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RC Test 4 > B4.072 - Strep Pneumo Capsular Model > Flashcards

B4.072 - Strep Pneumo Capsular Model Flashcards

1
Q

when dealing with a super antigen do you get a memory effect

A

no. T cells activated without priming

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2
Q

what can a capsule induce

A

antibody response in adults

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3
Q

what does a capsule prevent

A

opsonization and phagocytosis are reduced and thus phagocytosis is inhibited

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4
Q

what type of response is absent to capsules

A

T cell

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5
Q

antibodies to capsules

A

IgM and IgG2 and are short lived

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6
Q

describe IgM

A

high avidity low affinity and not

good at activating complement

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7
Q

IgM is poor at what

A

opsonizing

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8
Q

describe IgG2

A

main type produced in response to carbohydrates

CAN activate complement but cant bind to IgG Fc receptor so poor at opsonization

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9
Q

why is it not that great to produce IgG2 in response to capsular antigen

A

bc its not great at opsonization

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10
Q

what is in the capsule of GAS and why does that matter

A

hyaluronic acid

weakly immunogenic bc of similarity to hyaluronic acid in connective tissue

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11
Q

how does GAS cause strep throat

A

hyaluronic acid in capsule of GAS helps it attach to CD44 receptor in pharynx bc it is a hyaluronic acid receptor

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12
Q

describe the molecular mimicry in type B neisseria meningitidis

A

capsule contains sialic acid residues, similar to those in human cells, this inhibits both Ab production and alternative complement pathway

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13
Q

what is slime

A

carbohydrate coats around bacteria can be less well defined, this is called slime. Slime is often viscous and sticky which allows bacteria to attach to surfaces like catheters and teeth but also to glide

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14
Q

what is glycocalyx

A

capsules and slime can be generically called glycocalyx. Not all glycocalyces are composed of carbs

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15
Q

what bacteria is an example of a capsule not made of carbs

A

bacillus anthracis, has a capsule made of poly D glutamic acid

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16
Q

how can strep pneumo acquire another serotype from another bacterium?

A

transformation - bacteria can take up DNA from the environment

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17
Q

what other bacteria can transform

A

E. coli

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18
Q

what is conjugation

A

when two bacteria get together and transfer DNA

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19
Q

what is transduction

A

ability to transfer defined foreign sequences via vector

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20
Q

what are bacteria that can naturally carry out transformation

A

competent

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21
Q

is strep pneumo competent

A

yes naturally, no induction needed

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22
Q

how can e coli be induced to become competent

A

shock, new media

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23
Q

do all strep pneumoniaes have a capsule

A

no, just pathogenic ones

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24
Q

what is dessication

A

ability to survive harsher environments, capsule helps with this

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25
Q

difficulties in producing antibodies to a bacterial capsule inhibit what immune functions

A

T cell response
antibody opsonization
activation of C’ by classical pathway
physically protects bacterium

26
Q

to T cells respond to carbohydrates

A

no, bc they wouldnt necessarily recognize them as foreign bc MHC doesn’t present them. MHC only presents amino acid sequences.

27
Q

do antibodies respond to carbohydrate

A

yes

28
Q

major encapsulated pathogens

A 
Some Killers Have Pretty Nice Capsules
S - strep pneumo
K - klebsiella
H - H. influenzae b
P - pseudomonas
N - niesseria meningitidis
C - cryptococcus neoformans (yeast)
29
Q

if capsule is so protective for bacteria how come we arent all dead from pneumonia

A

adaptive immunity
when you are exposed more than likely its when ur a kid and its an ear infection. When the bacteria die they shed their capsule. This exposes their protein contents (conj carbs) producing an immune response

30
Q

why do older people get sicker with strep pneumo more than young ppl

A

impaired immunity
esp past 80
immunizing old people is hard bc of this
greater propensity to make IgG2 which doesnt opsonize well

31
Q

how is pneumococci spread

A

aerosols. harbored in nasopharynx

32
Q

most serious development of pneumocci infection

A

meningitis

33
Q

what is phosphorycholine

A

on the surface of pneumococcus
by mimicking PAF binds to the host cell PAFr leading to the uptake of bacteria into a vesicle and transmigration across the epithelial or endothelial barrier

34
Q

how do vaccines to capsules work

A

they are attached to another immunogenic molecule like diptheria toxoid

35
Q

what does the diptheria vaccine contain

A

toxoid, NOT the bug itself bc if it doesnt have the toxin who tf cares

36
Q

polysaccharides from the encapsulated bacteria that cause disease in early childhood cause what

A

stimulate B cells by cross linking the B cell receptor and drive the production of Igs but no production of new memory B cells such that subsequent immune responses are decreased

37
Q

why does conjugating polysaccharides with other toxoids cause an immune response

A

the carrier protein polysaccharide conjugate vaccineis processed by the polysaccharide specific B cell and peptides are presented to carrier peptide specific T cells resulting in T cell help for the production of both plasma cells and memory B cells

38
Q

with T cell help what IgGs are made

A

IgG1 and IgG3

good at opsonization, can activate complement and have high affinity

39
Q

there are cojugated vaccines for what organism

A

strep pneumo
neisseria
haemophilus influenzae a and b
influenza

40
Q

why is kids having an ear ache caused by strep pneumo protective long term for creating an immune response against the capsule?

A

bc the breakdown of dead cells causes a combo of protein (antigen/toxoid) and capsule polysaccharide essentially creating a conjugated vaccine

41
Q

strep pneumo is a major cause of pneumonia in what population

A

alcoholics and HIV

42
Q

HIV is a T cell issue, why would AIDS pts have issues with strep?

A

Bc you dont have T cells to present to stimulate class switching it IgG1 and IgG3

43
Q

what virus is also a risk factor for strep pneumo infection

A

influenza

44
Q

describe strep pneumo

A 
gram + cocci that grow in chains in liquids but in pairs
they are alpha hemolytic
catalase negative
\+ quellung test
soluble in bile salts
Optochin susceptible
45
Q

what is ethylhydrocupereine dihydrocholirde

A

optochin

46
Q

pathyphys of strep pneumo and how do viruses affect it

A

invasive disease may occur upon acquisition of a new epithelium serotype
viral infections increase pneumococcal attachment to the receptors on activated respiratory epithelium

47
Q

what is pneumolysin

A

strep pneumo produces pneumolysin which is toxic to mammalian cell membranes by inducing pores. Can induce lysis in neutrophils

48
Q

what causes symptoms of strep pneumo infection

A

largely due to an inflammatory response that may
cause pain by increasing pressure (otitis media), interfere with vital bodily functions, such as oxygenation of blood (pneumo)
interfere with cerebral function (meningitis)

49
Q

distinctive signs and symptoms of pneumococcal pneumonia

A 
cough and sputum production (rust colored)
fever
radiographic detection of an infection
WBC >12,000
neutrophil leukocytosis
\+ blood culture
50
Q

what causes rust colored sputum in strep pneumo

A

breakdown of blood vessels

51
Q

what causes fever in strep pneumo

A

breakdown of cells releasing acute phase reactants IL-1, IL-6, TNF inducing fever

52
Q

what plays a role in immunity to strep pneumo

A

phagocytosis by neutrophils (macrophages)

opsonization by antibody or C’ is crucial

53
Q

innate immunity components with strep pneumo

A

TLR 2 major receptor on cell surface of macrophages that recognizes it first

54
Q

what is teichoic acid

A

part of what activates the alternative C’ pathway in strep pneumo

55
Q

what components of strep pneumo cause an immune response

A

teichoic acid, peptidoglycan, C substance in cell wall - alternative C’
IgA - IgA1 protease
CRP can activate the classical C’
all recruit neutrophils

56
Q

which cytokines play a major role in strep pneumo immunity

A

IL-23 stimulates IL-17, IL-31, IL-22

57
Q

strep pneumo produces a protease to breakdown IgA1, why does this matter

A

IgA1 is the predominant form found in the blood

58
Q

IgA1 is usually produced in response to what

A

carbohydrates, hence why capsule of strep stimulates this response

59
Q

recent studies indicate TLR-8 produced by dendritic cells can play a role in the innate immunity to strep pnuemo. How?

A

recognizing unmethylated CpG found in bacteria and viruses

TLR 9 is intracellular

60
Q

which acute phase cytokine will mainly be responsible for differetiation of Th17 cells

A

IL-6 - IL-23 does too but is not an acute phase reactant

61
Q

complement can be activated against strep pneumo. what i the role of C’ protection against it?

A

recruitment of neutrophils and opsonization

62
Q

what are resistant to MAC

A

gram + orgs

RC Test 4 (10 decks)

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