Skin Infections

Question 1

Describe the epidemiology of skin disease

Answer 1

High rates in hot humid conditions and poor populations
Low rates in dry temperate conditions and rich populations
25% of GP skin consultations (UK)

Question 2

What proportion of skin disease presentations are of infectious cause in the GP vs hospital

Answer 2

GP - 25%

Hospital - 5%

Question 3

What are the manifestations of staphylococcus aureus skin infections

Answer 3

Impetigo - infection of sub corneal layer or epidermis
Folliculitis - infection of mouth of hair follicle
Ecthyma - Infection of full thickness of epidermis
Boli - abscess of the hair follicle
Carbuncle - abscess of several adjacent hair follicles

Question 4

Describe treponema pallidum

Answer 4

Gram negative spirochaete
Cause of Syphilis
Sexually transmited disease
12 million new cases per year worldwide
Increases transmission of HIV

Question 5

What are the stages of syphillis infection

Answer 5

Primary (3-8 weeks)
secondary (6-12 weeks)
Latent - non clinical signs
Tertiary (years later)

Question 6

Describe congenital syphillis

Answer 6

Acquired perinatally
Early and late manifestations

Miscarriage
Still birth
Prematurity
Rashes
Brain and neurological problems
Bone disease

Question 7

Describe primary, secondary and tertiary syphillis

Answer 7

primary - painless ulcer at inoculation site (genital or oral)

Secondary - Disseminated infection, Generalised rash and lymphadenopathy

Tertiary - Skin, neurological and vascular manifestations. Bone lesions and thoracic aneurysms

Question 8

Give the following features of HHV-1:
Synonym
Target cell
Disease
Site of latency

Answer 8

HSV type 1
Muco-epithelial
Oro-genital herpes
Neurone

Question 9

Give the following features of HHV-2:
Synonym
Target cell
Disease
Site of latency

Answer 9

HSV type 2
Muco-epithelial
Oro-genital herpes
Neurone

Question 10

Give the following features of HHV-3:
Synonym
Target cell
Disease
Site of latency

Answer 10

VZV
Muco-epithelial
Chickenpox/shingles
Neurone

Question 11

What are the clinical presentations of herpes simplex infection

Answer 11

Vesicular rash - 2 weeks
Eczema herpeticum
Herpes encephalitis

Question 12

What are the medical considerations of staphylococcus aureus

Answer 12

Commensal
Skin infections - most common cause
MRSA
Toxin production 
Bone, joint and lung infections 
Sepsis

Question 13

What toxins can S. Aureus produce

Answer 13

Panton Valentine Leuocidin
Exfoliative toxin
TSST-1 (Toxic Shock Syndrome Toxin 1)
Enterotoxin

Question 14

What is chickenpox caused by

Answer 14

Varicella Zoster

Question 15

What are the symptoms of varicella zoster infection

Answer 15

Vesicular rash, in groups, concentrated on the face
Lesions in the mouth 
Malaise
Fever
Sore throat

Question 16

What are the two types of fungal infections of the superficial skin

Answer 16

Dermatophytes

Yeasts

Question 17

Give an example of a dermatophyte, state where they grow and describe its structure

Answer 17

E.g. Trichophyton rubrum
Grow in keratin
Long hyphae, grow from tip

Question 18

Give an example of a yeast, state where they grow and describe its structure

Answer 18

E.g. Candida
Grow on warm wet surfaces
single cell and bud

Question 19

What are some types of dermatophytes

Answer 19

Tinea unguium (toenails)
Tinea capitis 
Tinea Manuum (form animals)
Tinea pedis (sold of foot)
Tinea cruris - gential area

Question 20

Give an example of a yeast infection of the skin

Answer 20

Candida Intertrigo

Red rash that is often found in places where sweat is produced.

Question 21

What is sarcoptes scabei

Answer 21

Female mite burrows in the surface of the epidermis (stratum corneum) to cause scabies

Question 22

What is the key sign of scabies

Answer 22

the burrow (4mm squiggle/s-shapes with a black dot (the mite) at one end)

Question 23

Where are burrows from scabies usually found

Answer 23

Breast area, axillary
Umbilical 
Elbows 
Wrists
Genital
Anal area