Dermatology infections Flashcards
Impetigo
Superficial bacterial skin infection usually caused by either staph aureus or strep pyogenes
Can be a primary infection or a complication of an existing skin condition
Impetigo pathophysiology
Direct contact with discharges from the scabs of an infected person
Spread mainly by the hands, but indirect spread via toys, clothing, equipment & environment may occur
Incubation period is between 4-10 days
Impetigo clinical features
Lesions tend to occur on the face, flexures & limbs not covered by clothing
‘Golden’ crusted skin lesions typically found around the mouth
Very contagious
Impetigo mx
Limited, localised disease - hydrogen peroxide 1% cream for those ‘systemically unwell or high risk of complications’
- can give topical antibiotic creams eg. fusidic acid/mupirocin
Extensive disease - PO flucloxacillin/erythromycin
School exclusion - excluded from school until lesions are crusted & healed OR 48 hours after commencing abx treatment
Folliculitis
Inflammation of a hair follicle that results in the formation of papules or pustules
Folliculitis aetiology
Predominantly bacterial infections - staph aureus
Eosinophilic folliculitis - sterile & most commonly arises in the context of immunosuppression (HIV)
Folliculitis clinical features
Presence of papules and pustules
Can appear anywhere on the body except palms of hands & soles of feet
Folliculitis mx
Topical abx with suggested addition of antibacterial soaps
Oral abx in severe cases
Chicken pox
Caused by primary infection with varicella zoster virus
Chicken pox clinical features
Fever initially
Itchy, rash starting on head/trunk before spreading
Initially macular then papular then vesicular
Systemic upset usually mild
Chicken pox mx
Supportive - cool, trim nails, calamine lotion
School exclusion - most infectious period is 1-2 days before rash appears but infectivity continues until all lesions are dry and have crusted over (usually 5 days after)
Immunocompromised patients/newborns - VZIG (if chickenpox develops → IV aciclovir should be considered)
Chicken pox complications
Secondary bacterial infection of the lesions
Pneumonia
Encephalitis
Disseminated haemorrhagic chickenpox
Arthritis, nephritis & pancreatitis → very rarely seen
Shingles
Acute, unilateral, painful blistering rash caused by reactivation of the VZV
Shingles triggers
Emotional stress
Immunosuppression - chemo, high dose steroids
Recent illness or surgery
Skin injury - sunburn, trauma
Shingles clinical features
Prodrome - acute neuralgia, non-specific symptoms, enlarged lymph nodes, 2-3 days long
Infectious phase - rash (unilateral, affecting a single dermatome, initially erythematous & macular → erythematous papules → vesicles/bullae), pain, 7-10 days
Resolution phase - vesicular rash crusts over within 10-12 days of rash onset
Shingles mx
Remind patients they are potentially infectious - avoid immunosuppressed, until veiscles are crusted over
Analgesia - paracetamol & NSAIDs; oral corticosteroids if pain is severe & not responding to above
Antivirals - within 72 hours for the majority of patients -> reduced incidence of post-herpetic neuralgia
- aciclovir, famciclovir or valaciclovir
Shingles complications
Post-herpetic neuralgia
Herpes zoster ophthalmicus - occurs where shingles involves ophthalmic branch of CN V
Ramsey-Hunt syndrome - CN VII affected
Encephalitis
Shingles prevention
Shingles vaccine
- offered to all patients aged 70-79 years
- live-attenuated & given subcutaneously
- SEs - chickenpox, injection site reactions
Viral warts
Cutaneous warts are small, rough growths that are caused by infection of keratinocytes with HPV
Can appear anywhere but are commonly seen on the hands & feet
Usually spread by direct skin-to-skin contact or indirectly via contact with contaminated floors or surfaces
Viral warts mx
Most resolve without treatment
Advice offered on reducing the risk of transmission & limiting personal spread of warts
Treatment considered if wart is painful, unsightly, persistent or requested:
- topical salicylic acid
- cryotherapy
- combination of both
Referral to dermatologist if complex
Molluscum contagiosum
Common skin infection caused by MCV, a member of the Poxviridae family
Majority of cases occur in children, with maximum incidence in preschool children aged 1-4 years
Molluscum contagiosum clinical features
Characteristic pinkish or pearly white papules with a central umbilication
Lesions appear in clusters in areas anywhere on the body (except the palms of the hands & soles of the feet)
Commonly seen on the trunk & in flexures
Molluscum contagiosum mx
Self-care advice - reassure people that molluscum contagiosum is self-limiting, lesions are contagious, exclusion not necessary
Treatment not usually recommended - simple trauma or cryotherapy can be considered
Tinea
Superficial fungal infection of the skin caused by dermatophytes, a group of fungi that invade and grow in dead keratin
Commonly known as ringworm
