3F - Anthrax Flashcards
Bacillus anthracis
bacteria that causes anthrax
◦ It is a gram positive, rod shaped bacillus aerobic, non-motile and spore forming
◦ The agent is in the vegetative state (actively growing) in animals
◦ Endospores are formed when environmental conditions are unfavorable, and nutrients are limiting.
spread of endospores
◦ Animals usually ingest the endospores from the environment.
‣ The endospores then germinate into the vegetative form. Animals that die of anthrax tend to bloat and putrefy very rapidly
capsule and the exotoxin produced by B. Anthracis
virulence determinants that are plasmid mediated
◦ Capsule is important is establishing the infection (invasion and evasion of the immune system) and resists both innate responses such as complement and phagocytosis and adaptive immune responses
Three components of the Anthrax exotoxin are required to cause damage to host cells
◦ Protective factor facilitates entry into cell
◦ Edema factor
◦Lethal factor
Edema factor
disrupts cell membrane and electrolyte transport systems → swelling of cells → cell rupture.
Lethal factor
Kills macrophages and endothelial cells of capillaries
‣ (Ingestion) → Injury to the intestinal mucosa → absorption of the anthrax and exotoxin.
• Gut damage → absorption of gram –ve bacteria and endotoxin from the gut
‣ (Into blood vessels) Damage to capillary cell walls and DIC( clotting events, all clotting factors used → hemorrhage) → edema, shock and death
Characteristic necropsy findings associated with anthrax
◦ Sudden death. Seem ok at the morning milking but are dead in the afternoon.
◦ Location – certain areas seem to be associated with anthrax
‣ (In USA- west of the Mississippi- the Plains states, most frequently in the Dakotas)
◦ Rapid bloating of carcasses and putrefaction
◦ Blood from nose, mouth, eyes and anus
‣ This blood from the body orifices does not clot and is jammed packed with the bacteria- making a perfect sample to identify the characteristic bacterial morphology
Anthrax is an important zoonosis
◦ Cutaneous lesion- secondary to contact with infected animals or carcasses but also occurs following contact with infected hides, wool and fur.
◦ Inhalation → pneumonia (Goats skin drums)
◦ Ingestion- may happen following ingestion of meat from animals that died of anthrax
◦ Bacillus anthracis spores have been used as a biological weapon
‣ History of anthrax in the USA
Bacillus anthracis
bacteria that causes anthrax
◦ It is a gram positive, rod shaped bacillus aerobic, non-motile and spore forming
◦ The agent is in the vegetative state (actively growing) in animals
◦ Endospores are formed when environmental conditions are unfavorable, and nutrients are limiting.
spread of endospores
◦ Animals usually ingest the endospores from the environment.
‣ The endospores then germinate into the vegetative form. Animals that die of anthrax tend to bloat and putrefy very rapidly
capsule and the exotoxin produced by B. Anthracis
virulence determinants that are plasmid mediated
◦ Capsule is important is establishing the infection (invasion and evasion of the immune system) and resists both innate responses such as complement and phagocytosis and adaptive immune responses
Three components of the Anthrax exotoxin are required to cause damage to host cells
◦ Protective factor facilitates entry into cell
◦ Edema factor
◦Lethal factor
Edema factor
disrupts cell membrane and electrolyte transport systems → swelling of cells → cell rupture.
Lethal factor
Kills macrophages and endothelial cells of capillaries
‣ (Ingestion) → Injury to the intestinal mucosa → absorption of the anthrax and exotoxin.
• Gut damage → absorption of gram –ve bacteria and endotoxin from the gut
‣ (Into blood vessels) Damage to capillary cell walls and DIC( clotting events, all clotting factors used → hemorrhage) → edema, shock and death
Characteristic necropsy findings associated with anthrax
◦ Sudden death. Seem ok at the morning milking but are dead in the afternoon.
◦ Location – certain areas seem to be associated with anthrax
‣ (In USA- west of the Mississippi- the Plains states, most frequently in the Dakotas)
◦ Rapid bloating of carcasses and putrefaction
◦ Blood from nose, mouth, eyes and anus
‣ This blood from the body orifices does not clot and is jammed packed with the bacteria- making a perfect sample to identify the characteristic bacterial morphology
