Lecture 11 Anthrax Flashcards
What are some traits of Bacillus Anthracis?
- Aerobic
- Gram positive
- rod/ Long shape
- thin
What are the 2 forms of anthracis?
- spores
2. vegetative state
What are the steps spore formation of anthracis?
- Inert spores formed upon exposure to O2
- Infectious form, hardy
- Approximately 1µm in size
- The spores do not divide; have no measurable metabolism
What are the the steps of the vegetative state of anthracis?
- Once ingested, spores get taken up by macrophages and carried to the lymph nodes.
- The spores begin to germinate and enter the vegetative state in the macrophages, eventually lysing them, and overwhelming the lymph node.
- The infection then enters the blood stream.
How are anthracis spread from animals to humans?
- Animals in the late stages of infection bleed through the nose, mouth, and bowel.
- The blood exposes the surrounding soil to the vegetative bacteria, as does the corpse of the infected animal when it dies.
- Exposure to O2 at this stage stimulates formation of spores which stay stored in the soil for repeat of the bacterial life cycle.
What are the environmental survival characteristics of spores?
spores are hardy, and soil is favorable for spore viability
What factors of the soil make it viable for spore formation?
- High moisture
- Organic content
- Alkaline pH
- High calcium concentration
What factors of the spores help the survive?
- Resistant to drying, boiling <10 minutes, ultraviolet light, and even gamma radiation
- Survive for years in soil (natural reservoir)
- Still viable for decades in permafrost
What are the 3 mechanisms of transmission of anthrax?
- cutaneous
- GI
- Inhalation
How can anthrax be inhaled?
- Handling hides/skins of infected animals
- Microbiology laboratory
- Intentional aerosol release
- Small volume powdered form
How can anthrax be cutenously transmitted?
- Handling hides/skins of infected animals
- Bites from arthropods (very rare)
- Handling powdered form in letters, etc.
- Intentional aerosol release
How can anthrax be transmitted intestinally?
- Ingestion of meat from infected animal
- Ingestion of contaminated food and water
- Ingestion from powder-contaminated hands
What are the 3 stages of inhalation infection?
- Asymptomatic incubation period; 2-43 days
- Prodromal (Early) phase; several hours-3 days
- Fulminant Phase
What are the symptoms of the prodromal phase of inhalation?
Nonspecific flu-like symptoms: Fever, malaise, myalgias (muscle pain)
Labored breathing, nonproductive cough, mild chest discomfort
What are the symptoms of the prodromal phase of inhalation?
Critically ill: Fever, high level of perspiration
Respiratory distress/failure, cyanosis (bluish discoloration of skin due to poor circulation or insufficient oxygen levels)
Septic shock, multiorgan failure, DIC
50% develop hemorrhagic meningitis - Headache, delirium, coma
Usually progresses to death in <36 hrs
What is the fulminat phase correlated with?
Correlates with high-grade bacteremia/toxemia
What is the Prodromal phase correlated with?
Correlates with germination, toxin production
What are the most common areas of cutaneous exposure?
Hands/arms
Neck/head
What is the progression of lesions in cutaneous transmission?
- Papule – Severe itching
- Vesicle/bulla - fluid-filled sacs or lesions
- Ulcer – contains organisms, significant edema and ascites
- Eschar (scab formation_ - black, rarely scars
What systemic disease may develop from cutaneous anthrax?
- Lymphangitis (infection of the lymph vessels)
- sepsis
- death
What are the oropharyngeal symptoms of GI anthrax?
- Regional lymphadenopathy (swelling of lymph nodes)
- Edema, ascites (fluid accumulation in peritoneal cavity)
- Sepsis
What are the early abdominal symptoms?
nausea, vomiting, malaise
What are the late abdominal symptoms?
Blood in stool, acute abdomen, ascites
What is the prognosis of inhalation?
86-100% (despite treatment)
What is the prognosis of cutaneous?
<5% (treated) – 20% (untreated)
What is the prognosis of GI?
25-60%, depending on how early treatment is given
What is the pathogenicity of anthrax?
Disease requires entry of spores into body
Why does exposure to anthrax not always cause disease?
- Inoculation dose
- Route of entry
- Host immune status
- May depend on pathogen strain characteristics
What are the virulence factors of anthra?
- lethal toxin
- edema toxin
- poly-d-glutamic acid capsule
- hemolytic enzyms
- proteases
- BsIA and adhesion
- NOS
What does lethal toxin virulence do?
Interferes with host protective mechanisms and immunity
What does edema toxin virulence do?
Impairs host defense to infection; tissue lesions, multi-organ failure
What does poly-d-glutamic acid capsule virulence do?
inhibits host defense through inhibition of phagocytosis of vegetative cells by macrophages
What does antibiotic treat in anthrax?
Antibiotics are effective against germinating or vegetative B. anthracis but not against the spore form
What are the 2 ineffective antibiotics?
- Trimethoprim/Sulfamethoxazole
2. Third generation cephalosporins
What are the some prevention measures taken for anthrax?
- vaccine
2. adjuvants
What is an adjuvant?
a substance that enhances the body’s immune response to an antigen; can be inorganic or organic substance
What is the efficiency of vaccination in humans?
> 90% cutaneous in humans
What are the local reaction to anthrax vaccine?
Erythema, edema
What are the systemic reactions to anthrax vaccine?
Fever, malaise
which form of anthrax would least likely infect on a large scale?
Gastrointestinal because the acidity in the stomach is too strong for the spores
which type of anthrax is associated with woolsorters disease?
inhalation
what is an adjuvant?
a substance that enhances the body’s immune response to an antigen; can be inorganic or organic substance
