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Flashcards in Microbiology Deck (50)
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1

Define 'virulence'

The ability of an organism to cause disease within a host

2

Name 5 virulence factors

Adhesin
Impedin
Invasin
Aggressin
Modulin

3

What are adhesins?

Bacterial cell surface components that help the organism stick/adhere to host tissue

4

What are invasins?

Enable organisms to invade host tissue

5

What are impedins?

Help the organism avoid the defence/immune response in host tissue

6

What are aggressins?

Cause direct damage to host tissue + immune cells, affecting the host's ability to cope with disease in the future

7

What are modulins?

Cause indirect damage to the host by turning the immune system in on itself (host's immune system causes damage to host tissue)

8

The nasal strain of Staph. aureus can protect the mucosa. True/False?

True

9

Staph. epidermidis can occupy up to 100% of our skin. True/False?

True

10

Where is the most common entry of Staph. aureus into the body?

Nasal entry

11

Name the 3 particularly important virulence factors of Staph. aureus disease

Fibrinogen-binding protein (adhesin)
Leukocidin (kills leukocytes)
TSST-1 (toxin)

12

Every strain of Staph. aureus carries every virulence factor. True/False?

False

13

Which 2 severe skin diseases is leukocidin associated with?

Necrotising fasciitis
Recurrent furunculosis

14

Leukocidin is more virulent in hospital-acquired MRSA than community-acquired. True/False?

False

15

Give an example of a superantigen released by MRSA

TSST-1 (toxic shock)

16

How exactly do superantigens avoid specific T-cell activation?

Bind to MHC II complex on the outside, i.e. not the conventional binding groove

17

Name 3 skin infections caused by Strep. pyogenes

Impetigo
Cellulitis
Necrotising fasciitis

18

How does the Lancefield system classify different subtypes of Step. pyogenes?

M-protein
(M1 and M3 are predominant; M3 and M18 cause severe, invasive disease)

19

Which 2 virulence factors are particularly important as adhesins for Strep. pyogenes disease?

Hyaluronic acid (sticky capsule)
CD44 +ve keratinocytes

20

The bigger the capsule, the less virulent an organism is. True/False?

False

21

Where does impetigo usually affect?

Face

22

Where in the body is Strep. pyogenes normally found?

Throat

23

Which strain of Staph aureus commonly produces abscesses and boils, usually affecting numerous family members at once?

PVL (panton valentine leukocidin)

24

Which group of Strep causes throat and severe skin infections?

Group A

25

Which bacteria cause impetigo?

Staph aureus
Group A Strep

26

Which bacteria tends to cause nectrotising fasciitis?

Group A Strep (pyogenes)

27

What is the treatment of choice for Staph aureus?

Flucloxacillin

28

What is the treatment of choice for Strep pyogenes?

Penicillin

29

What is necrotising fasciitis?

Bacterial infection spreading under the skin into fascia

30

What is the nickname of necrotising fasciitis?

Flesh-eating bacterial disease