324 THE ALCALIGENES DYSENTERY TYPHOID 



the isolation of the organisms from the feces and their identification 

 by cultural and serological reactions. 



A bit of blood-stained mucus offers the best material for isolation 

 of the organisms: it should be washed two or three times in sterile 

 salt solution to remove extraneous organisms as far as possible, for 

 experience has shown that dysentery bacilli are frequently enclosed 

 in mucus. The mucus is then macerated in sterile broth, and if 

 possible incubated for one or two hours at 37 C. It is then spread 

 upon the surface of Endo-plates and incubated for eighteen to twenty- 

 four hours at 37 C. The colonies are precisely similar to those of 

 typhoid and paratyphoid bacilli; the final identification of the dysen- 

 tery bacilli is made by their cultural reactions (see page 316) and by 

 agglutination with specific sera of high potency. The rapid method 

 of isolating and identifying typhoid bacilli described on page 338 is 

 equally applicable to dysentery bacilli. The possibility of carriers 

 should be borne in mind when mild and atypical cases are under 

 consideration . 



Dissemination and Prophylaxis. Dysentery bacilli appear to be 

 widely distributed in certain areas of the temperate zone, and out- 

 breaks occur at varying intervals. Interepidemic years are occa- 

 sionally characterized by considerable numbers of atypical, mild 

 cases, and carriers are not uncommon. 1 



The organisms enter the body through the mouth and intestinal 

 tract, and leave it in the feces; consequently the method of trans- 

 mission of the disease is similar to that of typhoid and other excre- 

 mentitious disorders. There is some evidence that the disease may 

 be milk-borne; exclusively breast-fed infants are rarely or never 

 infected; bottle-fed babies of the same age may be infected in relatively 

 large numbers during years which exhibit an epidemic tendency of 

 bacillary dysentery. Zinsser 2 has produced evidence in favor of the 

 occasional milk transmission. The organism may also reach the body 

 by direct transmission through carriers, in hospitals, and through 

 contaminated water and food. Flies may also play a part in the spread 

 of the disease. 



The precautions to be observed are those for any intestinal infec- 

 tion. 



1 Kendall, Boston Med. and Surg. Jour., 1913, clxix, 7493; ibid., May 20, 1915. 



2 Proc. New York Path. Soc., 1907. 



