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70 Cards in this Set

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Describe B. anthracis
G+/-
Spores?
Shape?
G+
Spore forming
Rod
What is the infectious dose for this organism?
2,500 - 10,000 bact
(~8000)
Where does this bact usually cuase disease?
In herbivores
How is this transmitted?
Animal to human if in contact with infected animal or contaminated animal products
What is the reservoir for this bacteria?
Soil
Describe the life cycle of this bact
Spores in the ground
Get ingested by cow
Germination and multiplication of the bacilli
Cow dies, spores released
Spore is what infects the organism
What are factors thatinduce sporulation?
O2
Temp
Nutrients
Sunlight
Ca2+, H2O
pH
Mn2+
Where do the spores go once they're ingested?
Go to the distal alveoli (perfect size to reach there)
Once there, get engulfed by macs
Goes from spore -> vegetative state and produces toxins
One of these toxins (LT), is a metal protease that cleaves MAPKK
Some macs go to megasomal LN and the bact get into the blood stream
Can get pulmonary edema
Can go to brain and kill you
What are the 2 toxins produced by B. anthracis?
Edema toxin (ET)
Lethal toxin (LT)
What does the CHR part of the bact include?
2 plasmids
pX01
pX02
What does pX01 make?
Edema and lethal factor
Can also cause disease in intestine (not as bad because doesn't cause infection a s fast)
When do flies play a role in transmission of this bacteria?
In enzootic areas
What are the initial symptoms of inhalation of this bacteria?
Fever
Cough
Myalgia
Malaise
=> looks like a cold or the flu
What are the terminal symptoms?
High fever, dyspnea, cyanosis
Hemorhagic mediastinitis, pleural effusion
Rapid progression to shock, death
->100% mortality even with aggresive treatment
How do you diagnose clinical inhalation of B. anthracis?
Immunochemical staining
B anthracis detected by PCR
Rise of anti-PA IgG
What kind of a disease is this?
Lung disease (not just a LN disease)
What is a dominant radiological feature of some patients?
Pulmonary infiltrates
What is an important feature of the illness?
Pleural effusion
What does acutaneous infection result in?
Black scar
What is the mortality rate of cutaneous anthrax infection?
20% if untreated
0% if treated
Which toxin is involved in cutaneous infection?
Edema toxin
->Causes swelling
How is gastrointestinal infection caused by this baceria?
Eat contaminated meat
What happens in this infection?
Same thing as in cutaneous infection
Intestinal eschar
Can lead to generalized toxemia
How can this be treated?
Doxycyclin
Fluroquinolone
-Usually use one of these in conjunction with 1 or 2 other drugs, to make sure that the drugs go into the CSF (also don't want disease resistance)
Can also use steroids
-Don't use cephalosporins
Is quarantine required for this bacteria?
No
What other treatment should be given?
Supportive care
Standard precautions (gloves etc)
Early treatment improves prognosis
What post-exposure treatment should be given?
Oral antibiotics: Ciprofloxacin or Doxycycline
Antibiotics for at least 100 days without vaccine
Antibiotics for 40 days with 3 doses of vaccine
Describe the current vaccine vs B. anthracis
FDA approved
Active component is protective Ag (PA) from an attenuated non-encapsulated strain
Protective vs cutaneous and maybe inhalation anthrax
-> Limited availability
What is the laboratory risk of B anthracis?
Lvl 2
(but once you grow it, it should be lvl3, since the spores can go everywhere)
What is a lvl A lab?
BSL-2 with class II bio saftey cabinets
Trained personnel in handling pathogenic agents
Containment practices to prevent aerosol transmission
What general tests are used to distinguish B. anthracis?
Phenotype (G stain)
Immunodetection: use enz assays
Sequence detection: genomics
What are key level A tests performed on B. anthracis?
G stain
Growth characteristics on agar
Catalase +
Sporulation in air
Lack of motility
Penicillin inhibition zone
Capsule formation
What are the presumptive identification characteristics of B anthracis?
Spores are oval
Non-swelling of vegetative cell
Ground glass morphology
What is the india ink stain for?
See if it has a capsule
-> if it does, will be a white clearance around the cell because ink can't go through
Is this bacteria motile?
No
How do you confirm if its a level B organism?
Phage lysis and Capsule tests
OR
DFA: Capsule Ag and Cell wall Ag

Phage lysis important
What's the problem with doing a bunch of biochemical tests on bacillus?
The species are very similar and produce similar results
What happpens when you look at the 16S rRNA?
B. cereus and B. anthracis have the same
And this test doesn't tell us if toxins are being produced
What is the test of choice?
PCR
-> look for B. anthracis DNA
-> can locate a plasmid
What is MLVA?
Multi-locus variable number tandem repeat analysis
-Have 8 markers
What can a spore resist?
Heat
UV and ionizing radiation
Pressure
Chemical agents
Survive decades
Describe B. anthracis interaction with macrophage.
Confocal mic
Phagolysosome
Express toxin genes
gerX on pX01
->Delete gerX, get reduced virulence in mice
5 loci other than GerXA/B/C encoding germination-like ptns on chr

-Germination loci
What factors are involved in the 2 toxins?
Lethal toxins: PA + LF
Edema toxins: PA + EF
What is PA?
EF?
LF?
PA: protective Ag, cell binding domain
EF: edema factor, enz
LF: lethal factor, enz
What is this toxin "trinity" required for?
Germination and survival in macrophages
What kind of toxins are the anthrax toxins?
Binary toxins
Effector + transporter
What does PA alone cause?
Immunity in guinea pig
Can EF or LF on its own, without PA, cause disease?
No, can't cuase either edma or lethality
What is the result of EF + PA?
Edema in skin of rabbit
Some immunity in pig
What is the result of LF + PA?
Lethality in mice
some immunity in guinea pig
What happens when EF + LF are combined together?
Can't get into the cell because there isn't any PA
What happens when EF + LF +PA are combined?
Increased lethality
What is the structural organization of PA, LF and EF?
PA has ATR-Type 1: mb ptn that binds to EF and LF
ATR: mb ptn with ectracellular von Willebrand factor A domain
What happens if a soluble receptor for the toxins is added to the culture?
Get decreased amount of toxin in the cell
.: cell is better protected
What is the cellular model of action of anthrax toxins?
83 unit PA attached
Furin-like enz cleave off 20 units -> PA63 (can be soluble)
PA63 becomes a heptamer tht can attach a total of 3 units (3EFs or 3 LFs or 1EF, 2 LFs etc)
At lower pH, form pore and toxins leave
What does EF affect?
ATF, cAMP is blocked through blockage of calmodulin
What does LF affect?
methylo enz proteases
Affects MAPKK, get death etc
What happens if inhibitors of endosomal acidification are added?
Prevent cytotoxicity
What happens if PA is blocked with Anti-PA antibodies?
No disease
Protection vs anthrax toxin
PA fcts as an adjuvant for LF Ab response
What are the targets of anthrax toxins?
All MAPKK (Meks1-7) except Mek5
What is involved in the action of anthrax toxins?
can have apoptotic factors
Affect many cytokines
Ltx1: mouse mac resist LT
NF-kB: TF regulating Immune Response
What ptn does edema factor need?
Calmodulin
-> Principal mediator of Ca2+ signalling
-> involved in gene T, ion conductivities, vesicular fusion and cytoskeleton fcts
What does EF-CaM do?
Inhibits Ca2+ binding and CaM fct (ex: cAMP ATP)
What is most importnat to the virulence of anthrax?
Plasmids
-> required to make toxins
Without them, no disease
What is important to plasmid virulence?
Temperature
Bicarbonate influences of capsule formation
AtxA: major regulator
What does pX02 encode?
Capsule
What happens if no pX02?
Bacteria exist without a capsule
Can cause disease in lung, but cannot disseminate everywhere
Is there a lot of spotaneous loss of pX01?
No
What does AtxA do?
Regulates capsule synthesis/degradation and germination
What do the plasmids encompass?
Pathogenicity island that can transpose