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Infectious Disease Final > Lecture 8 -- Corynebacterium & Listeria > Flashcards

Lecture 8 -- Corynebacterium & Listeria Flashcards

1
Q

are corynebacterium, listeria, and bacillus spore forming or non-spore forming? what is their shape?

A

spore-forming: bacillus
non-spore forming: corynebacterium and listeria

corynebacterium is CLUB SHAPED

bacillus and listeria are rods

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2
Q

is bacillus anthracis an aerobe or anaerobe?

A

aerobe

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3
Q

corynebacterium has a ___ shape while listeria monocytogenes is a ___ shape

A

corynebacterium has a IRREGULAR (club) shape, while listeria monocytogenes has a uniform shape

both are NON SPORE FORMING

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4
Q

give an example of an anaerobic spore forming rod

A

clostridium difficile

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5
Q

what can you say about a bacteria that has the ability to form spores?
also, give 2 examples of bacteria that can form spores

A

bacillus anthracis (aerobic) and clostridium difficile (anaerobic)

both can form spores, meaning that they can go dormant and survive in very harsh environments

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6
Q

what disease does corynebacterium diptheriae cause?
what toxin does it have?

A

diptheria
DT toxin (diphtheria toxin)

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7
Q

can corynebacterium diptheria form spores?

A

NO

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8
Q

is corynebacterium diptheria motile?

A

no

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9
Q

does corynebacterium have a capsule?

A

no

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10
Q

what is the source of corynebacterium diptheria?
what is the source of listeria monocytegenes?

A

source of corynebacterium diptheria = human carriers

source of listeria monocytegenes = food and animals

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11
Q

can listeria monocytogenes form endospores?
is it encapsulated?

A

no to both

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12
Q

is listeria monocytogenes motile?

A

yes

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13
Q

what disease(s) does listeria monocytogenes cause?

A

meningitis, bacteremia

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14
Q

what is the major toxin of listeria monocytogenes

A

LLO (listeriolysin O)

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15
Q

can bacillus form endospores?

A

yes

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16
Q

is bacillus anthracis encapsulated?
is it motile?
can it form endospores?

A

yes encapsulated
NOT MOTILE
can form endospores

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17
Q

what is the source of bacillus antrhacis

A

imported animal products

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18
Q

what disease(s) does bacillus anthracis cause

A

anthrax

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19
Q

corynebacterium diptheria is gram ____, catalase _____, and is ___ shaped

is anaerobic or aerobic?

A

gram positive
catalse positive
club shaped
aerobic

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20
Q

can corynebacterium diptheria form spores?

A

no

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21
Q

what is the only known source of corynebacterium diptheria? where specifically is it found?

A

humans – found on our skin and mucosal surfaces

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22
Q

corynebacterium diptheriae primarily affects which population?

A

pediatrics – their immune system isn’t as developed

23
Q

true or false

corynebacterium diptheriae produces lactic acid

A

true

24
Q

what is the MAJOR toxin of corynebacterium diptheriae

A

Diphtheria toxin. it is an A-B toxin (EXOTOXIN)

25
Q

general question: is an A-B toxin an endotoxin or exotoxin?

A

exotoxin

26
Q

explain in detail how diphtheria toxin works

A

A-B toxin

B subunit binds to EGFR on human surface (epidermal growth factor receptor)

A subunit inactivates EF-2 (elongation factor 2). doing this blocks host protein synthesis, since EF-2 is required for moving mRNA back and forth

a SINGLE MOLECULE of diphtheria toxin is enough to kill the entire cell due to the IRREVERSIBLE BLOCK of EF-2

as the cell gets destroyed, a “pseudomembrane” is produced by fibrin and the actual bacteria begin entering and replicating in the host cell. eventually, the toxin itself gets into the blood stream through the damaged cells. this is NOT bacteremia – the TOXIN is in the blood

27
Q

Explain how diphtheria toxin inactivates EF-2

A

CATALYTIC inactivation. it doesn’t just bind to it to inhibit it.

bc of this, a single molecule of Diphtheria toxin can kill the entire cell. it is an irreversible inactivation

28
Q

corynebacterium diphtheriae toxin infection is catalyzed by…

A

the delivery of TOXINS through the bloodstream

29
Q

name the different specific clinical diseases caused by corynebacterium diphtheriae

A

respiratory diphtheriae and cutaneous diphtheriae

30
Q

explain respiratory diphtheriae and what it can lead to if untreated

A

SUDDEN ONSET
occurs when corynebacterium diphtheriae colonizes the epithelium in the pharynx (causing pharyngitis)

the TOXIN is what brings about tissue damage — thick exudate is produced from this damage due to the formed pseudomembrane, white blood cells, fibrin, and debris

this exudate obstructs the airway (respiratory obstruction) and causes severe coughing which DISLODGES THE EPITHELIUM

if toxin gets into the blood and delivered to the heart, it can cause acute myocarditis

31
Q

diptheria primarily affects what population?

A

neonates

32
Q

explain cutaneous diphtheriae and what develops because of it

A

occurs when corynebacterium diphtheriae invades subcutaneous tissue.

pustules and ulcers develop

33
Q

is there a vaccine for diphtheria?

A

yes

34
Q

true or false

in a corynebacterium diphtheriae infection, ONLY the toxin gets into the bloodstream

A

TRUE

35
Q

how can a neonate get corynebacteriae diphtheriae?

A

usually by breathing it in (respiratory diphtheriae) or by contact with an open sore or ulcer (cutaneous diphtheriae)

36
Q

what is unique about listeria monocytogenes

A

it is capable of growing in very harsh conditions
4 degrees celsius
a wide pH range
high salt

also, it is intracellular – unique for bacteria

37
Q

how is listeria monocytogenes transmitted?

A

by exposure to contaminated food (food poisoning)

38
Q

is listeria monocyogenes gram positive or gram negative? is at aerobic or anaerobic? can it form spores? what shape is it?

A

gram positive rods
a facultative anaerobe (capable of producing energy with or without oxygen)
does not form spores

39
Q

listeria monocytogenes is ___ _hemolytic

A

weakly beta hemolytic – can lyse but it takes a while

40
Q

how does listera monocytogenes grow?
it is motile at what temperature?

A

often grows in pairs
motile at temperatures less than 37 degrees celsius

41
Q

true or false

listeria monocytogenes is an intracellular pathogen

A

TRUE – can grow and replicate inside of host cells. this is unique to bacteria

42
Q

explain how listeria monocyogenes invades

A

is ingested through contaminated food
then, it invades through MUCOSAL LINING of the GI tract and gets into the bloodstream to infect any neonate in the womb and cause meningitis

adheres to the host cell via INTERNALINS that bind to a host protein called E-cadherin. then, they are transported in via the GI tract M cells or enterocytes

43
Q

“listeria monocytogenes”

what can you remember by looking at the name of this bacteria?

A

they SURVIVE when they’re engulfed by macrophages. hence the name “listeria monocytogenes”

44
Q

explain HOW listeria monocytogenes can survive in macrophages

A

they have a toxin called LLO (listeriolysin O) which is a cytotoxin that stimulates the bacteria’s RELEASE from endosomes in the macrophage. also forms pores

45
Q

listeria monocytogenes primarily infects…..

A

both neonates AND adults

46
Q

explain the diseases that listeria monocytogenes can cause in neotnates

A

amnionitis
stillbirth
meningitis
meningoencephalitis

47
Q

explain the diseases that listeria monocytogenes can cause in adults

A

flu-like illness with possible gastroenteritis
bacteremia

48
Q

besides LLO, what other virulence factors does listeria monocytogenes have

A

Phospholipase C enzymes (2 of them) that break down the host cell membrane

ActA which induces actin polymerization

49
Q

true or false

listeria monocytogenes have some capability to evade the immune system

A

true – through their ability to replicate when phagocytised by macrophages

50
Q

As mentioned, listeria monocytogenes contains a virulence factor called ActA that stimulates actin polymerization.
what exactly does this do?

A

the bacteria utilize this polymerized actin to move through the host cell and even move along to infect OTHER cells

51
Q

recap: how does listeria monocytogenes adhere to the host cell

A

through internalins that bind to E-cadhedrin on the host cell

52
Q

what does listeria monocytogenes release that enables it to evade phagocytosis by macrophages?

A

LLO (listeriolysin O)

53
Q
A

Infectious Disease Final (13 decks)

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