7.4 streptococcus pyogenes

Question 1

main strep group lancefield worked with

Answer 1

strep A

Question 2

what is streptococcus pyogenes also called

Answer 2

group A strep

Question 3

group A strep are exclusively

Answer 3

human pathogens, gram+ bacteria

Question 4

strep A causative agent of __ and can also cause infections of

Answer 4

strep throat
- can also cause infections of the inner ear, skin.

Question 5

what is responsible for the symptoms of scarlet fever

Answer 5

certain group A strains carry lysogenic bacteriophage that encode endotoxins

Question 6

untreated or insufficiently treated infections can lead to other disease like

Answer 6

rheumatic fever – can lead to rheumatic heart disease later in life

Question 7

how does rheumatic fever later lead to heart disease

Answer 7

thew antibodies that are generated in response to recognition of strep A do their job. but these antibodies also recognize individuals own heart tissue – resulting in heart lesions

Question 8

strep A can cause life trheatening disease..

Answer 8

flesh eating bacteria – necrotizing faciitis

Question 9

what happens during necrotizing faciitis

Answer 9

bacteria colonize the fascia – adhesion of bacteria destroy connective tissue and cartilage and keep multiplying – dead tissue must be removed surgically – can lead to amputation or death

Question 10

genes within PAI are ___ during infection to___

Answer 10

upregulating during infection to promote colonization and disease

Question 11

how is upregulation of PAI achieved

Answer 11

with dedicated transcription regulators – Mga - multigene activator

Question 12

what does Mga do

Answer 12

activates expressions of genes in multiple PAIs leading to disease progression

Question 13

two component regulator system – the two components

Answer 13

a membrane-bound sensor
a cytoplasmic response regulator that interacts directly with DNA to control transcription

Question 14

basic mechanism of the two component regulatory system

Answer 14

• membrane bound sensor is phosphorylated in response to stimulus
• relays the phosphate to cytoplasmic response regulator
• the regulator then interacts directly w DNA to control transcription

Question 15

what type of things are encoded by the highly regulated genes

Answer 15

surface proteins for protection, adhesion, and target destrcution
– toxins

Question 16

M protein

Answer 16

anchored in the peptidoglycan and protrudes far out from cell
– protein mediates attachment to host cells and interferes with pahgocytosis
– expression of M protein is controlled by Mga

Question 17

FBI fibronectin binding protein

Answer 17

anchored in peptidoglycan
- facilitates binding to the fibronectin on the surface of host cells
- promotes biofilm production
- bacteria are able to evade antibodies

Question 18

streptolysin O

Answer 18

-secreted pore forming toxin,
- promotes resistance to phagocytosis bc binds to cholesterol on surface of neutrophils and forms pores in their membranes

Question 19

ScpA

Answer 19

under control of Mga
- surface associated protein – cleaves and inactivates C5a, – component of innate immune system complement

Question 20

SpyCEP

Answer 20

surface associated protein that cleaves and inactivates interleukin-8
- destroys IL therefore pathogen can avoid host innate immune response

Question 21

what is IL8

Answer 21

a cytokine - promotes immune response

Question 22

SPE

Answer 22

at least 11 of these proteins present
– regulated independently of one another
- some of these exotoxins cause massive systemic immunoactivation seen in toxic shock syndrome – therefore are called superantigens