THE GROUP OF THE DYSENTERY BACILLI 355 
Products of Growth. — Chemical Prodvci^.— Plain broth cultures of 
Shiga and many strains of Flexner bacilh do not contain indol or 
phenols, even after prolonged incubation. The statements with refer- 
ence to indol production in the group, however, are somewhat con- 
flicting, particularly with reference to the Flexner group of organisms. 
Morgan and others^ have stated that Hexner bacilli produce indol; 
on the other hand, Kendall, Bagg, Day and Walker^ have isolated 
over 200 strains of Flexner bacilli from dysenteric cases and hare 
found that indol is not formed by the great majority of them. These 
strains were identified by their cultural reactions and by agglutination 
with a specific Flexner serimi of high ])otency. Dopter^ has found 
that strains of Flexner bacilli obtained from difierent sources, which 
were identical culturally and agglutinated the same with specific sera, 
vary in indol production, some producing indol, others not producing it. 
Acid Production in Carbohydrate Media.— AW members of the dysen- 
tery group agree in two important characteristics: they do not form 
gas in carbohydrate media, and form acid in glucose. Lentz"* has 
called attention to an important cultural differentiation of the Flexner 
and Shiga bacillus, the former producing acid in mannitol, the latter 
not fermenting this alcohol. Further study has shown that the 
fermentation of certain carbohydrates is important in the recognition 
of the various types. The fermentation and other cultural reactions 
of members of the dysentery })acillus group are shown in the table 
on page 353. The members of the dysentery group produce an initial 
acidity in milk; fermentation of the small amount of glucose, amounting 
to about 0.1 per cent which is found in fresh milk (Theol^ald Smith),* 
followed by an alkaline reaction (action of the organisms upon protein 
when the utilizable carbohydrate is exhausted).'' 
Enzi/mes. — Dysentery bacilli do not appear to produce extracellular 
proteolytic enzymes. They do not liquefy gelatin, blood serum or 
fibrin, and do not coagulate milk. Wells and ("orper^ have demon- 
strated a lipase of moderate activity in the autolysates of dysentery- 
bacilli. 
To.vins. — {a) Exotoxin.— The nature of the poison produced by 
the Shiga bacillus, the most virulent of the dysentery bacilli, is a 
matter of debate. Todd,** Liidke,^ Doerr^" and Kraus and Doerr" 
state that the organism produces a soluble (exo-) toxin which stimu- 
lates antibody formation in suitable animals; the sera are specifically 
1 British Med. Jour., 1907, ii, 16. 
2 Boston Med. and Surg. Jour., 1911, 164, .301; 1918, 169, 741, 75.3. .Jour. Am. 
Chem. Soc, 1913, 35, 1211. 
3 Les Dysenteries, Paris, 1909, p. 36. * Ztsohr. f. Hyg., 1902, 41, 559. 
'- Boston Jour. Med. Sci., 1897, 2, 236. .Jones: Jour. Infec. Dis., 1914, 15, 357. 
^ See Kendall, Day and W'alker for essential analytical details (Jour. Am. Chem. 
Assn., 1914, 36, 1940;. 
' Jour. Infeo. Dis., 1912, 11, 388. s jour. Hyg., 1904, 4, 480. 
3 .Jour. Pathol, and Bacteriol., 1905, 10, 328. 
" Centralbl. f. Bakteriol., orig., 1905. 38, 420, 511. 
" Ztschr. f. Hyg., 1906, 55, 1. 
