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Flashcards in Microbiology Deck (50)
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

31

Type I necrotising fasciitis is caused by Group A Strep. True/False?

False
Type I = mixed anaerobes and coliforms
Type II = group A Strep

32

What is the most common skin fungal infection caused by?

Ringworm (Tinea)

33

Tinea pedis is another name for what?

Athlete's foot

34

How is dermatophyte infection caused?

Fungus enters abraded skin and infects keratinised tissue, provoking inflammation and outward lesioning

35

Which organism is the most common cause of dermatophyte infection?

Trichophyton rubrum

36

How are small areas of dermatophyte infection treated?

Clotrimazole cream
Nail paint

37

How are dermatophyte scalp infections treated?

Terbinafine oral
Itraconzole oral

38

Which parasite causes scabies?

Sarcoptes scabiei

39

Incubation of the scabies parasites takes up to how long?

6 weeks

40

How is scabies treated?

Malathion lotion overnight
Benzyl benzoate (not in children)

41

Chickenpox and shingles are due to which virus?

Varicella zoster

42

Where does varicella zoster become dormant following chickenpox?

Dorsal root ganglia of spine

43

Chickenpox can cause pneumonitis and encephalitis. True/False?

True

44

What is Ramsay-Hunt syndrome?

Reactivation of VZV in CN VII
Causes vesicles and pain in auditory canal and throat

45

What does herpes simplex virus cause around the mouth?

Primary gingivostomatitis
Extensive ulceration

46

What is the treatment of choice for varicella zoster and herpes simplex virus?

Aciclovir

47

Which virus tends to cause warts?

Human papilloma virus

48

Which treatment is effective for warts?

Salicylic acid

49

Which bacterium causes syphilis?

Treponema pallidum

50

How is syphilis treated?

Penicillin injections