Brucella species
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.Safety:
- Biosafety Level 2 for processing clinical specimens.
- Biosafety Level 3 practices for all culture manipulations that might produce aerosols.
Key Characteristics
- Gram-negative, coccobacillus
- Grows slowly at 35-37C. CO2 enhances growth of some biovars of B. abortus.
- Catalase positive
- Non-motile
- Oxidase positive (B. canis is variable)
- Urease positive; strong, typically <2h, some within 5 minutes.
- X and V factors are not required.
Colony Characteristics:
- 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.
Microscopic Characteristics:
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.Resource
