Virulence Flashcards Preview

Dermatology > Virulence > Flashcards

Flashcards in Virulence Deck (48):
1

What 3 things should be considered in infectious diseases

Symptoms
Organism
Virulence Factors

2

What part of the skin prevents colonisation of micro-organisms

The waterproof epithelial surface is constantly shedding and waterproof

3

Bacteria require iron. How do they obtain this

They rely on haemolysis of RBCs

4

What is virulence

The capacity of a microbe to cause damage to the host.
i.e what amount of organisms are required to cause death to the host
A measure of how well they can cause disease

5

What is adhesin

Enables binding of the organism to host tissue

6

What is invasin

Enable the organism to invade a host cell/ tissue

7

What is Impedin

Enables the organism to avoid host defence mechanisms

8

What is aggressin

Causes damage to the host directly
It affects the hosts ability to respond to diseas

9

What is Modulin

Induces damage to the host indirectly
Turn the immune system in in itself

10

What can lead to the amputation of limbs

Aggressins

11

What are the 3 main skin microbiota

Staplococci spp
Staphlococcus aureus
Diptheroids

12

If staph aureus is acquired in the community, what does it tend to lead to?

Serious skin infection

13

Staph epidermidiis is carried on most people but it only affects some. Who are these people

Immunocompromised

14

Who is at risk of developing MRSA

elderly and immunocrompromised
ICU
Burns patients
surgical patients
IV lines
Dialysis patients

15

Define nosocomial

Hospital borne infection

16

Why is staph aureus classed as a successful organism

Because it is so adaptive and therefore can survive in different environments

17

What makes a an organism successful

The number of virulence factors that lead to the organism to being adaptive

18

Name some virulence factors

Capsule
Fibrinogen Binding protein
Coagulase
Leukocidin
TSST-1 (toxin)
Enterotoxin
Adhesin
Clots plasma
Digests fibrin
Kills Leukocytes
Vomiting and Diarrhoea
Shock, rash, desquamation

19

Why might staph aureus cause a different reaction in different areas of the body?

Its ability to produce different virulence factors causing differences in disease

20

Give 2 examples of Adhesins

Fibrinogen-Binding (ClfA and ClfB)
Collagen-Binding (CNA)

21

How does protein A work to cause disease?

It stops the immune system from working as it binds the wrong immunoglobulin

22

What does PVL stand for

Panton Valentine Leukocidin

23

What is PVL and alpha toxin linked with

CA-MRSA

24

Describe the progression of necrotising pneumonia

Rapid progression

25

Why does giving a patient with necrotising pneumonia not help

The tissue is already being destroyed and the damage has already been made and is therefore too late to reverse this.

26

What superantigen is associated with Toxic shock

TSST-1

27

What does TSST-1 do

Cause a massive release of cytokines and an inappropriate immune response

28

Where does the super antigen become stabalised

Outside the cell and not in the cleft

29

What 4 things must a patient have for them to be diagnosed with a superantigen

Fever (39)
Diffuse macular rash and desquamation
Hypotension (

30

Describe the appearance of Streptococcus pyogenes

Gram +ve cocci
Chains
Catalase negative
Haemolysis

31

What skin infections are caused by streptococucus pyogenes

Impetigo
Cellulitis
Necrotising Fascites

32

What is the most common presentation of an infection of Streptococcus pyogenes

Sore throat

33

What is the purpose of the Lancefield system

it organises different groups of streptococci
Serotyping of the cell wall carbohydrate

34

What is the most important protein for adhesion

The M protein

35

How does the capsule work

It is part of the defences - it is an extracellular matrix that disguises the microbia

36

What makes up the capsule

Hyaluronic acid

37

What is the most common GAS skin disease

Impetigo

38

Give some features of Impetigo

Usually affects the face
highly contagious through contact with discharge on the face

39

What is the difference between Impetigo and Cellulitis

Impetigo is just below the surface of the skin in the stratum corneum
Cellulitis is a deeper skin infection not associated with necrosis

40

What generally happens with necrotising fasciitis

Damage to the tissue tends to be so bad that it leads to amputation

41

Toxic shock like syndrome TSLS is often associated with what

A pre-determined sore throat

42

What is the mortality rate with Pyrogenic exotoxins

30%

43

What is the onset of pyrogenic exotoxin

hours to days

44

What doesStreptococcus pyogenes target

White blood cells and the immune system

45

What two organisms can cause toxic shock

Staph aureus and Staph pyogenes

46

How does virulence vary

Variation caused by evolution- some proteins have an advantage of surviving in one environment than another

47

Where is Staph pyogenes normally found

In the pharynx and also adheres to skin

48

How can toxic shock be produced by both staph aureus and staph pyogenes

Due to their production of similar exo-proteins