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Flashcards in Infections Of The Skin Deck (32):
1

What are features of the skin as a defensive barrier?

+ Epidermis: hard horny layer of cells
+ Surface is dry
+ Constant sloughing
+ Acidic pH
+ Sweat secretion
+ Rich blood and lymphatic supply
+ Produces antimicrobial substances e.g
- fatty acids
- sebum
- defensins

2

What are examples of normal microbiota?

+ Coagulase-negative Staphylococci
- Staphylococcus epidermidis
- Staphylococcus aureus

+ Streptococcus pyogenes

+ Propionibacterium acnes

+ Corynebacterium sp.

+ Candida sp.

3

Where is the site of infection for ringworm?

Keratinised epithelium

4

What is the site of infection for impetigo?

Epidermis

5

Where is the site of infection for folliculitis?

Hair follicles

6

Where is the site of infection for cellulitis?

Subcutaneous fat

7

Where is the site of infection for necrotising fasciitis?

Fascia

8

Where is the site of infection for gas gangrene?

Muscle

9

What are the routes of infection?

Via:

+ Skin
- pores
- hair follicles

+ Wounds
- scratches
- cuts
- burns

+ Bites
- insects
- animals

10

Name some bacterial infections of the skin

+ Staphylococcus aureus
+ Staphylococcus pyogenes
+ Pseudomonas aeruginosa
+ Myobacterium tuberculosis

SOME MAY BE TOXIN MEDIATED

11

What are features of streptococcus pyogenes?

+ Cocci morphology
+ Grows in chains
+ Gram positive
+ Group A Streptococcus (GAS)
+ Multiple virulence factors
+ Beta-haemolytic

12

What are features of staphylococcus aureus?

+ Cocci morphology
+ Grows in clusters
+ Gram positive
+ Causes huge range of illnesses
+ Antibiotic resistant strains
- MRSA
- VRSA
+ Multiple virulence factors
+ Direct infection or effect of toxin

13

What are features pseudomonas aeruginosa?

+ Coccobacillus morphology
+ Gram negative
+ Monotrichous flagellum
+ Opportunistic pathogen
+ Colonises catheters etc.
+ Produces exotoxin A

14

What are different forms of skin lesions?

+ Macule
- raised
- red
- local inflammation

+ Papule
- raised
- red
- more marked inflammation

+ Vesicle
- small blister

+ Ulcer
- disruption of epithelium

15

What is an abscess?

Collection of pus; pustule

16

What is a (cutaneous) vesicle?

Blister; bullae (pl.); fluid filled sac

17

What is pyoderma?

Pus-forming skin infection; cutaneous abscess

18

What is impetigo?

Vesicles developing into rupturing pustules then forming dried crusts

19

What is ecthyma?

Rupturing vesicles leading to erythematous lesions and dried crusts

20

What is folliculitis?

Inflammation at hair follicle

21

What is a furuncle?

Boil; deep folliculitis

22

What is a carbuncle?

Collection of boils

23

What is erysipelas?

Erythema and inflammation of superficial dermis

24

What is cellulitis?

Erythematous inflammation affecting deeper dermis and subcutaneous fat

25

What is acne?

Infection of sebaceous follicles

26

What is necrotising fasciitis?

Cellulitis with necrosis affecting skin, deeper fascia and sometimes muscle

27

What is dehiscence?

Wound rupture along surgical suture

28

What are types of fungal infections?

+ Dermatophytes
Tinea app.
- Tinea pedis
- Tinea corporis
- Tinea cruris

+ Yeast
- Candida albicans
- Malassezia furfur

29

What are examples of viral infections of the skin?

+ Human papilloma viruses (HPV)
- warts

+ Herpes simplex virus 1 (HSV1)
- cold sores

+ Herpes simplex virus 2 (HSV2)
- genital warts

+ Varicella zoster virus (VZV)
- chicken pox
- shingles

+ Coxsackie A virus
- hand, foot and mouth disease

30

Give an example of a parasite of the skin?

Sarcoptes scabei (mite)

31

What does Sarcoptes scabei cause?

Scabies

32

What are the features of scabies?

+ Mite burrows into skin
+ Female lays eggs
+ Infection is asymptomatic
+ Hypersensitivity may occur
+ May lead to superinfection