Anthrax and plague Flashcards
devastating disease of livestock?
anthrax
what organism causes anthrax?
bacillus anthracis
bacillus anthracis vs bacillus cereus?
anthracis –> anthrax cereus –> food poisoning
bacillus vs clostridia
both are gram + spore forming rods but bacillus are aerobic or facultatively anaerobic and clostridia are strict anaerobes
bacillus anthracis
gram + rods forming long filaments
“box car” organisms
virulence factors of bacillus anthracis
capsule of poly D-glutamic acid
and
toxins = edema toxin (EF + PA) and lethal toxin (LF + PA)
what is PA?
protective antigen
it is the B subunit (cell-binding component) for both toxins of anthrax
–translocates EF and LF into the cell
***none of the 3 components is toxic on its own
how does anti-PA antiboody work?
it neutralizes both toxins of anthrax because PA is the B subunit (cell binding component) of both toxins
EF
edema fector
a calmodulin-dependent bacterial adenylate cyclase
LF
lethal factor
a zinc metalloprotease that cleaves mitogen-activated protein kinase kinase (MAPKK) and inhibits the MAPK signal transduction pathway in macrophages
reservoir and transmission of bacillus anthracis
- Reservoir: Soil –> Herbivores infected during grazing
- Transmission to humans
—–Contact with infected animals, hides, hair, wool, bone, bone products; biting flies
—–Ingestion of contaminated meat
—–Inhalation-industrial settings, intentional use
3 forms of anthrax
cutaneous
GI
inhalational (woolsorters disease and bioterrorism)
cutaneous anthrax
malignant pustule/most common form
- Occupational exposure to animals/heroin users
- Papule progresses to central necrosis to black eschar
–Painless
–Edema
–80-90% complete resolution
GI anthrax
- RARE
- Follows ingestion of spore-contaminated meat
- Ulcers form at site of invasion (e.g., mouth, esophagus, intestine) which leads to regional lymphadenopathy, edema, and sepsis
- Mortality greater than 50%
inhalational anthrax
- Incubation period 1-43 days (dose dependent)
- Non-specific symptoms 3-5 days
- Terminal phase
–Dyspnea, stridor, cyanosis, increased chest pain, chest wall edema, followed by shock and death within 24-36 hours (45-90%mortality)
–Hemorrhagic mediastinitis, hemorrhagic pleural effusions
•can present with Meningitis and/or GI hemorrhage
what do you see on xray of inhalatinal anthrax?
gram stain of blood?
- Chest x-ray is often pathognomonic: widened mediastinum with pleural effusions, without infiltrates.
- Late in the course, Gram stain of blood may reveal broad Gram-positive rods.
bacillus anthracis
treatment for inhalational and cutaneous anthrax
ciprifloxacin or doxycycline
+
clindamycin
+
rifampin
anthrax vaccine (biothrax)
inactivated vaccine of attenuated, non-encapsulated strain primarily of PA with traces of LF and EF
agent that causes the bubonic plague?
yersinia pestis
description of yersinia pestis?
transmission?
gram - rod; grows well on macconkeys agar
flea vector required for transmission (exception: pneumonic plague)
occurs naturally in the western US/southwestern states, cycling amongst rodents
plague in humans
humans and domestic animals are bitten by fleas from dead animals are at risk for contracting plague
cats can directly infect humans by coughing infectious droplets into the air
dogs less likely to be ill but can still bring home the fleas
in addition to flea bites, people can be exposed by handling skins or flesh of infected animals
plague due to yersinia pestis
pathogenesis and progression
mechanism for anthrax toxin
