SF, NB, catalase POSITIVE bacilli

• Bacillus anthracis

  Virulence factors

  • Capsule - Protects the organism from phagocytosis and Polypeptide of the D-glutamic acid
  • Anthrax toxin - consist of three proteins

  1. Protective Antigen (PA) : combined EF and LF. They will be having a cytotoxic and immunomodulating effect
  2. EF : Edema toxin
  3. LF : Lethal toxin
• Clinical infections

  ANTHRAX

  1. Cutaneous Anthrax

  • Do not spread from animal to animal but can be spread from animal feeding on plants contaminated with spores or from contaminated soils
  • Humans are infected by accidental and occupational exposure
  • Occur when wounds are contaminated with anthrax spores acquired through skin cuts, abrasions, or insect bites
• Clinical infections

  ANTHRAX

  2. Inhalation Anthrax

  • Wool-sorter’s disease
  • Acquired when spores are inhaled into the pulmonary parenchyma
• Clinical infections

  ANTHRAX

  3. Gastrointestinal Anthrax

  • Occurs when the spores are inoculated into a lesion on the intestinal mucosa after ingestion of the spores.
• Clinical infections

  ANTHRAX

  4. Injectional Anthrax

  • Characterized by soft tissue infection associated with “skin popping” or other forms of injection drug use and results from the direct injection of the spore into tissue
• Bacillus Anthracis Laboratory Diagnosis

  • Large, square-ended, gram-positive or gram-variable rod found singly or in chains
  • Bamboo rods
  • As the bacteria are subcultures, capsule production ceases
  • Incubation in an atmosphere containing increased CO2 can stimulate capsule production
• Laboratory Diagnosis - Cultural Characteristics

  • Medusa Head
  • Beaten egg whites : Colonies will have a tenacious consistency; hold tightly to the agar surface when the edges are lifted;
  • Able to stand upright without support
  • Round and have a “cut glass” appearance in transmitted light
• Bacillus Cereus

  • Common cause of food poisoning and opportunistic infections in susceptible hosts
  • Grown aerobically at 37°C on SBA
  • B-hemolytic frosted glass – appearing colony
  • Able to ferment salicin, and lecithinase positive
  • Enterotoxin (diarrhea) and emetic toxin (vomiting)
• OTHER BACILLUS SPECIES

  • Bacillus subtilis

  • Bacillus licheniformis

  • Bacillus circulans

  • Bacillus pumilus

  • Bacillus sphaericus