deck 9 Flashcards
which type of virus is commonly associated with pastries?
Norovirus
If a blood culture grows gram + spore forming rods, which two types of bacteria should you immediately think of?
1) Bacillus cereus2) Bacillus anthracis
T/F Most individuals are immune to the toxins released by Diphtheria?
True. We have corynebacteria as part of our normal flora, and since we are vaccinated against it as children, it hardly ever causes problems in the USA.
what type of bacteria is Corynebacterium diptheria?
Gram + rod that releases an exotoxin.
What do high iron levels do to the diphtheria toxin?
High iron levels function as co-repressors of exotoxin production.
How do bacteria make the active diphtheria toxin?
It starts out as a very long chain that is nicked into two parts. Part A=active enzyme, Part B=cell binding. (part B binds and facilitates the entry of Part A)
Once part A of the diphtheria toxin makes it into the cell, what does it do?
It catalyzes this rxn: Product inactivates protein synthesis(A + NAD + EF-2 –> A + N + ADPR-Diphthamide-EF-2)
Where do you usually find staphylococcal enterotoxin A?
It is a common superantigen agent that frequently results in food poisoning.
What causes hemolytic uremic syndrome?
Shiga like toxin
Scarlet fever toxin, staphylococcal enterotoxin A, cholera toxin, shiga like toxin, and diptheria are all examples of what?
Bacteriophage encoded exotoxins
Were does diphtheria usually colonize?
The pharynx, larynx, and nose.
What does the diphtheria toxin do to those individual susceptible to it?
kills epithelial cells and infiltrating PMN’screates an ulcer which is convered with with necrotic exudate forms what is called a pseudo membraneReleases toxin
What is are the classic signs of acute diphtheria toxin?
bull neck appearance with internal pseudomembrane.
what is the major way in which diphtheria kills the patient?
It stops their heart
Does diphtheria effect the blood and lymphatic tissue?
Yes. This is how it kills.
what major problems can diphtheria cause?
1) Fever, vomiting, diarrhea2) Myocarditis (This is how it usually kills)3) polyneuritis (demyelination leading to paralysis of the soft palate)
How do you diagnose someone who has diphtheria?
1) pseudomembrane 2) detection of exotoxin3) bull neck appearance
How do you treat someone with diphtheria?
1) treat with antitoxin 2) use antibiotics (penecillin/erythromycin because it is sensitive to most antibiotics)3) Tracheotomy if needed.
How do you prevent diphtheria?
DTaP vaccine
How often is the DTaP vaccine given?
It is given as a series of 5. 2, 4, 6, 18 months, then at 4-6 years of age. The tetanus vaccination needs to be renewed every 10 years thereafter.
where do you generally find listeria monocytogenes contamination?
cheeses or machinery used to process foods.
T/F listeria monocyogenes can infect a pregnant woman and transverse across the placenta to the fetus?
TRUE
T/F To help kill listeria monocytogenes, you should give the antibiotic vancomycin?
false. It is an intracellular pathogen so antibiotics do not help kill it off.
Why do you see granulomas with listeria monocytogenes?
It is because the organism escapes the phagosome within the macrophage and so it doesn’t become killed. This means that the body tries to wall it off like it does with tuberculosis.
what protein allows listeria monocytogenes to escape the phagosome?
Listeriolysin O. (it is a hemolysin)
why are CD8 cells heavily involved in killing listeria monocytogenes?
it is because it is an intracellular pathogen. This would be presented on MHC I and presented to CD 8 killer cells which would activate the macrophage.
Who do listeria monocytogenes usually infect?
immunocompromised individuals and developing fetuses.
What is listeria monocytogenes major virulance factor?
intracellular survival by escaping the phagosome
What does the protein internalin do?
Its a surface protein that helps listeria with invasion of cells
How do listeria monocyoges get from one place to another?
Flagella through actin polymerization. This is due mainly to ActA and gelsolin proteins. This may also help them to invade neighboring cells.
What do you often see with dysentery?
bloody diarrhea.
listeria monocytogens has a trophism for what?
CNS
What should you always think when you see gram + motile rods?
listeria monocytogenes
T/F Meningitis is commonly caused by listeria?
True in neonates;1) 40% group B strep2) 40% E. Coli3) 10% listeria
If you see a spore forming Gram + aerobe, what should you be thinking?
B. anthracis or B. cereus
T/F B. cereus is one of the first organisms shown to cause disease?
False, It is B. Anthracis
How big are the Bacillus bacteria?
about 10um by 2um (the spores are about 1um)
How do you differentiate Bacillus anthracis from bacillus cereus?
B. Anthracis:non hemolytic, non motile, medusa head colonyB. Cereus:hemolytic, non motile
What is the only organism with the poly D acid capsule?
Bacillus anthracis
How is B anthracis transmitted?
through highly resistant spores. Humans exhibit moderate resistance to infection.
How do you usually acquire B cereus?
From starchy foods in restaurants (food poisening). Note that you can also get spores into wounds that will grow and cause necrotizing fasciitis/myositis.
T/F B cereus food poisoning presents just like S. aureus food poisoning?
TRUE
Is B anthracis endemic to the soil of the midwest?
Well it can be in certain areas like Minnesota.
What is the #1 biotoxin in the world?
Enterotoxin B from staph because you cannot denature it.
What antibiotics is B anthracis sensitive to?
every antibiotic
Once a spore from anthrax enters the skin wound, what happens?
2-10 days later you see a lesion.Pustule to eschar progressing to a black scab.
what prevents phagocytosis of B anthracis?
Its capsule made of poly d glutamic acid!
How do anthrax toxins work?
You have an A part and a B part.The A part can either be the lethal factor or the edema factor. The B part is the homo heptamer circle carrier that allows it to bind the cell. When they are put together, they cause disease.
Protein A lethal factor is what kind of protein?
protein kinase protease
Protein A edema factor is what kind of protein?
adenylate cyclase protein.
In a bioterrorist attack with anthrax, how long would it take to see symptoms and where would you see the effects?
1-2 days and you would see it in the mediastinum where the spores would have been carried from the lungs to germinate.
What would you see (symptoms) with inhalation of anthrax?
1-2 days you would see massive edema of the neck, chest, and mediastinum. You would see fever, respiratory failure, and septiciemia.
What would you expect with ingestion of anthrax?
high fever, hypotension, shock and death. NOTE: these sympotoms parallel typhoid fever.
Why do you see a widening of the mediastinum with anthrax exposure to the lungs?
Because the spores have been carried to the local lymph nodes by phagocytes and are now causing edema/inflammation.
T/F antibodies are available for anthrax exposure?
True. IVIG from the military against the protective antigen
B. cereus food poisoning usually occurs in 2 ways which are?
1) ingesting pre-formed toxin2) ingesting spores
Which toxin is usually associated with starchy foods such as grains, rice, and potatoes?
B cereus toxin
when you get food poisoning from eating pre-formed enterotoxins of B cereus, what symptoms would you expect?
Vomiting & diarrhea in 2-8 hoursNO FEVER
when you get food poisoning from eating spores of B cereus, what symptoms would you expect?
vomiting and diarrhea in 24-48 hoursNO FEVER
T/F B cereus will cause highly lethal necrotizing fasciitis?
True. This will be accompanied by HIGH FEVER, hypotension, shock, and even death.
Which 3 types of bacteria are known to cause necrotizing fasciitis?
1 cause is group A strep#2 cause is staph aureus#3 cause is Bacillus cereus
