Lesson 13: Brucella species

Question 1

• small gram-negative coccobacilli (0.6 x 0.6 to 1.5um)
• stain red using the modified Ziehl-Neelsen method
• Aerobic and capnophilic
• non-motile, catalase positive

Answer 1

Brucella species

Question 2

• most isolates are oxidase-positive
• urease-positive
• intracellular pathogens
• target reproductive organs of certain species of animals
• some species cause undulant fever in humans

Answer 2

Brucella species

Question 3

colonies occur in smooth forms and are small, glistening, bluish and translucent after incubation for 3-5 days. Colonies become opaque with age

Answer 3

B. abortus, B. melitensis, B. suis

Question 4

colonies occur in rough forms. these rough colonies are dull, yellowish, opaque and friable

Answer 4

B. ovis and B. canis

Question 5

are non- haemolytic on blood agar

Answer 5

Brucellae

Question 6

isolates of B. abortus are lysed by a specific bacteriophage at?

Answer 6

Routine test dilution

Question 7

are used to detect the presence of important surface antigen, abortus antigen A and melitensis antigen M

Answer 7

Slide agglutination test with monospecific antisera

Question 8

a feature of the rough brucellae B. ovis and B. canis, can be detected by anti R-serum

Answer 8

R antigen