granular or beaten-copper surface; differ- entiated into a raised, more opaque center and a flat, clearer periphery with radial striation. Agar slant: After 48 hours at 37° C, growth moderate, confluent, raised, grayish yellow, translucent, with glistening, wavy or beaten-copper surface and an irregularly lobate edge. Blood agar plate: Good growth. No he- molysis. Broth: After 24 hours at 37° C, moderate growth with moderate turbidity which later clears. Viscous sediment. Incomplete surface and ring growth. Becomes alkaline more rapidly than does Pasteur ella pestis. ^ Litmus milk: Usually slightly alkaline. Potato: After 7 days at 22° C, a thin, yellowish membrane appears which later turns brown. Indole not produced. Hydrogen sulfide produced. Acid but no gas from glucose, maltose, arabinose, xylose, rhamnose, salicin, glyc- erol and mannitol. Sometimes acid from sucrose. Methyl red test positive. Acetylmethylcarbinol not produced. Nitrites produced from nitrates. Ammonia is produced. Methylene blue is reduced. Catalase-positive. Aerobic, facultatively anaerobic. Temperature relations: Optimum, 30° C. Minimum, 5° C. Maximum, 43° C. Thermal death point, 60° C. for 10 minutes. Pathogenicity: Infectious for mice, rats, dogs, cats and horses. Distinctive characters: Motile with peri- trichous flagella and H antigen at 22° C; non-motile, non-flagellated and no H antigen at 37° C; this change occurs near 30° C; non-motile strains grown at 37° C. develop flagella when grown at 22° C. (Preston and Maitland, Jour. Gen. Micro- biol., 7, 1952, 117). Comments: See description of Pasturella pestis for comments regarding the difTer- entiation of these two species. Source: Isolated from a guinea pig inocu- lated with material from a horse suspected of having glanders. Habitat: Schiitze (Syst. of Bact. in Relation to Med., Med. Res. Counc, Lon- don, 4, 1929, 474) states that this species appears to be widely distributed in nature, having been found in soil, dust, water, fodder and milk. It causes pseudotuberculosis in the following animals: horse, cow, goat, rabbit, hare, guinea pig, mouse, wild rat, cat, dog, monkey, hen, turkey, pigeon and canary. The organism has been isolated from human blood, spleen, liver, gall blad- der, appendix and cerebro-spinal fluid. 8. Pasteurella tularensis (McCoy and Chapin, 1912) Bergey et al., 1923. (Bac- terium tularense McCoy and Chapin, Jour. Inf. Dis., 10, 1912a, 61; McCoy and Chapin, Public Health Bull. 53, U. S. Treas. Dept., Public Health Service, 1912b, 17; Bergey et al.. Manual, 1st ed., 1923, 267.) tu.la.ren'sis. M.L. adj. tularensis per- taining to Tulare County; named for Tulare, the county in California in which tularemia was first observed. Description taken from McCoy and Chapin (op. cit., 1912a, 61, and op. cit., 1912b, 17) and from Francis (U. S. Hygienic Lab. Bull. 130, 1922). Further revision by Francis, 1947. Equal numbers of cocci and rods; 0.2 by 0.2 to 0.7 micron, occurring singly. Ex- tremely pleomorphic (Hesselbrock and Foshay, Jour. Bact., 49, 1945, 209). Capsules rare or absent. Non-motile. May show bi- polar staining. Gram-negative. No growth on plain agar or in liquid media without special enrichment (Tamura and Gibby, Jour. Bact., 45, 1943, 361). Filtera- ble through Berkefeld filters. Growth occurs on coagulated egg yolk (McCoy and Chapin), on blood glucose cystine agar (Francis), on blood agar, glucose blood agar and glucose serum agar. The addition of fresh, sterile rabbit spleen to the surfaces of the last three media favors the growth of the organism. Forms minute, viscous colonies after 2 to 5 days which may attain a diameter of 4 mm if well separated. Growth readily emulsifiable. Growth on blood media is gray. May cause green discoloration of the blood. Rough, smooth and mucoid variants have not been reported.
