Lecture 8 - Bacillus Anthracis & Mycobacteria

Question 1

name 2 intracellular bacteria

Answer 1

listeria monocytogenes and bacillus anthracis

Question 2

is bacillus anthracis encapsulated?

Answer 2

YES – polysaccharide capsule – helps it evade phagocytosis

Question 3

is bacillus anthracis gram positive or gram negative? what shape is it?

Answer 3

gram positive rods

Question 4

does bacillus anthracis form spores?

Answer 4

YES – they can survive for decades

Question 5

bacillus anthracis is ____ hemolytic.
is it motile

Answer 5

non hemolytic and non motile

Question 6

is bacillus anthracis aerobic or anaerobic or facultative?

Answer 6

either aerobic or facultative

Question 7

how is bacillus anthracis transmitted?

Answer 7

through infected animals and animal products (food)

Question 8

bacillus anthracis colonies form…

Answer 8

a “medusa head”

Question 9

which bacteria is a bioterrorism threat?

Answer 9

bacillus anthracis – pulmonary anthrax

Question 10

how can bacillus anthracis be transmitted?

Answer 10

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

Question 11

explain the toxin of bacillus anthracis

Answer 11

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

Question 12

what is the result of the A-B exotoxin complex of bacillus anthracis

Answer 12

increased adenylate cyclase activity, which leads to inactivated production of host proteins

Question 13

what kind of capsule does bacillus anthracis have

Answer 13

a glutamic acid capsule that helps it to evade phagocytosis

Question 14

name the clinical diseases of bacillus anthracis

Answer 14

skin lesions (malignant pustules)
anthrax pneumonia (hemorrhagic – edema in chest. cells start to burst and blood starts to flow)
meningitis

Question 15

is mycobacterium tuberculosis aerobic or anaerobic? gram positive or gram negative? what shape?

Answer 15

STRICT AEROBE
gram positive
it is a thin, club shaped bacilli

Question 16

does mycobacterium tuberculosis have a capsule? is it motile? does it form spores?

Answer 16

no to all

Question 17

what toxins does mycobacterium tuberculosis form

Answer 17

NO TOXINS

Question 18

Explain what is unique about mycobacterium tuberculosis

Answer 18

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

Question 19

Explain thoroughly the cell wall of bacillus anthracis

Answer 19

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

Question 20

what is the only known reservoir of mycobacterium tuberculosis?

Answer 20

humans

Question 21

true or false

mycobacterium tuberculosis is highly infectious

Answer 21

true

Question 22

how can mycobacterium tuberculosis be transferred

Answer 22

humans are the only known reservoir

can be through respiratory or direct contact

Question 23

in which parts of the world is mycobacterium tuberculosis most prominent

Answer 23

south africa and parts of south america

Question 24

how does mycobacterium tuberculosis normally get in? where does it colonize?

Answer 24

normally gets in through inhalation
colonizes alveolar macrophages

Question 25

explain how mycobacterium tuberculosis and listeria monocytogenes have a similar pathogenesis

Answer 25

both replicate intracellularly
they stop the actions of lysosomes in macrophages to evade the immune response

Question 26

does inflammation occur with the infection of mycobacterium tuberculosis ? explain

Answer 26

yes — there is localized inflammation due to infected macrophages

Question 27

explain what happens if a mycobacterium tuberculosis infection persists

Answer 27

large, necrotic granulomas form on the lungs (black patches)

Question 28

what can you say about the primary infection with mycobacterium tuberculosis

Answer 28

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

Question 29

when does an ACTIVE mycobacterium tuberculosis infection manifest itself? (secondary infection)

Answer 29

usually with increasing age of suppression of the immune system

Question 30

what can you say about the spread of mycobacterium tuberculosis throughout thr body

Answer 30

it is commonly just localized to the lungs (alveolar macrophages) but it CAN disseminate and spread

Question 31

explain the immune response to a mycobacterium tuberculosis infection and explain why that response occurs

Answer 31

you get the intracellular immune response bc mycobacterium tuberculosis is an intracellular bacteria – IFN gamma, etc