Skin infections and infestations Flashcards
What is an infection?
The pathological state resulting from the invasion of the body by pathogenic microorganisms
Invasion and multiplication of disease-causing organisms that can lead to local cellular/tissue injury.
Which bacteria normally live on our skin?
Staphylococcus epidermidis
Staph Aureus
Yeast - malassezia furfur
Other aerobic and anaerobic bacteria:
Corynebacterium
Propionbacterium
These should all be in balance
Signs of infection
Erythema - redness Hot Tender Pus - doesn't always mean infection Exudate Fever
Investigations done to check for infection
Skin swab for Microscopy, culture and sensitivities (M,C&S)
If clinically indicated:
Full blood count, ESR
U&Es, LFTs, Calcium, CRP (sign of systemic inflammation)
Skin biopsy
What is Impetigo?
A superficial skin infection. More likely to get it if you have eczema due to barrier dysfunction
Most common bacterial skin infection in children
honey crusting
Causative organisms for impetigo?
Staph A and Strep Pyogenes
Treatment of impetigo
If localised - fusidic acid or Mupirocin (If MRSA - try to restrict this so staph A doesn’t become resistant
If widespread, severe, bullous - flucloxacillin, erythromycin
Name 2 other common skin infections
Cellulitis
Erysipelas
Features of cellulitis and erysipelas
Acute onset, feeling unwell, temperature, systemic = clues to infection
Asymmetrical
Can draw around it to track progression/ response to treatment
Likely causative organisms in cellulitis/erysipelas
Streptococcus pyogenes
Staphylococcus aureus
What is the 1st choice antibiotic in severe cases of cellulitis/erysipelas?
Flucloxacillin + Benzylpenicillin
Which skin problems can occur in the lower legs?
DVT
Venous eczema
Allergic contact dermatitis - dressing etc
Necrotising faciitis - deeper infection, v unwell
If there is a suspected bacterial infection how should you manage it?
Take a swab
Start antibiotics - review after 48 hrs (check skin swab result + response to treatment). Often start broad spectrum then narrow down once sensitivities from swab are back.
If not better in a week consider a different diagnosis (if infection it will usually respond within a week)
Oedema blisters
Often caused by an acute exacerbation of oedema - tissue doesn’t have enough time to compensate
Commonly on dorsum of feet
Often erythematous - red
Can feel hot
Features of Lipodermatosclerosis
Chronic ongoing venous stasis – affects full thickness of skin
Woody/hard leg
If acute can be hot and tender. Often bilateral.
Treatment of lipodermatosclerosis
Treat underlying venous disease
Topical steroids
Name 2 common fungal infections
Tinea - Infection by a Dermatophyte - v rare
Candidiasis
What does the classification of Tinea depend on?
The body site affected
Different names given to Tinea infection with their associated infection site
Ringworm or Tinea corporis if on body
Tinea capitis if on head
Tinea pedis (Athlete’s foot)
Tinea cruris affects the groin
Onychomycosis affects the nails
Treatment of Tinea
Tinea infection of feet, body, hands or groin usually responds to topical treatment
Tinea infection of scalp or nails requires oral antifungals
Names of topical treatments used for selective Tinea infection
Terbinafine or clotrimazole cream
What is Tinea more commonly known as?
Ringworm
What can be sent to the lab to check/test for fungal infection?
Skin scraping - can take 2/3 weeks for result
Common yeast infection that is found in sweaty, warm places on the body?
Candida albicans
