Lecture 11 Flashcards
what are some traits of bacillus anthracis?
aerobic, gram positive, long and thin
what are the 2 forms of anthracis?
spores and vegetative state
what are some characteristics of spores?
- formed upon exposure to O2
- infectious form and hardy
- dont divide, no measurable metabolism
how does the vegetative state happen?
- spores taken up by macrophages and taken to lymph nodes
2. spores germinate and enter the vegetative state
once anthracis enters the vegetative state, whats next in infection?
- while in macrophages, spores lyse through and overwhelm lymph node
- infection gets in bloodstream
- in late stages animals bleed through nose, mouth, and bowel
- blood and corpse of animal exposed to more O2 creates more spores for cycle to repeat
what traits make spores hardy?
- resistant to drying, boiling less than 10 minutes, UV light and gamma radiation
- survive in soil for years
- still viable for decades in permafrost
what factors make soil favorable for spores?
- high moisture
- organic content
- alkaline (basic) pH
- high calcium concentration
what are the three kinds of anthrax?
cutaneous, gastrointestinal, and inhalational
how is inhalational anthrax transmitted?
- handling hides/skin of infected animals
- microbio lab
- intentional aerosol release
- small volume powdered form
how is cutaenous anthrax transmitted?
- handling hides/skins of infected animals
- bites from bugs
- handling powdered form
- aerosol release
how is gastrointestinal anthrax transmitted?
- ingestion of meat from infected animal
- ingestion of contaminated food
- ingestion from powder contaminated hands
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
what are the three phases of inhalational anthrax and how long does each last?
- asymptomatic period (2-43 days)
- prodromal phase (hours-about 3 days)
- fulminant phase (about 3 days)
what are some traits of prodromal phase?
- correlates with germination and toxin production
- nonspecific flu like symptoms
- lasts several hours to days
- can have transient resolution before next phase
what are some traits of fulminant phase?
- correlates with high grade bacteremia/toxemia
- critically ill
- 50% develop hemorrhagic meningitis
- usually progresses to death
what are the most common areas of exposure for cutaneous anthrax?
hands, arms, neck, head
what is the incubation period for cutaneous anthrax?
normally 3-5 days and 12 days max
True or false: the lesions from cutaneous anthrax are painful
FALSE!!!! they are painless
what is the progression of lesions of cutaneous anthrax?
- papule (severe itching)
- vesicle/bulla (fluid filled)
- ulcer (contains organisms and significant edema)
- eschar (black scab)
can cutaneous anthrax be systemic?
Yes, infected can get lymphangitis (infection of lymph vessels) and if untreated can get to sepsis and death
what are the two types of gastrointestinal anthrax?
oropharyngeal and abdominal
what are some symptoms of oropharyngeal GI anthrax?
oral or esophageal ulcer, regional lymphadenopathy (swelling of lymph nodes), edema, ascites, and sepsis
what are some symptoms of abdominal GI anthrax?
early symptoms are nausea, vomiting, malaise and late symptoms are blood in stool, acute abdomen, ascites
which type of anthrax is associated with woolsorters disease?
inhalational
what are some historical risk factors for humans when it comes to anthrax?
- exposure to livestock
- exposure to wool and hides
- rarely but lab acquired
does exposure to spores always cause disease?
NO!!! it depends on the:
- inoculation dose
- route of entry
- immune status
- characteristics of the pathogen strain
which state of anthrax is the virulent phase?
the vegetative bacillus
what are the three major virulence factors of anthrax?
- lethal toxin
- edema toxin
- poly d-glutamic acid capsule
besides the three major virulence factors what are some other factors?
- hemolytic enzymes
- proteases
- BslA
- bacterial nitric oxide synthase
what does lethal toxin do?
interferes with host protective mechanisms and immunity
what does edema toxin?
impairs host defense to infection; tissue lesions, multi organ failure
what does the poly d glutamic capsule do?
inhibits host defense through inhibition of phagocytosis of vegetative cells by macrophages
understand how infection happens on the map on slide 25!!!!
- anthrax releases 3 things PA, LF, and EF
- PA binds to ATR a receptor on the host cell
- furin binds to the receptor and cleaves off a subunit (PA20) from PA
- then I think through lipid rafts and dimerization a heptamer is made
- then the LF or EF binds to the heptamer
- the heptamer with the toxin/factor is brought into the cell
- inside the cell, while in an endosome the heptamer releases the factor/toxin
8A. if EF is released, the cAMP levels increase leading to edema
8B. if LF is released, then MAPK (MAP kinases) levels decrease leading to necrosis and hypoxia
what are the two types of definitive diagnostic tests?
rapid confirmatory tests and direct culture on standard blood agar
what are some characteristics of the blood agar diagnostic?
- gold standard, widely available
- sensitivity depends on severity, prior antibiotic treatment
- requires biochemical tests for 99% confirmation
what is the role of rapid confirmatory tests?
to confirm if cultures are negative
which form of anthrax is resistant to antibiotics?
the spore form. antibiotics work on germinating or vegetative form
empirically, what are the antibiotic combinations used to treat anthrax?
- ciprofloxacin alone
2. doxycycline with one or two other antibiotics (could be penicillin or aminoglycosides)
if ciprofloxacin and doxycycline is not available, what other antibiotics could be used?
penicillin, amoxicillin, gentamicin, streptomycin, erthyromycin, chloramphenicol
what antibiotics are ineffective against anthrax?
trimethoprim/sulfamethoxazole and third generation cephalosporins
what is an adjuvant?
a substance that enhances the body’s immune response to an antigen; can be inorganic or organic substance
how is the adjuvant for anthrax made?
from inactivated, cell free filtrate obtained from cultures on an avirulent, nonencapsulated strain of B. anthracis
