Habitat: A cause of dysentery in man; causes diarrhoea in infants and adults. 8. Shigella dispar (Andrewes, 1918) Bergey et al., 1930. {Bacilhis ceylanensis B (sic), Castellani, Jour. Hyg., 7, 1907, 9; Bacillus dispar (in part) Andrewes, Lancet, 194^, 1918, 560 (see Shigella sonnei; Andrewes included in Bacillus dispar all lactose-fer- menting members of the dysentery group) ; Castellanus castellanii Cerruti, Jour. Trop. Med. and Hyg., 33, 1930, 207; Bergey et al., Manual, 3rd ed., 1930, 364; Proshigella dispar Borman, Stuart and Wheeler, Jour. Bact., 48, 1944, 363.) dis'par. L. adj. dispar unlike. Rods. Non-motile. Gram-negative. Culturally resembles Shigella sonnei Weldin. Gelatin: No liquefaction. Milk is sometimes slowly coagulated. Indole is produced. Hydrogen sulfide not produced. Acid from xylose and occasionall}' from lactose and dulcitol. Nitrites produced from nitrates. Trimethylamine produced from tri- methylamine o.xide. Antigenic structure : The antigens of this species mtiy be identical with those of Shigella boydii 5, Shigella flexneri 6 and cer- tain strains of Escherichia coli. Dissociation: The S colonies do not dis- sociate into phase II but change rather rapidly into S ^ R variants. Relationships to other species: Culturally resembles Shigella sonnei Weldin but differs from the latter biochemically and serologi- cally. Kauffman and Frantzen combine Shigella alkalescens and S. dispar, placing them in a group they call the "Alkalescens-Dispar Group." This was done to include these two organisms in the Escherichia coli anaerogenes group because they have O and K antigens similar to those found in the genus Es- cherichia. O agglutination may be masked by the K antigen or by a capsular A antigen. Frantzen described eight biochemical and serological groups of Alkalescens-Dispar. The diagnosis of the groups is determined by the agglutination of a boiled emulsion with one of the eight specific sera. The O antigens of these eight groups have fractions similar to the somatic antigens of certain varieties of Escherichia coli. Oftentimes the biochemical and serological characters show no relationship, except in the case oi Shigella alkalescens Type 1, which has stable bio- chemical characters. Source : Isolated from the feces and intes- tines of persons suffering from dysentery. Habitat: Most frequently found in the urine of persons having cystitis, pyelitis or pyelonephritis, in the blood of persons ill with septicemia and in the feces of dysen- tery patients or of healthy individuals. Pathogenic for the urinary tract ; very rarely causes dysentery.
