6- Dermatology (Skin infections: bacterial and fungal) Flashcards
folliculitis background
- Folliculitis means an inflammation or infection of the hair follicles of the skin.
- Due to obstruction in pilosebaceous glands +- infection
causes of folliculitis
- Infection e.g. S.aureus, fungal e.g. Candida spp, herpetic folliculitis (HSV)
- Immune system e.g. eosinophilic folliculitis
- Physical irritation
risk factors folliculitis
Uncut beard
Shaving ‘against the grain’
Thick hair
Excessive sweating
Skin abrasion
presentation of folliculitis
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
management of folliculitis
- 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
cellulitis vs erysipelas
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
which pathogens cause cellulitis and erysipelas
Streptococcous pyogens (group A Beta haemolytic) and staphylococcus aureus
rarely fungal
risk factors for cellulitis
- Previous cellulitis
- Immunosuppression
- Venous insuff
- Elder
- Alcohol dependency
- IV drug use
- Insect bites
- Obesity
- Athletes foot
- Diabetes
presentation of cellulitis
- 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
how can erysipelas be distinguished from cellulitis
distinguished from cellulitis by well-defined, red raised border
investigations for cellulitis
Bloods
- FBC
- CRP
- UEs
- LFTs
- Blood culture
Swabs
- culture fluids
Imaging
- US may be useful if abscess if suspected
Management of cellulitis
- Antibiotics e.g. Fluclox or benzylpenicillin
- Rest and elevate
- NSAIDS
- Clean wound (debride)
- Emollient
- Draw margins
complications of cellulitis
abscess and sepsis
impetigo background
Superficial bacterial skin infection
- Very contagious
- Classified as
o Non-bullous
o Bullous
bullous impetigo
- Epidermolytic toxins released by S.aureus break down proteins that hold skin cells together
- This causes fluid filled vesicles
impetigo causative organisms
- Usually Staphylococcus aureus
- Streptococcus pyogenes
pathophysiology of impetigo
- Occurs when bacteria enter via a break in the skin
- Can be otherwise healthy skin
- Or related to eczema or dermatitis
risk factos for impetigo
- 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.
presentation of nonbullous impetigo
- Around nose or mouth
- ‘golden crust’
- Unsightly
- No systemic symptoms of illness
presentation of bullous impetigo
- 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
Investigations for impetigo
- Swabs of vesicles can confirm diagnosis, bacteria and antibiotic sensitivities
management of nonbullous impetigo
First line:
- Topical fusidic acid
- Hydrogen peroxide 1% cream
Second line (i.e. severe): Flucloxacillin
Stopping the spread of impetigo
- 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
Complications of impetigo
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
superficial fungal infections background
- Common and usually mild infections of superficial layers of the:
o Skin
o Nails
o Hair - Can be serious in immunosuppressed
3 main groups of fungal infections
- Dermatophytes (tinea/ringworm)
- Yeasts e.g. candidiasis, Malassezia furfur
- Moulds e.g. aspergillus
tinea corporis
tinea infection of the trunk and limbs
Presentation
Itchy, circular or annular lesions with a clearly defined, raised and scaly edge is typical
Tinea cruris
tinea infection of the groin and natal cleft
Presentation
Very itchy, similar to tinea corporis
Tinea pedis
Athlete’s foot
Presentation
Moist scaling and fissuring in toewebs, spreading to the sole and dorsal aspect of the foot
Tinea manuum (
tinea infection of the hand
Presentation
Scaling and dryness in the palmar creases
Tinea capitis
scalp ringworm
Presentation
- Patches of broken hair, scaling and inflammation
- bald patches
Tinea unguium
tinea infection of the nail
Presentation
Yellow discolouration, thickened and crumbly nail
Tinea incognito
inappropriate treatment of tinea infection with topical or systemic corticosteroids
Presentation
Ill-defined and less scaly lesions
Candidiasis
- white plaques on mucosal areas
- erythema with satellite lesions in flexures
Pityriasis/Tinea versicolor
infection with Malassezia furfur
Presentation
- Scaly pale brown patches on upper trunk that fail to tan on sun exposure, usually asymptomatic
investigations for fungal skin infections
Investigations
- Skin scraping, hair or nail clippings
- Skin swabs for yeasts
Management of fungal skin infections
- 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
