found in it, the specimen is probably negative. A loopful of the 

 surface film should nevertheless be transferred to a tube of pepton 

 solution which is incubated for six hours and again examined 

 microscopically. If curved rods are found microscopically on 

 the surface film of either the first or second culture, the problem 

 of differentiating between the cholera vibrio and other similar 

 organisms is presented. Plate cultures on gelatin at 22 C. and 

 on agar at 37 C. should be made and at the same time the trans- 

 plantation to fresh pepton solution should be continued at six- 

 hour intervals. After eighteen hours, one examines the plates 

 for typical colonies and subjects these to agglutination tests with 

 specific serum of high titre. The bacteria from the surface film 

 of the pepton solution are also tested in the same way. A rapid 



1 Pepton 10, NaCl 10, NaNO 3 o.i, NaCO 3 0.2, distilled water 1000. 



