Bacillus anthracis

Bacillus anthracis is a gram-positive, rod-shaped bacterium and the etiological agent of anthrax, a highly lethal disease of humans and animals. It is one of only a few bacteria capable of forming long-lived spores, which allows it to survive in harsh conditions for extended periods.

Characteristics

Bacillus anthracis is a large, non-motile, spore-forming bacterium. It is classified as a gram-positive bacterium due to the thick peptidoglycan layer in its cell wall, which retains the violet crystal violet stain used in the Gram stain procedure.

Pathogenesis

The pathogenicity of Bacillus anthracis is primarily due to two factors: the ability to form spores, and the production of anthrax toxin. The spores allow the bacterium to survive in a dormant state in the soil for many years, and are resistant to heat, cold, radiation, desiccation, and disinfectants. The anthrax toxin is composed of three separate proteins, which work together to disrupt cellular processes and cause cell death.

Infection and Disease

Infection with Bacillus anthracis can occur in three forms: cutaneous, inhalation, and gastrointestinal. Cutaneous anthrax is the most common form and occurs when the bacterium enters a cut or abrasion on the skin. Inhalation anthrax, also known as woolsorter's disease, occurs when spores are inhaled. Gastrointestinal anthrax occurs when spores are ingested.

Treatment and Prevention

Treatment for anthrax involves antibiotics such as ciprofloxacin, doxycycline, or penicillin. Vaccination is available for those at high risk of exposure, such as military personnel, laboratory workers, and individuals who handle potentially infected animals.

See Also

• Anthrax
• Bacillus (genus)
• Gram-positive bacteria
• Spore