832 BRUCELLA ABORTUS 



Resistance. — Not specially resistant. Killed by moist heat at 60° C. in 10 minutes, and 

 by I'O per cent, phenol in about 15 minutes. In the dried, powdered condition 

 they may survive for 3 months. Sealed agar slope cultures at room temperature 

 may remain aUve for 1-6 months. 



Metabolism. — Aerobic ; no growth under strictly anaerobic conditions. Growth is often 

 improved by 10 per cent. COj. Opt. temp. 37° C. ; limits 20-40° C. Opt. H-ion 

 concentration pH 6-6-7-4. Growth slightly improved by glucose, glycerine, liver 

 extract, blood and serum. Brown pigment formed on potato and sometimes in 

 old agar cultures. Broth turned alkaUne — to pH 8 or even higher. Growth in 

 all media is relatively slow. Some growth on MacConkey's medium. Does not 

 hsemolyse blood. 



Biochemical. — No carbohydrates fermented. L.M. turned shghtly alkaline. Indole — ; 

 M.R. — ; V.P. — ; Nitrates and nitrites reduced. NH3 sometimes -\- ; HgS — ; 

 M.B. reduced; catalase-j-. 



Antigenic Structure. — Only one serological type known. Appears to contain the same 

 antigens as Br. abortus and Br. siiis, but in different quantitative proportions. 

 Provided absolutely smooth strains are used, it may be differentiated from Br. 

 abortus and Br. suis by quantitative absorption of agglutinins. The rough variant, 

 incorrectly called Br. "paramelitensis, is agglutinable by non-specific agents, but not 

 by a serum prepared against the smooth form. 



Pathogenicity.- — Causes undulant fever in man, and a septicsemic infection of goats and 

 sheep, sometimes accompanied by abortion. May infect cows and be excreted in 

 the milk. Experimentally, it is pathogenic to a variable degree for man, goats, 

 sheep, monkeys, and the small laboratory animals. The rough variant is avirulent. 



Brucella abortus 



Isolation. — By Bang (1897) from cows with infectious abortion. 



Habitat. — Strict parasite, occurring in cattle, horses, dogs, and man. 



Morphology. — Similar to that of type species, but usually more bacillary ; rods reach 

 1-6 ^i in length, or on special media even 30 /n. May be capsulated. 



Cultural Characters.- — Similar to those of type species, except that growth of the bovine 

 type, whether isolated from cattle or from man, usually occurs only in the presence 

 of added COg, preferably 5-10 per cent. In shake agar cultures growth occurs 1-2 

 mm. or more below the surface, and extends downwards for ^-1 cm. Old laboratory 

 cultures grow freely under aerobic conditions ; no growth under strictly anaerobic 

 conditions. 



Resistance. — Similar to type species. In uterine exudate kept in the ice- chest it survives 

 for 9 months. May live in sterile water for 3 or 4 months. Readily killed in milk 

 by holder pasteurization. May survive in ice-cream for a month. 



Metabolism. — Similar to type species, but as most strains on isolation require COj, the 

 optimum H-ion concentration of media is about pH 6-6. Brown coloration in old 

 agar cultures less common than with Br. melitensis. 



Biochemical. — Similar to type species, but nearly all strains on isolation produce HgS in 

 liver agar for at least 4 days. 



Antigenic Structure. — Appears to possess the same antigens as Br. melitensis, but distributed 

 in different quantitative proportions. Provided absolutely smooth strains are 

 used, it may be differentiated from Br. melitensis by quantitative absorption of 

 agglutinins. The rough variant, incorrectly referred to as Br. para-abortus, is 

 agglutinable by non-specific agents. 



Pathogenicity. — Causes epizootic abortion in cattle, fist ulous withers in horses, and a mild 

 septicsemic infection in dogs. Is said to infect rats. Gives rise to undulant fever 

 in man. Experimentally, it is pathogenic to a variable degree for man, cattle, 

 horses, dogs, fowls, monkeys, and the small laboratory animals. The rough 

 variant is avirulent. 



