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APPLIED BACTERIOLOGY 



CHOLERA. 



Discovery and morphology of the organism — Growth on media — Dis- 

 tinction from the Finkler-Prior baoUlus — Bacteriological diagnosis of 

 cholera — Indol reaction — Variations in organisms — Occurrence and 

 distribution — Transmission of the disease — Pathogenesis — Haffkine's 

 antitoxin treatment. 



The Spirillum cholera Asiatictz, the organism producing 

 true Asiatic cholera, is generally known as Koch's ' comma ' 

 bacillus. This organism was discovered by Koch in 1884, 

 in the excreta of persons suffering from cholera. The 

 researches of Koch in Egypt and India during 1884 showed 

 that this spirillum is constantly present in the contents of 

 the intestine of cholera patients, but is not found in the 

 healthy subject. Koch's ' comma ' bacillus does not form 

 spores; it is killed by drying; its thermal death-point is 

 about 50° C, and it is very rapidly killed by sunlight. 



Method of Staining. — The cholera spirillum stains best 

 with an aqueous solution of fuchsine or gentian violet. It 

 is not stained by Gram's method. 



The bacillus grows readily on almost all media, whether 

 oxygen is admitted or not, and after it has developed a 

 saprophytic habit is much less easily killed by disinfectants 

 than when fresh from the stool. 



The Finkler-Prior spirillum is the only one which is at 

 all likely to be confounded with Koch's ' comma.' It is 

 found in large numbers in the stools in English cholera — 

 cholera nostras, cholera infantum. 



The general behaviour of the two organisms on different 

 media is distinctive, as is seen in the following table : 



Care must be taken that the broth is faintly alkaline. 



