skin infections

Question 1

epidemiology of skin disease

Answer 1

skin disease common, with skin high infection rates in hot humid conditions and poor populations

Question 2

skin disease due to infection in GP vs hospital

Answer 2

more infection % in GP than hospitals

Question 3

prevalence of skin infection by geographical infection

Answer 3

malignant tumours higher in white areas; bacterial, fungal, eczema/dermatitis higher in developing countries

Question 4

describe appearance of Staph. aureus

Answer 4

“bundles of grapes” with a capsule

Question 5

commensal Staph. aureus location (but can become skin infection)

Answer 5

nose, armpits and groin

Question 6

resistant Staph. aureus

Answer 6

MRSA (not worse just harder to treat)

Question 7

4 toxins produced by Staph. aureus and what they cause

Answer 7

panton valentine leucocidin (aggressive soft tissue infection), exfoliative toxin (blisters), TSST-1 (septicaemic features), enterotoxin (causes diarrhoea from contamination of food)

Question 8

besides skin infection, what else can it infect (can go on and cause sepsis)

Answer 8

bone, joint and lung (lung particularly after flu)

Question 9

infection of Staph. aureus in subcorneal layer of epidermis

Answer 9

impetigo (honey-coloured crustic erosion; can produce exfoliative toxin causing splitting of skin to form bullous - blisters containing bacteria which cause puss)

Question 10

infection of Staph. aureus of mouth of hair follicle

Answer 10

folliculitits

Question 11

infection of Staph. aureus of full thickness of epidermis

Answer 11

ecythma (crusted thick lesion with necrotic surface of skin, forming thick scar; caused by infected insect bite)

Question 12

infection of Staph. aureus causing abscess of puss of hair follicle

Answer 12

boil (same as abscess)

Question 13

infection of Staph. aureus causing multiple abscesses of several adjacent hair follicle

Answer 13

carbuncle

Question 14

who is affected by staphylococccal scalded skin syndrome

Answer 14

children under 5 (Staph. aureus causing superficial cleavage of skin)

Question 15

how is staphylococccal scalded skin syndrome treated

Answer 15

antibiotics

Question 16

key features of Staph. auereus

Answer 16

variety of presentations, golden crust, diagnosed by swab, determine which antibiotics it will respond to

Question 17

what is Treponema pallidum

Answer 17

spiral gram -ve bacteria causing syphilis (STD)

Question 18

3 phases of syphilis

Answer 18

primary, secondary, latent syphilis, tertiary syphilis

Question 19

describe primary stage of syphilis

Answer 19

3-8 weeks after inoculation, causing painless ulcer (weepy ulcer on genitals or mouth)

Question 20

describe secondary stage of syphilis

Answer 20

6-12 weeks after inoculation, disseminated infection, generalised rash and lymphadenopathy. with ondyloma lata “warty” regions present too

Question 21

describe tertiary stage of syphilis

Answer 21

years later, causing inflammatory lesions affecting skin, neurological and vascular (can also cause thoracic aneurysms)

Question 22

describe congenital syphilis

Answer 22

acquired perinatally with early and late manifestations

Question 23

what can neurosyphilis cause

Answer 23

dementia

Question 24

pregnancy risks of congenital syphilis

Answer 24

miscarriage, still birth, prematurity, rashes, brain and neurological problems, bone disease

Question 25

diagnosis of primary syphilis

Answer 25

swab, blood test (may or may not be positive)

Question 26

diagnosis of secondary and later syphilis

Answer 26

serology positive; can be made by rash and biopsy (plasma cells present)

Question 27

treatment of syphilis

Answer 27

antibiotics

Question 28

3 members of human herpes virus family ( with latency site of neurones (can reactivate)

Answer 28

HSV-1 (affects around mouth), HSV-2 (affects around genitals), VZV (causes chickenpox and shingles)

Question 29

presentation of herpes simplex (HSV-1 and 2)

Answer 29

vesicular rash (present on mouth, genitals or anywhere else but heal after 2 weeks; with HSV-2 can form crusty blisters); at stress/illness can reactivate

Question 30

eczema risk and what herpes infection causes in patients with eczema

Answer 30

defective barrier function so susceptible to skin infection (with herpes, causes eczema herpeticum)

Question 31

diagnosis of herpes simplex

Answer 31

clinical, swab for PCR

Question 32

treatment of herpes simplex

Answer 32

acyclovir

Question 33

VZV (herpes varicella zoster, chickenpox or shingles) virus incubation

Answer 33

incubation after 1 week: malaise, fever, sore throat, lethargic -> rash with groups of vesicles on erythematous base, concentrated centripetally (face and trunk)

Question 34

complications of VZV

Answer 34

encephalitis (inflammation of brain), pneumonia in elderly

Question 35

describe reactivation of latent VZV

Answer 35

latent in dorsal root ganglion but reactivates in stress/illness (only down one dermatome)

Question 36

symptoms of VZV if effects V1 nerve

Answer 36

facial VZV, causing pain and potentially causing blindness

Question 37

vaccine for chickenpox and shingles

Answer 37

no vaccine for children with chickenpox, vaccine for elderly with shingles

Question 38

2 types of superficial skin fungal infections

Answer 38

dermatophytes (mould), yeasts

Question 39

where are dermatophytes present

Answer 39

grows in keratin so affects skin, hair and nails

Question 40

where are yeast (e.g. candida) present

Answer 40

grow on warm, wet surfaces in body folds

Question 41

what happens to nails in Tinea unguium (dermatophyte)

Answer 41

become yellow and crumbly

Question 42

who are affected by Tinea capitis (dermatophyte)

Answer 42

affect prepubertal children

Question 43

presentation of Tinea capitis (dermatophyte)

Answer 43

crusty lesion on scalp or kerion (boggy mass with pustules) - affects Afrocaribbean children more

Question 44

location of Tinea manuum

Answer 44

affects hands

Question 45

location of Tinea pedis

Answer 45

affects toes

Question 46

location of Tinea cruris

Answer 46

affects skin of inner thigh

Question 47

location of Tinea facei

Answer 47

affects face

Question 48

how can Tinea dermatophytes be transmitted

Answer 48

via pets

Question 49

candida presentation

Answer 49

red, sore, spotty

Question 50

diagnosis of superficial skin fungal infections

Answer 50

scrapings of rash, clippings of nail or pluckings of hair -> cultured/PCR

Question 51

treatment of dermatophytes

Answer 51

terbinafine (cream if skin, tablets if not)

Question 52

treatment of candida

Answer 52

antifungal cream

Question 53

what causes scabies

Answer 53

mites (female burrows into stratum cornea and lays eggs)

Question 54

diagnosis of scabies

Answer 54

look for burrow (4mm long squiggle with black dot (head of mite) at one end)

Question 55

common sites of scabies burrows

Answer 55

finger webs, toe webs, genital area (inflammatory lumps), axilla

Question 56

describe reaction to scabies mites

Answer 56

initial infection is asymptomatic, but after 4 weeks develop immune reaction to cause widespread eczema

Question 57

treatment for scabies

Answer 57

insecticide cream

Question 58

transmission of scabies

Answer 58

direct contact for many minutes

Question 59

consequences of secondary bacterial infections following chronic scabies

Answer 59

cause renal failure due to skin infections of Streptococcus