FAMILY IV. ENTEROBACTERIACEAE 



389 



dispar (in part) Andrewes, Lancet, 194, 

 1918, 560 (see Shigella dispar); Bacterium 

 sonnei Levine, Jour. Inf. Dis., 27, 1920, 31; 

 Weldin, Iowa State Coll. Jour. Sci., 1, 1927, 

 182; Proshigella sonnei Borman, Stuart and 

 Wheeler, Jour. Bact., 48, 1944, 363.) 



son'ne.i. M.L. gen. noun sonnei of Sonne; 

 named for Dr. Carl Sonne, who worked with 

 this organism. 

 Rods. Non-motile. Gram-negative. 

 Gelatin: No liquefaction. 

 Agar colonies : Cultures dissociate readily, 

 and after the first transfers variants develop 

 which modify their appearance and anti- 

 genic structure. Three, and sometimes even 

 four, colony forms may develop (Wheeler 

 and Mickle, 1951). Phase I colony: circular, 

 gray, convex, 2 to 4 mm in diameter, entire, 

 smooth, glistening; readily emulsified in 

 normal saline. Phase II colony: granular, 

 glistening, 5 mm in diameter, translucent 

 edge, irregular; readily emulsified in normal 

 saline. Goebel et al. describe phase Ilr 

 colonies similar to the phase II colonies of 

 Wheeler and phase lis colonies, small (1 to 

 2 mm in diameter), smooth and glistening, 

 which have a distinctive antigenic struc- 

 ture. The organisms of these colonies emul- 

 sify readily (Baker and Goebel, 1949). The 

 colonies in phase II of Shigella sonnei do not 

 grow on certain selective media, SS agar or 

 desoxycholate agar (Leifson). 



Broth: Many strains make the medium 

 turbid just as do cultures oi Shigella flexneri; 

 some form heavy flakes by spontaneous 

 agglutination of the cells. In broth cultures 

 the variation S -^ R is common. These 

 colonies are flat, 8 to 10 mm in diameter, 

 gray, undulate, rugose with irregular, some- 

 times lobate, edges. Spontaneous agglutina- 

 tion occurs in normal saline. 



Milk: Coagulated in 4 to 30 days. 



Indole not produced. 



Acid but no gas from lactose (2 to 30 days) 

 or sucrose (10 to 40 days) . Acid from glucose, 

 fructose, maltose, galactose, mannitol, 

 arabinose, raffinose and rhamnose in 24 

 hours. Dulcitol, inositol, adonitol and 

 xylose usually not attacked. 



Nitrites produced from nitrates. 



Trimethylamine produced from tri- 

 methylamine oxide. 



Aerobic, facultatively anaerobic. 



Optimum temperature, 37° C. Growth at 

 45.5° C. 



Antigenic structure: Antigens of phase I, 

 extracted in an aqueous solution of glyc- 

 erol, and those of phase lis, extracted in a 

 50 per cent solution of pyridine, are protein 

 lipocarbohydrates of a nearly similar chemi- 

 cal composition. 



The serum prepared with living organisms 

 in phase I agglutinates bacteria in phases I 

 and II, while that prepared with organisms 

 in phase II agglutinates only bacteria in 

 phase II. The agglutination of phase II 

 organisms by the antiserum of phase I is 

 explained by the presence of bacteria under- 

 going phase II mutation. The antiserum pre- 

 pared with the organisms of phase lis agglu- 

 tinates the organisms of phase lis and of 

 phase llr but has no effect on the organisms 

 of phase I. On the contrary, the antigens of 

 phases I and lis are strongly specific 

 (Goebel). Shigella sonnei in phase II has 

 antigenic components common to Shigella 

 boydii 6, Shigella boydii 4, Shigella alkalescens 

 and Shigella dispar. 



Distinctive characters: Appearance of 

 broth cultures and of agar colonies; slow 

 fermentation of lactose. 



Comments : Some strains of Shigella sonnei 

 do not ferment lactose, make milk alkaline 

 or ferment xylose or rhamnose in 24 hours. 

 Other strains which do not attack rhamnose 

 have the same biochemical reactions as 

 Shigella boydii 6 (D 10) . The cells of these 

 colonies in phase I and phase II are agglu- 

 tinated by the anti-sonnei serum absorbed 

 by D 19 (Rubinsten and Pi6chaud, Ann. 

 Inst. Past., 82, 1952, 770). 



Hammarstrom (Lancet, 1, 1947, 102; and 

 Acta med. Scand., ISS, 1949, Suppl. No. 

 223) has classified the strains of Shigella 

 sonnei into 68 types by means of eleven 

 specific bacteriophages and one non-specific 

 bacteriophage tending to show whether the 

 culture is in the typable form, R. Types 3 

 and 5 are the most common, then types 7, 8, 

 12, 16, 53 and 19. This method is of great 

 epidemiological value. 



Source: Isolated from feces in cases of 

 dysenterj' or gastroenteritis; also isolated 

 from drinking water (Green and MacLeod, 

 1943). 



