FAMILY IV. ENTEROBACTERIACEAE 



385 



Determ. Bact., 1901, 228; Castellani and 

 Chalmers, Man. Trop. Med., 3rd ed., 1919, 

 935.) 



dy.sen.te'ri.ae. Gr. noun dysenteria 

 d^'senter}-; ^NI.L. gen. noun dysenteriae of 

 dysentery. 



Rods, 0.4 to 0.6 by 1.0 to 3.0 microns, oc- 

 curring singly. Non-motile. Gram-negative. 



Gelatin: Surface growth. No liquefaction. 



Agar colonies: Circular, 1.0 to 1.5 mm in 

 diameter, raised, gray, opaque, shiny, en- 

 tire. After 48 hours there is spreading, and 

 the centers of the colonies become thick- 

 ened. 



Broth : Slightly turbid in several hours, in- 

 creasing after 18 hours to a homogeneous 

 turbidity. 



Litmus milk: Slightly acid, slowly becom- 

 ing slightlj^ alkaline. 



Potato: Growth shinj^ slowly turning 

 brown. 



Indole not produced. 



Hydrogen sulfide not produced. 



Acid but no gas from glucose, fructose, 

 galactose, rafhnose and sometimes from 

 glycerol (positive reaction with Stern's 

 medium). Xylose, maltose, sucrose, manni- 

 tol, dulcitol, arabinose, rhamnose, salicin 

 and adonitol not attacked. 



Kligler's medium: Red slope; yellow butt; 

 no gas. 



Nitrites produced from nitrates. 



Trimethylamine not produced from tri- 

 methylamine oxide. 



Catalase not produced. 



Aerobic, facultatively anaerobic. 



Optimum temperature, 37° C. No growth 

 at 45° C. 



Antigenic structure: The antigen of 

 Shigella dysenteriae consists of a non-anti- 

 genic phospholipid and an antigenic toxic 

 protein together with a polj'saccharide re- 

 sponsible for the serological reactions 

 (Boivin and Mesrobeanu, 1937; Morgan and 

 Patridge, 1940) . All strains have an identical 

 antigenic structure; they also have a minor 

 antigen, identical with that of Shigella 

 ambigua Weldin, which does not interfere 

 with slide agglutination. 



Toxin production: Among the dysentery 

 bacilli only Shigella dysenteriae produces an 

 active exotoxin in liquid media which can 

 be changed into an anatoxin (toxoid) by the 



action of formalin and heat (Ramon, Dumas 

 and Said Bilal, 1926). 



Pathogenicity: Avirulent but toxic for 

 man causing epidemic bacillary dysentery. 

 This is the only dysentery bacillus patho- 

 genic for laboratory animals (rabbits, mice, 

 monkeys and dogs), producing lesions simi- 

 lar to those found in man. 



Dissociation: Dissociates spontaneously 

 into S and R variants. The latter, which lack 

 the antigen, can produce an active exo- 

 toxin. 



Source: Isolated from widespread epi- 

 demics of dysentery. 



Habitat : A cause of dysentery in man and 

 monkeys. Found only in feces of the sick. 



2. Shigella schinitzii (Weldin and 

 Levine, 1923) Hauduroy et al., 1937. {Shi- 

 gella parashigae Remlinger and Dumas, Ann. 

 Inst. Past., 29, 1915, 493; Bazillus Schmitz, 

 Schmitz, Ztschr. f. Hyg., 84, 1917, 449; 

 Bacillus dysenteriae "Schmitz", Murray, 

 Jour. Roy. Army Med. Corps, 31, 1918, 257; 

 Bacillus ambiguus Andrewes, Lancet, 194, 

 1918, 560; Bacterium schmitzii Weldin and 

 Levine, Abst. Bact., 7, 1923, 13; Shigella 

 ambigua Weldin, Iowa State College Jour. 

 Sci., 1, 1927, 177; Hauduroy et al.. Diet. d. 

 Bact. Path., 1937, 496.) 



schmit'zi.i. M.L. gen. noun schmitzii of 

 Schmitz; named for Dr. K. E. F. Schmitz of 

 Roumania. 



Morphology and cultural characters on 

 agar, gelatin, broth, milk and potato are 

 identical with those of Shigella dysenteriae. 



Indole always produced. 



Hj^drogen sulfide not produced. 



Acid from glucose, galactose, fructose, 

 maltose and rhamnose; irregular acid pro- 

 duction within 4 days from arabinose. No 

 acid from lactose, sucrose, mannitol, dul- 

 citol, sorbitol, salicin, xylose or glycerol 

 (negative reaction with Stern's medium). 



Nitrites not produced from nitrates. 



Trimethylamine not produced from tri- 

 methylamine oxide. 



Catalase not produced. 



Aerobic, facultativeh^ anaerobic. 



Temperature relations: Optimum, 37° C. 

 No growth at 45° C. 



Antigenic character: Possesses a major 

 antigen specific to this species only and a 



