Genus III. Brucella Meyer and Shaw, 1920* (Jour. Inf. Dis., 27, 1920, 173.) Bru.cel'la. L. dim. ending -ella; M.L. fem.n. Brucella named for Sir David Bruce, who first recognized the organism causing undulant fever. Short, rod-shaped to coccoid cells, 0.5 by 0.5 to 2.0 microns. Encapsulated. Non-motile. Gram-negative. Gelatin is not liquefied. No gas produced from carbohydrates. Urea is hy- drolyzed. Parasitic, invading all animal tissues and producing infection of the genital organs, the mammary gland and the respiratory and intestinal tracts. Pathogenic for vari- ous species of domestic animals and man. It has been found that a measurement of urease activity of the cells cannot be used as a means of differentiating the species in Brucella (Sanders and Warner, Jour. Bact., 62, 1951, 591). The differentiation of the species of Brucella by the bacteriostatic action of dyes depends upon the medium used. When tryptose agar (Difco) is used, basic fuchsin and thionin should be used in a final dilution of 1:100,000. There are several forms of the R and mucoid types of Brucella spp. (Huddleson, Mich. Agr. Exp. Sta. Mem. 6, 1952). The true R type differs from the S type in its lack of patho- genicity, its antigenic properties, its susceptibility to agglutination by exposure of suspen- sions to heat and to acriflavine in concentration of 1:2000 and in its colonial appearance. The mucoid types differ antigenically, morphologically and culturally. Colonies on agar are spherical or flat, regular in contour, grayish to reddish yellow in appearance. Suspen- sions are agglutinated by heat and acriflavine; they are not always agglutinated by special agglutinating sera. There is no change in their growth characteristics on media containing either basic fuchsin or thionin. For recent literature concerning this group of organisms, see Hoyer (Brucellosis, Amer Assoc. Adv. Sci., Washington, 1950, 9), Pacheco and Thiago de Mello (Jour. Bact., 59, 1950 689), Sanders and Huddleson (Amer. Jour. Vet. Res., 11, 1950, 75), Polding (Indian Vet Jour., 27, 1950, 170), Marr and Wilson (Proc. Soc. Exp. Biol, and Med., 75, 1950, 438), San ders and Warner (Jour. Bact., 62, 1951, 591), White and Wilson (Jour. Bact., 61, 1951, 239)^ Huddleson (Mich. Agr. Exp. Sta. Mem. 5, 1952, 67 pp.), Renoux (Ann. Inst. Past., 82 1952, 1), Pickett, Nelson and Liberman (Jour. Bact., 66, 1953, 210), Cruickshank (Jour Hyg., 52, 1954, 105) and Pickett and Nelson (Jour. Bact., 69, 1955, 333). For literature dis cussing a wasting disease of chickens caused by these organisms, see Dubois (Rev. Vet., 67 1910, 490), Huddleson and Emmel (Mich. State Coll. Agr. Exp. Sta., Tech. Bull. 103, 1929) Gillman and Brunett (Cornell Vet., 20, 1930, 371) and Wilson (Jour. Hyg., 4, 1933, 516). The type species is Brucella melitensis (Hughes) Meyer and Shaw. Key to the species of genus Brucella. I. Grow in special media containing basic fuchsin. A. Grows in media containing thionin. 1. Brucella melitensis. B. Does not grow in media containing thionin. 2. Brucella abortus. II. Does not grow in media containing basic fuchsin; grows in media containing thionin. 3. Brucella suis.
- Revised by Prof. I. F. Huddleson, Michigan State College, East Lansing, Michigan,
December, 1942; further revision, May, 1955.
