FAMILY EXTEKOBACTERIACEAi: 535 



Genus II. Shigella Castellani and Chalmers* 



(Castellani and Chalmers, Man. Trop. Med., 3rd ed., 1919, 936; subgenera, Flex- 

 nerella and Shigella, Castellani and Chalmers, ibid., 938; Castellanus Carruti, Jour. 

 Trop. Med. and Hyg., July 15, 1930; Proshigella Borman, Stuart and Wheeler, Jour. 

 Bact., Jt8, 1944, 363.) Xamed for Prof. I. Shiga, the Japanese bacteriologist who dis- 

 covered the dysenterj- bacillus in 1898. 



Non-motile rods, although cultures of some of the less well-known species have been 

 reported as motile. Produce acid but no gas from carbohydrates except with some 

 types of Shigella paradysenteriae. Do not liquefy gelatin. Some species produce 

 acid from lactose and form indole. Some species reduce trimethylamine oxide to 

 trimethylamine, others do not.f Some species will grow at 45.5°C (Eijkman test).t 

 Pathogenic (causing dysenteries) or non-pathogenic species, all living in the bodies 

 of warm-blooded animals. Carried by polluted water supplies and by flies. 



The type species is Shigella dysenteriae (Shiga) Castellani and Chalmers. 



Key to the species of genus Shigella.*'' 



I. Xo acid from mannitol. 



A. Xo acid from lactose. IMilk not coagulated. 



1. Indole not produced. 



a. Acid but no gas from glucose. 



1. Shigella dysenteriae. 

 aa. Acid and a small amount of gas from glucose. 



4a. See Shigella paradysenteriae 

 (Type Xewcastle). 



2. Indole produced. 



2. Shigella ambigua. 



B. Acid formed slowlv from lactose. 

 1. Indole not produced. 



3. Shigella gintottensis. 

 II. Acid from mannitol (one type produces a small amount of gas). 



A. Xo acid from lactose. 



1. Xo acid from rhamnose, .xylose or dulcitol. 



4. Shigella paradysenteriae. 



2. Acid from rhamnose, xylose and dulcitol. 



5. Shigella alkalescens. 



3. .\cid from x.vlosc but not from dulcitol. 



6. Shigella pfaffii. 



B. Acid formed slowly from lactose. 

 1. Indole not produced. 



a. Acid from rhamnose. Xone from .xylose. 



7. Shigella sonnei. 

 aa. Xo acid from rhamnose. Acid from xylose. 



8. Shigella cquirulis. 



* Completely revised by Dr. Frederick Smith, McGill University, Montreal, P. Q., 

 Canada, December, 1938; further revision, April, 1946. 

 t Wood, Baird and Keeping, Jour. Bact., 46, 1943, 106. 

 t Stuart and Rustigian, Jour. Bact., 46, 1943, 105. 

 ** See Weil, Jour. Immunology, 55, 1947, .363-405. 



