Skin Infections

Question 1

What percentage of GP appointments are skin related?

Answer 1

15%

25% are skin infections

Question 2

Where are skin conditions more common?

Answer 2

Hot, humid climates amongst the poor

Question 3

Describe Staphylococcus aureus

Answer 3

Gram positive
Commensal in 30% of humans
Colonisation in nose, axilla and groin.

Question 4

What is the most common bacterial cause of skin infections?

Answer 4

Staphylococcus aureus

Question 5

Name some skin infections caused by S.aureus

Answer 5

Impetigo
Folliculitis
Boils
Carbuncles

Question 6

Give an example of a disease caused by S.aureus via the production of toxins

Answer 6

Staphylococcal scalded skin syndrome

Question 7

Describe Treponema palladium and the disease it causes

Answer 7

Gram negative spirochaete
Causes syphilis (usually an STI)

Question 8

Outline the stages of Syphilis and their respective symptoms

Answer 8

1. Primary- painless ulcers (chancre) at site of inoculation
2. Secondary- maculopapular rash and lymphadenopathy
3. Latent- asymptomatic
4. Tertiary- gummatous (non-cancerous soft tissue growth in syphilis) skin lesions, neurological and vascular manifestation

Question 9

How is Syphilis treated?

Answer 9

No vaccine, use antibiotics

Question 10

What is the route of transmission in congenital syphilis?

Answer 10

Vertical transmission from mother to child

miscarriage, still birth, premature, bone disease etc

Question 11

Describe HSV in particular types 1 & 2

Answer 11

Members of HHV (human herpes virus)- Large DNA virus
Type 1- causes oral infections
Type 2- causes genital infections

Question 12

What is the mode of transmission of HSV 1 & 2

Answer 12

Direct contact

Question 13

Give some clinical features observed in HSV 1 & 2

Answer 13

1. Painful vesicular rash (heals over 2-4 weeks, appears in same place as multiple blisters)
2. Eczema herpeticum
3. Eczema encephalitis

Question 14

How does T.pallidum affect the transmission of HIV?

Answer 14

Increases HIV transmission

Question 15

What is the reactivation and reinfection seen in HSV 1 &2 and VZV due to?

Answer 15

Latency period

Question 16

How are HSV 1&2 treated?

Answer 16

No vaccine, use antivirals like Acyclovir

Question 17

Describe VZV and the disease it causes?

Answer 17

varicella zoster virus (also a HHV), causes chickenpox mainly in those younger than young adults, causes shingles in adults
-widespread vesicular rash

Question 18

Why can there be serious consequences with VZV infection?

Answer 18

Affects CN V1 (ophthalmic branch of trigeminal nerve)

Question 19

Is there a vaccine for VZV?

Answer 19

yes, can also use antivirals

Question 20

What is a dermophyte?

Answer 20

type of fungus that particularly affects parts of the body that have keratin e.g Trichophytum rubrum

Question 21

Describe Tricophytum rubrum

Answer 21

• dermophyte

- common cause of superficial fungal infections

Question 22

What infections are associated with T.rubrum?

Answer 22

Tinea capitis (scalp)- Kerion is a type 
Tinea mauum (hand)

Question 23

State another form of fungal infection distinct from dermophytes.

Answer 23

Yeast e.g Candida

-grows on war wet surfaces (aka thrush when in mouth)

Question 24

What are some clinical features of an infections with T.rubrum?

Answer 24

1. erythromatous scaly rash on skin/scalp

2. discoloured or crumbly nails

Question 25

What is Scabies?

Answer 25

skin infestation by the mite Sarcopetes scabei

Question 26

Outline the pathogenies of Scabies

Answer 26

1. mite burrows into surface of skin, exposure to faeces and eggs causes a delayed-type allergic reaction.
2. leads to widespread eczematous rash approx 4 weeks after first infestation
   - very itchy

Question 27

Where are the burrow sites in Scabies?

Answer 27

Genital regions
Nipples
Axilla
Wrists
Finger webs

Question 28

How is Scabies transmitted?

Answer 28

Skin-skin contact

Question 29

How is Scabies treated?

Answer 29

Topical systemic insecticide