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Flashcards in Microbiology Deck (128)
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1

What is virulence?

the capacity of a microbe to cause damage to the host

2

What are virulence ffactors?

The factors responsible for the variation in virulence within and between species

3

What is adhesin?

enables binding of the organism to host tissue

4

What is invasin

enabled the organism to invade a host cell/tissue

5

what is impedin?

enables the organims to avoid host defense mechanisms

6

What is aggressin?

causes damage to the host directly

7

What is modulin?

induces damage to the host indirectly

8

Where is S.aureus found on the body?

anterior nares and perineum

9

What skin diesases can Staph. aureus cause?

rash; folliculitis; carbuncle; impetigo; abscess; scalded skin syndrome

10

What do adhesins bind to?

extracellular matrix molecules that are present on cell surfaces

11

Give 2 examples of adhesins?

fibrinogen-binding
collagen-binding

12

What disease does collagen-binding factor allow Staph. aureus to cause?

osteomyelitis

13

Do all Staph. aureus have all virulence factors?

No

14

What is the purpose of hte capsule?

a thick polysaccharide layer that allows bacteria to evade and hide from the immune system

15

What is a toxinoses?

It is a disease that isn't caused by the bacteria itself but by the toxin it produces

16

What is a superantigen?

Doesn't bind directly to MHC class 2 complex but binds outside conventional binding groove which causes a cytokine storm and inappropriate immune response

17

Give an example of a superantigen

TSST-1

18

What disease does TSST-1 cause?

Toxic Shock Syndrome

19

What are the symptoms of Toxic Shock Syndrome?

fever
diffuse macular rash and desquamation
hypotension
more than three organs involved

20

What does Panton- Valentine Leukocidin do?

specific toxicity for leukocytes so stop immune system working

21

What conditions is PVL associated with?

recurrent furunculosis
sepsis/ necrotising fasciitis
necrotising pneumonia

22

Why do antibiotics fail in the treatment of necrotising penumonia?

The toxin is causing the disease not the bacteria and the antibitocs do not target the toxin

23

Describe Streptococci

gram positive cocci
chains
coagulase negative

24

What skin infections does streptococcus pyogenes cause?

impetigo, cellulitis, necrotising fasciitis

25

If a microbe causes beta haemolysis, what does this mean the bacteria can do?

produce a protein that can destroy RBCs

26

What proteins are involved in helping Strep. pyogenes in adhesion?

M proteins

27

What superantigens cause Toxic shock like syndrome?

SpeB and SpeC

28

What allows both Staph. aureus and Strep. pyogenes to cause Toxic Shock?

Similar exo-proteins, common virulence factors and disease mechanisms

29

What is variation in disease and virulence the result of?

variation in genes

30

How do staphylococcus sp. appear on staining

gram positive cocci in clusters