SPECIAL BACTERIOLOGY 
157 
It is very frequently encountered in the laboratory 
work and may be confused with typhoid bacillus, but 
cultural studies and agglutination make its differentia¬ 
tion easy. 
The Dysentery Bacilli 
Dysentery is an infectious disease characterized by 
severe diarrhea. 
♦ , 
Fig. 29.—Dysentery bacilli, x 1000. (Park and Williams —Pathogenic Bac¬ 
teria and Protozoa.) 
The first to discover the organism was a Japanese bac¬ 
teriologist, Shiga (1898). 
There are three organisms—the Shiga type, the “ Y ” 
(Hiss-Russell) type, and the Flexner type. All three 
types morphologically resemble each other and the rest 
of the typhoid-colon-dysentery group. 
The differentiation and the diagnosis is made on cul¬ 
tural (sugar fermentation) characteristics and aggluti¬ 
nation, as described in Chapters XIII, XIV and XV. 
