Lecture 8 - Bacillus Anthracis & Mycobacteria Flashcards
name 2 intracellular bacteria
listeria monocytogenes and bacillus anthracis
is bacillus anthracis encapsulated?
YES – polysaccharide capsule – helps it evade phagocytosis
is bacillus anthracis gram positive or gram negative? what shape is it?
gram positive rods
does bacillus anthracis form spores?
YES – they can survive for decades
bacillus anthracis is ____ hemolytic.
is it motile
non hemolytic and non motile
is bacillus anthracis aerobic or anaerobic or facultative?
either aerobic or facultative
how is bacillus anthracis transmitted?
through infected animals and animal products (food)
bacillus anthracis colonies form…
a “medusa head”
which bacteria is a bioterrorism threat?
bacillus anthracis – pulmonary anthrax
how can bacillus anthracis be transmitted?
most commonly through contact with animals (SPORE TRANSFER) BUT it is a bioterrorist threat – the spores can also be inhaled in that case but it’s obviously rare (this causes anthrax pneumonia).
in the case of anthrax pneumonia, the toxins and bacteria can get into the bloodstream
explain the toxin of bacillus anthracis
it is a potent exotoxin complex
anthrax toxin is an A-B toxin
the equivalent of the “B” subunit is PA (protective antigen) which binds to CMP-2 (capillary morphogenesis protein-2)
the 2 “A” toxins are EF (edema factor) which stimulates adenylate cyclase activity and LF (lethal factor). they form a dimer together
what is the result of the A-B exotoxin complex of bacillus anthracis
increased adenylate cyclase activity, which leads to inactivated production of host proteins
what kind of capsule does bacillus anthracis have
a glutamic acid capsule that helps it to evade phagocytosis
name the clinical diseases of bacillus anthracis
skin lesions (malignant pustules)
anthrax pneumonia (hemorrhagic – edema in chest. cells start to burst and blood starts to flow)
meningitis
is mycobacterium tuberculosis aerobic or anaerobic? gram positive or gram negative? what shape?
STRICT AEROBE
gram positive
it is a thin, club shaped bacilli
does mycobacterium tuberculosis have a capsule? is it motile? does it form spores?
no to all
what toxins does mycobacterium tuberculosis form
NO TOXINS
Explain what is unique about mycobacterium tuberculosis
it has no capsule, but has a unique cell wall. the cell wall is lipid rich and contains mycolic acid which gives it a WAXY COAT that is resistant to disinfectants, detergents, and stains
also, DNA has a high G/C content. most organisms are rich in A/T
Explain thoroughly the cell wall of bacillus anthracis
it is lipid rich which gives it a waxy coat, resistant to disinfectants, detergents, and stains
has mycolic acid
LAM (lipoarabinomannan) – carbohydrate like chains that anchor the cell wall to the membrane
60% lipid and 15% transport proteins and pores PPD — purified protein derivative
what is the only known reservoir of mycobacterium tuberculosis?
humans
true or false
mycobacterium tuberculosis is highly infectious
true
how can mycobacterium tuberculosis be transferred
humans are the only known reservoir
can be through respiratory or direct contact
in which parts of the world is mycobacterium tuberculosis most prominent
south africa and parts of south america
how does mycobacterium tuberculosis normally get in? where does it colonize?
normally gets in through inhalation
colonizes alveolar macrophages
explain how mycobacterium tuberculosis and listeria monocytogenes have a similar pathogenesis
both replicate intracellularly
they stop the actions of lysosomes in macrophages to evade the immune response
does inflammation occur with the infection of mycobacterium tuberculosis ? explain
yes — there is localized inflammation due to infected macrophages
explain what happens if a mycobacterium tuberculosis infection persists
large, necrotic granulomas form on the lungs (black patches)
what can you say about the primary infection with mycobacterium tuberculosis
it can be eliminated or it can persist for YEARS and form the large granulomas on the lungs. it never forms an active disease tho bc the immune system keeps it in check
when does an ACTIVE mycobacterium tuberculosis infection manifest itself? (secondary infection)
usually with increasing age of suppression of the immune system
what can you say about the spread of mycobacterium tuberculosis throughout thr body
it is commonly just localized to the lungs (alveolar macrophages) but it CAN disseminate and spread
explain the immune response to a mycobacterium tuberculosis infection and explain why that response occurs
you get the intracellular immune response bc mycobacterium tuberculosis is an intracellular bacteria – IFN gamma, etc
