Microbiology Lecture 4.11: Bacillus anthracis

What is the disease caused by Bacillus anthracis?

Anthrax

What is the pathway of anthrax transmission?

Spores --> Germinate in host --> Vegetative cells kill host --> Sporulation --> Spores dispersed back into environment

What is the main transmission method of anthrax?

Zoonotic

What are the three types of anthrax transmission?

1. Inhalation

2. Gastrointestinal

3. Cutaneous

What category of agent is virulent B. anthracis?

CDC Category A Select Agent

Does anthrax spread human to human?

No

Is anthrax a bioweapon?

Yes

95% of human anthrax cases are what type?

Cutaneaous

What do B. anthracis spores enter in humans?

Abrasions, cuts, or insect bites on skin

What forms on the skin after three days post anthrax infection?

Papule

What do the vesicles around the papule ulcerate into?

Coal Black Eschar

What disease forms around the site of anthrax infection?

Edema

Are eschars painful?

No

What happens if anthrax is left untreated?

Sepsis

How is anthrax transmitted gastrointestinally?

Ingesting spore-contaminated meat

What are the abdominal symptoms of gastrointestinal anthrax?

1. Nausea

2. Bloody diarrhea

3. Septicemia

What are the oro-esophageal symptoms of gastrointestinal anthrax?

1. Sore throat

2. Dysphagia

3. Edema

When do symptoms form for inhalation anthrax?

After 2 - 5 days

Are the first symptoms caused by inhalation anthrax specific?

No

What are the symptoms of acute inhalation anthrax?

1. Difficulty breathing

2. Tachycardia

Is inhalation anthrax fatal?

Extremely fatal

What color are B. anthracis?

White

Are B. anthracis hemolytic?

No

Which virulence plasmid in B. anthracis encodes anthrax toxin?

pXO1

Which virulence plasmid in B. anthracis encodes capsule biosynthesis machinery?

pXO2

What are the virulence factors of B. anthracis?

1. Anthrax toxin

2. Gamma-PGA Capsule

What are the anthrax toxins?

1. Protective antigen

2. Lethal factor

3. Edema factor

Are anthrax toxins toxic individually?

No

What are the two possible anthrax toxin combinations?

1. Lethal Toxin (PA + LF)

2. Edema Toxin (PA + EF)

What is required for anthrax toxin action?

Translocation of LF/EF across host membranes

Where are translocon machinery found for anthrax toxins?

PA Oligomer Complex

What needs to happen for LF and EF to traverse the PA pore?

Protein Unfolding

What cleaves PA to release pro-domain?

Furin-like Protease

What do cleaved PA assemble into?

Ring-Shaped Oligomer

What are the steps of host cell intoxication by anthrax toxins?

1. Binding + Endocytosis

2. Acidification + Pore Formation

3. Unfolding + Translocation of LF/EF

What is the catalytic activity of LF?

Proteolytic Cleavage

What is the catalytic activity of EF?

Production of cAMP

What is the main treatment method for anthrax?

Antibiotics

What are the alternative treatments for anthrax?

1. Interfere with anthrax toxin function

2. Anti-toxin humanized monoclonal antibodies

What is the prevention method for anthrax?

Vaccination of animal herds and workers

Is B. anthracis motile and flagellated?

No