Brucella species are highly infectious. Once this organism is suspected
on the basis of clinical and/or laboratory information, additional testing
MUST be performed within a certified biosafety cabinet.
- Biosafety Level 2 for processing clinical specimens.
- Biosafety Level 3 practices for all culture manipulations that
might produce aerosols.
- Gram-negative, coccobacillus
- Grows slowly at 35-37C. CO2 enhances growth of some biovars of
- Catalase positive
- Oxidase positive (B. canis is variable)
- Urease positive; strong, typically <2h, some within 5 minutes.
- X and V factors are not required.
- Usually not visible or pinpoint at 24 hrs.
- Grows slowly on most standard laboratory media (ie. sheep blood,
chocolate and tryptic soy agars). Pinpoint, smooth, with an entire
border, translucent, non-hemolytic at 48 hrs.
- Some strains grow on MacConkey agar.
- Grows on Martin-Lewis and Thayer-Martin agars.
Faintly-staining, small Gram-negative coccobacillus (0.5-0.7 x 0.6-1.5
µm), seen mostly as single cells and appearing like “fine sand”.
Bipolar staining is not a distinctive feature. Although a small Gram-negative
coccobacillus, cells are typically larger than those of F. tularensis