7.2: Pathogenesis and Virulence 2

Question 1

MRSA stands for

Answer 1

methicillin resistant stapphylococcus aureas

Question 2

MRSA is a gram ___ bacteria

Answer 2

positive

Question 3

MRSA colonizes what areas of the body?

Answer 3

moist squamous epithelium of skin and anterior nares (nasal)

Question 4

___% of people are colonized by MRSA, ___% are intermittent carriers and ____% dont have it

Answer 4

20; 60; 20

Question 5

MRSA can infect through (4)

Answer 5

skin abrasions, abscesses, burns, surgical sites

Question 6

MRSA is generally a ___ cause of pneumonia in the public

Answer 6

limited

Question 7

what type of MRSA is most associated with pneumonia?

Answer 7

HA-MRSA

Question 8

MRSA is a misnomer because

Answer 8

it was not always methicillin resistant, but developed over time

Question 9

CA-MRSA is associated with ___ infections

Answer 9

skin and soft tissue

Question 10

CA-MRSA is commonly acquired in what sort of settings/activities?

Answer 10

lots of people (prisons); contact sports such as wrestling, rugby etc

Question 11

CA-MRSA has a strong resistance to what type of anti-biotic?

Answer 11

beta lactamases

Question 12

why is CA-MRSA resistant to beta lactamases?

Answer 12

SCC mec cassettes

Question 13

SCCmec stands for

Answer 13

staphylococcal cassettes on chromosome

Question 14

what is a cassette?

Answer 14

group of genes

Question 15

SCCmec cassettes are ___ genetic elements that can move through cells by ____ transfer of genetic information

Answer 15

mobile; lateral

Question 16

there are ___ different types of SCCmec cassettes

Answer 16

5

Question 17

most MRSA strains have ___ type SCC mec

Answer 17

1-3

Question 18

CA-MRSA typically has ___ type SCC mec

Answer 18

4

Question 19

SCC mec carries ___ gene that codes for PBP 2a

Answer 19

mecA

Question 20

PBP 2a is a ___that prevents the action of which anti-biotic?

Answer 20

penicillin binding protein; penicillin

Question 21

SCC mec can be used as marker for a strain’s ___

Answer 21

history

Question 22

MRSA is slowly gaining resistance to what anti-biotic?

Answer 22

vancomycin

Question 23

VISA means ____ and VRSA means ___

Answer 23

vancomycin (Intermediate/Resistant) staph. aureus

Question 24

what drug can be used against VISA / VRSA strains?

Answer 24

Linezolid

Question 25

what is good about Linezolid? (3)

Answer 25

1. good activity against SA bacteria 2. good serum levels 3. active against MRSA, VISA, VRSA

Question 26

what are 2 drawbacks to Linezolid?

Answer 26

1. very expensive | 2. toxic to mitochondria and patient must be monitored

Question 27

what are 3 mechanisms leading to infection and disease by MRSA?

Answer 27

1. capsule 2. surface associated proteins and secreted toxin 3. immunodulatory features to promote colonization

Question 28

what is a capsule?

Answer 28

extra polysaccharide layer outside cell wall

Question 29

the capsule displays anti___ activity

Answer 29

opsonic

Question 30

the capsule prevents ____

Answer 30

opsonization (phagocytosis)

Question 31

what typically phagocytosizes bacteria?

Answer 31

neutrophils (immune system)

Question 32

MRSA strains are known to be able to survive within __-

Answer 32

neutrophils

Question 33

MRSA contains surface associated proteins and toxins that help ___ and ___ of host

Answer 33

adhesion to host and cell/tissue damage

Question 34

what enzyme mediates anchoring of bacterial proteins to the host cell wall?

Answer 34

sortase

Question 35

protein A binds to

Answer 35

IgG

Question 36

ClFA binds is a ___ factor that binds to ___

Answer 36

clumping; fibronectin

Question 37

what is fibronectin?

Answer 37

host cell surface protein

Question 38

immunodulatory features promote___

Answer 38

colonization

Question 39

Group A streptococci are a ___ relevant type of gram ___ bacteria

Answer 39

clinaically; gram +

Question 40

GA strept infects only

Answer 40

humans

Question 41

what is the major group of GA strept?

Answer 41

streptococcus pyogens

Question 42

what does streptococcus pyogens cause?

Answer 42

rheumatic heart disease (RHD)

Question 43

why does GAS cause rheumatic heart disease?

Answer 43

Cd4+ T cells recogize it, but the same antibodies react with heart tissue, causing lesions

Question 44

rheumatic heart disease is a type of ___ disease

Answer 44

auto-immune

Question 45

sore throat / stept throat

Answer 45

pharyngitis (non-invasive)

Question 46

Toxic shock syndrome

Answer 46

blood infection

Question 47

bacteremia can causes ___ borne infections such as :

Answer 47

blood; meningitis, septic arthritis, surgical site

Question 48

what can be caused by GAS?

Answer 48

1. phayngitis 2. toxic shock syndrome 3. respiratory and soft tissue infection 4. necrotizing fascitis 5. bacteremia and associated infections

Question 49

GAS is transmissible through

Answer 49

people in close contact

Question 50

genes within pathogenicity islands are upgraded during infection to promote ___

Answer 50

colonization and disease

Question 51

upgrading of genes in PAI is done by dedicated __

Answer 51

transcription regulators

Question 52

what 2 transcription regulating systems are involved in promoting upgrading?

Answer 52

Mga and 2 component regulatory systems

Question 53

what is mga? How do they affect virulence?

Answer 53

multigene activators. activate multiple genes during infection, leading to disease

Question 54

how do 2 component regulatory systems affect virulence?

Answer 54

allows bacteria to sense environment with 1 and regulate with the other. actiavtes virulence factors

Question 55

GAS has a variety of ___ that are produced to degrade tissues of host

Answer 55

toxins

Question 56

surface proteins allow for ___ destruction

Answer 56

targeted

Question 57

ScpA degrades ___ (specifically ___)

Answer 57

peptides; C5A peptidases

Question 58

SIC is a surface protein ____

Answer 58

streptococcal inhibitor of complement

Question 59

what is the complement pathway?

Answer 59

part of immune resposne (one of 1st responders against bacteria)

Question 60

surface proteins reduces host immune response by reducing ___ recruitment

Answer 60

neurtriphil

Question 61

Protein A binds to antibodies for the purpose of __

Answer 61

preventing them from binding to targeted antigen

Question 62

the clumping promoted by the ClFA/fibronectin complex produces __

Answer 62

biofilms