Skin Infections and Infestations Flashcards
what is an infection?
The pathological state resulting from the invasion of the body by pathogenic microorganisms
We all have bacteria on the skin, but this does not mean we have an infection - colonisation
what lives on our skin?
Aerobic cocci:
- Staphylococcus epidermidis (1)++
- Staphylococcus aureus* (2)+
Other aerobic and anaerobic bacteria:
- Corynebacterium
- Propionbacterium
Yeasts:
• Malassezia furfur
How can we make a diagnosis of a skin infection?
History
Examination
Investigations
What are the signs of infection?
Erythema
Hot
Tender
Pus
Exudate
Fever
(All of them can be signs of inflammation without signs of infection as well)
How do you determine if a rash is an infection or not?
No systemic symptoms
Rash is not hot, tender and there is no exudate
Therefore atopic eczema
what is Impetigo?
bacterial superficial skin infection
It is the most common bacterial skin infection in children
Impetigo can be ______
bullous
What causes Impetigo?
Staphylococcus aureus, Streptococcus pyogenes
what is the treatment of Impetigo?
Always check local formulary
If localised:
- Fusidic acid 2% cream 3-4 times daily for 5 days
- Mupirocin 2% cream up to 3 times daily for 5 days (if MRSA)
If widespread, severe, bullous:
- Flucloxacillin 500mg oral four times daily for 7 days
- Erythromycin 500mg oral four times daily for 7 days
what is the likely organism causing Cellulitis/Erysipelas?
Hot red swelling
Locally unwell
Temperature
Asymmetrically
Acute
Some thing happened like a insect bite that causes it
- Streptococcus pyogenes
- Staphylococcus aureus
what is the 1st choice antibiotics (if severe) for Cellulitis/Erysipelas?
- Flucloxacillin 1g IV every 6 hours
- plus Benzylpenicillin 1.8g IV every 6 hours
what are some differential diagnosis of Cellulitis/Erysipelas?
Deep vein thrombosis
Venous eczema
Allergic contact dermatitis
Necrotising fasciitis
what is the management and treatment of a bacterial infection?
Take swab
Start antibiotics
Review after ~48hrs:
- check skin swab result
- switch according to sensitivities
If not better in a week:
• consider alternative diagnosis
how do fungal infections usually present?
isolated finding - usually one area of the body
what are the names of fungal infections?
Tinea - Infection by a Dermatophyte
Candidiasis
what does the name of tinea depend on
what site is affected
what are the different names of tinea?
- 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
what is an effect way of investigating a fungal infection?
skin scrapings
what is the treatment of 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
Eczema versus Tinea - how do you tell the difference?
History
Distribution
Skin scrapings
Eczema is extremely common, Tinea corporis or ringworm very rare
Tinea is one area and acute
Eczema is bilateral and chronic
what is a type of yeasts infection?
Candida albicans
what is the treatment of candida?
Nystatin, Miconazole, Ketoconazole cream
what is intertrigo that happens in candida?
Intertrigo is a fancy name for a rash that shows up between the folds of skin. It is a very common skin rash that can crop up throughout life
Most cases are secondary to friction and irritating effect of sweat
Can be due to infection or skin condition
Emollient can often help
what causes hand/finger warts?
Human papilloma virus (HPV)
are warts contagious and what should be done about them?
Warts are contagious but the risk of transmission is low
Children with warts should NOT be excluded from physical activities, but should take care to minimise transmission
Cover the wart with a waterproof plaster when swimming
what is the treatment of warts?
Normally not necessary:
Give patient a leaflet on viral warts
Treatments are not very effective
Wart paints and cryotherapy can stimulate immune system
Warts will go away when patient develops immunity against wart virus
what is Molluscum Contagiosum?
DNA pox virus
Umbilicated papules
May become secondarily infected
Will resolve when patient develops immunity
Shiny and have a dip in them
Central dimple
Common in children with eczema
5% Potassium Hydroxide - not all need treatment, only a few
Herpes Simplex Virus (HSV) is a viral infection - what types are there
Herpes simplex 1 and 2
what deos HSV cause?
Cold sore
Eczema herpeticum
how do you treat HSV?
Treat with aciclovir
what is the name of Herpes Zoster Virus?
Chickenpox
Starts at top of chest and face and spreads down
Once you had it you will be immune to it so cant get it again if immunocompetent
Shingles is your own reaction to chickenpox – cant catch it unless you havnt had chickenpox as a child then you would catch that
where do infestations usually occur on the body?
What is scabies?
Scabies - Sarcoptes scabei
It’s the faeces of the mites that cause the reaction, not the mites themselves
Look for scabetic nodules and burrow in skin
burrows in the skin - black dot is scabies mite
What is Crusted (Norwegian) Scabies?
Got thousands of mites at one time
Highly infectious
Usually also have eosinophilia aswell
what is the treatment of scabies?
Permethrin cream top to toe for 8 hours:
- Two applications 1 week apart
- 30g tube will treat average adult
Treat all in household and close contacts
Explain itch may take 1-4 weeks to settle:
•treat symptomatically with steroid
(topical treatment)
Skin infections are common, but
- Pus doesn’t mean _______
- Positive ____ doesn’t mean infection
Diagnosis is made by _______ and clinical findings
• Supported by ___________
Treat empirically then adjust
Ask for advice if required
Skin infections are common, but
- Pus doesn’t mean infection
- Positive swab doesn’t mean infection
Diagnosis is made by history and clinical findings
• Supported by microbiology
Treat empirically then adjust
Ask for advice if required
