- Biosafety Level 2 for processing clinical specimens.
- Biosafety Level 3 practices for all culture manipulations that might produce aerosols.
- Gram-positive rods
- Catalase positive
- Spores present when cultured aerobically without CO2
- Rapidly-growing colonies 2-5 mm overnight at 35C.
- Non-pigmented, dry “ground glass” surface, flat or slightly convex, irregular edges with comma projections (Medusa head).
- Sticky (tenacious) consistency. When teased with loop, will stand up like beaten egg white.
- Colonies are not hemolytic on sheep blood agar.
- Large Gram-positive bacillus, singly and in chains. May become Gram-variable after 72 hours. May be encapsulated in clinical material and blood cultures.
- Terminal/subterminal spores do not swell vegetative cells. Spores may be seen on Gram stain, malachite green stain or by phase contrast microscopy.
- Spores are not present in clinical material unless exposed to low CO2 levels, such as those found in the atmosphere. Higher levels will inhibit sporulation.