6- Dermatology (Skin infections: bacterial and fungal)

Question 1

folliculitis background

Answer 1

• Folliculitis means an inflammation or infection of the hair follicles of the skin.
• Due to obstruction in pilosebaceous glands +- infection

Question 2

causes of folliculitis

Answer 2

• Infection e.g. S.aureus, fungal e.g. Candida spp, herpetic folliculitis (HSV)
• Immune system e.g. eosinophilic folliculitis
• Physical irritation

Question 3

risk factors folliculitis

Answer 3

 Uncut beard
 Shaving ‘against the grain’
 Thick hair
 Excessive sweating
 Skin abrasion

Question 4

presentation of folliculitis

Answer 4

It may occur as a relatively trivial irritation - superficial folliculitis, or as a more deep-seated process involving the lower hair follicle

Symptoms
- Rash
- Scratch
- Pustule
- Erythema if deep folliculitis
- Regional draining of lymph nodes should be checked for adenitis ->mild folliculitis
- Folliculitis of eyelast- stye

Question 5

management of folliculitis

Answer 5

• Avoid precipitating factors
• Use moisturizing shaving products
• Shave with the grain
• Good skin hygiene
• Superficial – antiseptics
• Deeper- oral antibiotics e.g. flucloxacillin, erythromycin
• May need surgery

Question 6

cellulitis vs erysipelas

Answer 6

Cellulitis
- Acute, painful and potentially serious infection of the skin and subcutaneous tissues.
- Infection of the dermis and subcut tissue

Erysipelas
- Acute superficial from of cellulitis and involves the dermis and upper subcut tissue

Question 7

which pathogens cause cellulitis and erysipelas

Answer 7

Streptococcous pyogens (group A Beta haemolytic) and staphylococcus aureus

rarely fungal

Question 8

risk factors for cellulitis

Answer 8

• Previous cellulitis
• Immunosuppression
• Venous insuff
• Elder
• Alcohol dependency
• IV drug use
• Insect bites
• Obesity
• Athletes foot
• Diabetes

Question 9

presentation of cellulitis

Answer 9

• Poorly demarcated borders
• Lower limb unilaterally
  o Swelling (tumor)
  o Erythema (rubor)
  o Warmth (calor)
  o Pain (dolor)
• Sometimes precipitating skin lesion
• Blisters and bullae
• Systemic symptoms e.g. fever and malaise
• Red line streaking represents progression of infection to lymphatic system
• Crepitus

Question 10

how can erysipelas be distinguished from cellulitis

Answer 10

distinguished from cellulitis by well-defined, red raised border

Question 11

investigations for cellulitis

Answer 11

Bloods
- FBC
- CRP
- UEs
- LFTs
- Blood culture

Swabs
- culture fluids

Imaging
- US may be useful if abscess if suspected

Question 12

Management of cellulitis

Answer 12

• Antibiotics e.g. Fluclox or benzylpenicillin
• Rest and elevate
• NSAIDS
• Clean wound (debride)
• Emollient
• Draw margins

Question 13

complications of cellulitis

Answer 13

abscess and sepsis

Question 14

impetigo background

Answer 14

Superficial bacterial skin infection
- Very contagious
- Classified as
o Non-bullous
o Bullous

Question 15

bullous impetigo

Answer 15

• Epidermolytic toxins released by S.aureus break down proteins that hold skin cells together
• This causes fluid filled vesicles

Question 16

impetigo causative organisms

Answer 16

• Usually Staphylococcus aureus
• Streptococcus pyogenes

Question 17

pathophysiology of impetigo

Answer 17

• Occurs when bacteria enter via a break in the skin
• Can be otherwise healthy skin
• Or related to eczema or dermatitis

Question 18

risk factos for impetigo

Answer 18

• Age. Impetigo occurs most commonly in children ages 2 to 5.
• Close contact. Impetigo spreads easily within families, in crowded settings, such as schools and child care facilities, and from participating in sports that involve skin-to-skin contact.
• Warm, humid weather. Impetigo infections are more common in warm, humid weather.
• Broken skin The bacteria that cause impetigo often enter the skin through a small cut, insect bite or rash.
• Other health conditions. Children with other skin conditions, such as atopic dermatitis (eczema), are more likely to develop impetigo. Older adults, people with diabetes or people with a weakened immune system are also more likely to get it.

Question 19

presentation of nonbullous impetigo

Answer 19

• Around nose or mouth
• ‘golden crust’
• Unsightly
• No systemic symptoms of illness

Question 20

presentation of bullous impetigo

Answer 20

• More common in neonates and children <2
• Always causes by staphylococcus aureus
• Fluid filled vesicles which grow in size and burst, forming a “golden crust:
• Heal without scaring
• Can be painful and itchy
• Systemic symptoms
• I severe infection called : staphylococcus scalded skin syndrome

Question 21

Investigations for impetigo

Answer 21

• Swabs of vesicles can confirm diagnosis, bacteria and antibiotic sensitivities

Question 22

management of nonbullous impetigo

Answer 22

First line:
- Topical fusidic acid
- Hydrogen peroxide 1% cream

Second line (i.e. severe): Flucloxacillin

Question 23

Stopping the spread of impetigo

Answer 23

• Impetigo is very contagious so children should be kept off school during infection until lesions have healed or had antibiotics for >48 hours

Advice for patient
- to not scratch or touch lesions
- hand hygiene
- avoid sharing face towels and cutlery

Question 24

Complications of impetigo

Answer 24

Impetigo usually responds well to treatment without any long term adverse effects. Rarely there can be complications:
* Cellulitis if the infection gets deeper in the skin
* Sepsis
* Scarring
* Post streptococcal glomerulonephritis
* Staphylococcus scalded skin syndrome
* Scarlet fever

Question 25

superficial fungal infections background

Answer 25

• Common and usually mild infections of superficial layers of the:
  o Skin
  o Nails
  o Hair
• Can be serious in immunosuppressed

Question 26

3 main groups of fungal infections

Answer 26

• Dermatophytes (tinea/ringworm)
• Yeasts e.g. candidiasis, Malassezia furfur
• Moulds e.g. aspergillus

Question 27

tinea corporis

Answer 27

tinea infection of the trunk and limbs

Presentation
Itchy, circular or annular lesions with a clearly defined, raised and scaly edge is typical

Question 28

Tinea cruris

Answer 28

tinea infection of the groin and natal cleft

Presentation
Very itchy, similar to tinea corporis

Question 29

Tinea pedis

Answer 29

Athlete’s foot

Presentation
Moist scaling and fissuring in toewebs, spreading to the sole and dorsal aspect of the foot

Question 30

Tinea manuum (

Answer 30

tinea infection of the hand

Presentation
Scaling and dryness in the palmar creases

Question 31

Tinea capitis

Answer 31

scalp ringworm

Presentation
- Patches of broken hair, scaling and inflammation
- bald patches

Question 32

Tinea unguium

Answer 32

tinea infection of the nail

Presentation
Yellow discolouration, thickened and crumbly nail

Question 33

Tinea incognito

Answer 33

inappropriate treatment of tinea infection with topical or systemic corticosteroids

Presentation
Ill-defined and less scaly lesions

Question 34

Candidiasis

Answer 34

• white plaques on mucosal areas
• erythema with satellite lesions in flexures

Question 35

Pityriasis/Tinea versicolor

Answer 35

infection with Malassezia furfur

Presentation
- Scaly pale brown patches on upper trunk that fail to tan on sun exposure, usually asymptomatic

Question 36

investigations for fungal skin infections

Answer 36

Investigations
- Skin scraping, hair or nail clippings
- Skin swabs for yeasts

Question 37

Management of fungal skin infections

Answer 37

• Treat precipitating factors
  o e.g. underlying immunosuppressive condition
  o Moist environment
• Topical antifungal agents e.g. terbinafine cream
• Oral antifungal e.g. Itraconazole for severe, widespread or nail infection
• Avoid use of topical steroids -> can lead to tinea incognito