Skin Infections and Infestations Flashcards
What lives on our skin?
Aerobic cocci
- Staphylococcus epidermis
- Staphylococcus aureus
Other aerobic and anaerobic bacteria
- Cornebacterium
- Propionbacterium
Yeasts
-Malassezia furfur
What are the signs of an infection?
Erythema Hot Tender Pus Exudate Fever
What is pustulous psoriasis?
Generalised pustular psoriasis is a rare and serious skin disorder that presents with flares of widespread sterile pustules on a background of red and tender skin.
What are good investigations in dermatology?
Skin swab for microscopy, culture and sensitivities (M, C and S)
Skin biopsy
Scrapes of skin
What is Impetigo?
Impetigo is a contagious superficial skin infection
Most common bacterial skin infection in children
Classical golden crusting, honeycomb sort of look
What are the causes of impetigo?
Staphylococcus aureus
Streptococcus pyogenes
What is the treatment for localised impetigo?
Fusidic acid 2% cream 3-4 times daily for 5 days
Mupirocin 2% cream up to 3 times daily for 5 days
Why does the lecturer prefer Mupirocin treatment for impetigo?
Staph aureus gets resistant to Fusidic acid very quickly so better off with mupirocin
What is the treatment for widespread, severe, bullous impetigo?
Flucloxacin 500mg oral 4 times a day for 7 days
Erythromycin 500mg oral 4 times a day for 7 days
What is Erysipelas?
Erysipelas is a superficial form of cellulitis, a potentially serious bacterial infection affecting the skin.
Erysipelas affects the upper dermis and extends into the superficial cutaneous lymphatics. It is also known as St. Anthony’s fire, with reference to the intense rash associated with it.
Patient usually systemically unwell
What are the likely causes of Cellulitis/Erysipelas?
Streptococcus pyogenes
Staphylococcus aureus
What is the 1st choice antibiotic in cellulitis/ Erysipelas?
Benzylpenicillin 1.8g IV every 6 hours
-Better for streptococci
Flucloxacillin 1g IV every 6 hours plus benzylpenicillin
-If patient is really sick
What is the differential diagnosis for cellulitis?
Deep vein thrombosis
Venous eczema
Allergic contact dermatitis
Necrotising fasciitis
What is the general rule for managing bacterial infection?
Take swab
Start antibiotics
Review after around 48hours
- Check skin swab result
- Switch according to sensitivities
If not better in a week
-consider alternative diagnosis
What are oedema blisters?
Acute exacerbation of oedema
Occur on dorsum of feet
Often erythematous
Can feel hot
What is lipodermatosclerosis?
Lipodermatosclerosis refers to a skin change of the lower legs that often occurs in patients who have venous insufficiency. It is a type of panniculitis (inflammation of subcutaneous fat). Two-thirds of affected patients are obese.
What are the features of legs with lipodermatosclerosis?
- Skin induration (hardening)
- Increased pigmentation
- Swelling
- Redness
- “Inverted champagne bottle” or “bowling pin” appearance
- Lipodermatosclerosis has also been called hypodermitis sclerodermiformis and sclerosing panniculitis.
If acute what features may lipodermatosclerosis have in addition to its characteristic features?
Hot and tender
Look for signs of venous disease
BILATERAL
What is the treatment for lipodermatosclerosis?
Treat underlying venous disease
Topical steroids
What is included in fungal infections?
Tinea
-Infection by a dermatophyte
Candidiasis
How can you spot fungal infections?
Classically cause a ringworm appearance
- Advancing erythematous ring
- Sometimes scaling around the edges
- Pretty much fungal until proven otherwise
How are tinea infections named?
Name depends on site affected
- Ringworm or Tinea corporis if on body
- Tinea capatis (head)
- Tinea fasciei (face)
- Tinea pedis (Athlete’s foot)
- Tinea cruris (groin)
- Onychomycosis (nails)
What is the best way to diagnose fungal infections?
Scrape the edge of the infection
Not the middle as all the dead infection will be here (infection moves outward
What is the treatment for tinea?
Tinea infection of feet, body, hands or groin usually responds to topical treatment
-Terbinafine or clotrimazole cream
Tinea infection of scalp or nails requires oral antifungals
Check and treat other family members
What is the better topical tinea treatment?
Terbinafine is much better at killing dermatophytes.
If unsure diagnostically clotrimazole is better
What is the difference between eczema and tinea?
History
Distribution
Skin scrapings
Ezcema is extremely common, Tinea corporis or singworm very rare
What yeasts may cause infection
Candida albicans
What kind of conditions do yeast infections like candida albicans like?
Warm, moist places
under folds of fat, vagina etc
What is the treatment for candida infection?
Nystatin
-Will kill yeast (not fungi)
Miconazole
-Will kill yeast and fungi
Ketoconazole cream
-Will kill yeast and fungi
What is intertigo?
Intertrigo describes a rash in the flexures or body folds, such as behind the ears, in the folds of the neck, axillae, under a protruding abdomen, in the groin, between the buttocks, in the finger webs or toe spaces.
What are the causes of intertigo?
Most cases are secondary to friction and irritating effect of sweat.
Can be due to infection or skin condition
What is the treatment for intertigo?
Emollient can often help
Best way is to lose weight
What are viral warts?
Warts are very common non-cancerous growths of the skin caused by infection with human papillomavirus (HPV). More than 100 HPV subtypes are known, giving rise to a variety of presentations.
A viral wart on the sole of the foot is also called a verruca, and warty lesions are often described as verrucous.
How many HPV actually cause viral warts?
Only really about 4 main types.
Usually dont go to lab for diagnosis
What advice should you give physically active patients with warts?
Children with warts should NOT be excluded from physical activities, but should take care to minimise transmission
Cover wart with waterproof plaster when swimming
How contagious are warts?
Warts are contagious but the risk of transmission is low.
What is the treatment for warts?
Not normally necessary
- Not very effective
- Will go away when patient evelops immunity against wart virus
Give patient a leaflet on viral warts
What is Molluscum Contagiosum?
Molluscum contagiosum (MC) is a viral infection of the skin or occasionally of the mucous membranes, sometimes called water warts.
It is caused by a DNA poxvirus
How may Herpes Simplex Virus (HSV) present in someone immunosupressed or atopic?
Widespread virus symptoms and can be quite ill
Eczema herpeticum
Treat with aciclovir
What is the pathogenesis of herpes zoster virus?
Same type of behaviour as herpes simplex virus
First time your infected -> chicken pox -> tracks up nerve to dorsal root ganglion and stays dormant
Sometimes can track down nerve to infect single dermatome -> Shingles
What is Scabies?
Scabies, known as the seven-year itch, is a contagious skin infestation by the mite Sarcoptes scabiei.
The most common symptoms are severe itchiness and a pimple-like rash.
Occasionally tiny burrows may be seen in the skin.
How long must you have contact with someone to contract scabies?
About 1 min
Only caught from people close to you
How do you diagnose scabies?
Finding a burrow is diagnostic
What are good places to find burrows (people to get itchy) in scabies?
Nipples Umbilicus Wrists Genitalia Back of ankle Plantar of foot
What is the pathogenesis of scabies?
Mite burrows into skin
Feces build up and after a couple of weeks reaction occurs -> itching
If infected again allergy is already there so symptoms only after a day
What is the treatment for scabies?
Permethrin cream top to toe (literally everywhere)
- Leave for 8 hours
- Second application a week later
- 30g tube for average adult
Treat all in household and close contact
Explain itch may take 1-4 weeks to settle
-treat symptomatically with steroid
