Skin Infections and Infestations Flashcards
What is an infection?
Pathological state resulting from invasion of the body by pathogenic microorganisms
What lives on the skin?
Aerobic cocci - staphylococcus epidermidis and staphylococcus aureus
Corynebacterium and Propionibacterium
Yeats - Malassezia furfur
What are the signs of an infection?
Erythema, hot, tender, pus, exudate and fever
Does purulent skin problem mean there is infection?
No - can have sterile purulent
Signs of no infection - apyrexial, no rigors, long standing rash and no growth of pathogens on swab
What is impetigo?
Superficial skin infection
Most common bacterial skin infection in children
Can be bullous
Staph. aureus and strept pyogenes
What is the treatment for impetigo 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)
What is the treatment for impetigo if widespread, severe or bullous?
Flucloxacillin 500mg oral 4 times daily for 7 days
Erythromycin 500mg oral 4 times daily for 7 days
What is the likely organism for cellulitis/ erysipelas?
Streptococcus pyogenes and staphylococcus aureus
What is the first choice antibiotic for cellulitis/ erysipelas?
Flucloxacillin 1g IV every 6hrs plus Benzylpenicillin 1.8g IV every 6hrs
What are some differential diagnosis for bacterial skin infections?
Deep vein thrombosis
Venous eczema
Allergic contact dermatitis
Necrotising fasciitis
What is the investigation and plan for bacterial infection?
Take swab - start antibiotics
Review after 48hrs - check skin swab result and switch according to sensitivities
If not better in a week then consider alternative diagnosis
Describe oedema blisters
Acute exacerbation of oedema can cause blisters to appear
Dorsum of feet
Often erythematous and can feel hot
Describe lipodermatosclerosis
If acute then can be hot and tender
Look for signs of venous disease and bilateral
Due to poor circulation in legs
Scarring and discolouration - hemosiderin depositions
What is the treatment for lipodermatosclerosis?
Treat underlying venous disease
Topical steroids
What are types of fungal infections?
Tinea (mould) - infection by dermatophyte
Candidiasis (yeast)
What are some different types of tinea?
Named by site affected
Ringworm or Tinea corporis if on body
Tinea capitis - head
Tinea pedis - athletes foot
Tinea cruris - groin
Onychomycosis - nails
What is tinea manuum?
Fungal infection of the head
One hand suggests that the source is elsewhere
Hyper-linearity
How is fungal infection diagnosed?
Skin scrapings
What is the treatment for tinea?
Feet, body, hands or groin usually respond to topical treatment - Terbinafine or clotrimazole cream
Scalp or nails - oral anti-fungal
Check and treat other family members
How is eczema differentiated between tinea?
History, distribution - eczema usually symmetrical and is extremely common, skin scrapings and tinea corporis or ringworm are rare
What is a type of yeast causing fungal infection?
Candida albicans - likes warm and moist places like the flexures/ folds of skin
What is the treatment of candida?
Nystatin, Miconazole and Ketoconazole cream
Describe intertrigo
Superficial rash in folds of persons body - caused by yeast
Can be due to infection or skin condition
Most cases are secondary to friction and irritating effect of sweat
Emollient can often help
What is the general advice for viral warts?
Contagious but the risk of transmission is low - children should not be excluded from activities but take care to minimise transmission
What is the treatment for viral warts?
Normally not necessary
Wart paints and cryotherapy can stimulate immune system
Warts will go away when patient develops immunity against wart virus
What is a cause of viral warts?
Human papilloma virus
Describe molluscum contagiosum
DNA pox virus
Umbilicated papules
May become secondary infected
Will resolve when patient develops immunity
What can help with treatment for molluscum contagiosum?
5% potassium hydroxide - can help give inflammatory response to help start immune system
Describe herpes simplex virus (HSV)
Herpes simplex 1 and 2
Cold sores for type 1 and genitals affected in type 2
Eczema herpeticum can give widespread infections
What is the treatment for HSV?
Aciclovir
What is the presentation of herpes zoster virus?
Chicken pox in children - cranial to caudal spread and self-limiting
Shingles is the reactivation in adults
What is a type of infestation?
Scabies - mites in human infection
Sarcoptes scabei
Where about on body does scabies appear?
Web spaces, wrists, nipples, ankles and genitals
What is a burrow and how is it good for diagnosis of scabies?
Burrow is mite path
For diagnosis a marker pen is drawn over bump and then wiped off - if burrow then ink will be there
What is crusted scabies?
Thousands of mites - highly infectious
Hyper infestation which can occur in the immunocompromised
How is scabies diagnosed?
Biopsy and have crust removed
What is the treatment for scabies?
Permethrin cream top to toe for 8 hours - two applications 1 week apart
Oral ivermectin can be used - not in UK
Explain that itch may take 1-4 weeks to settle - treat symptomatically with steroids
Does a positive swab always mean infection?
No - if eczema broken skin can hold bacteria
