Skin infection and infestation Flashcards
What normally protects the skin from infection?
The normal skin microflora and antimicrobial peptides protect skin from infection
Why does skin damage lead to infection?
Micro-organisms can penetrate the skin causing infection
What are the 3 main types of skin infection ?
- Bacterial
- Staphylococcal / Streptococci - Viral
- human papilloma virus / herpes simplex virus - Fungal
- Dermatophytes (Tinea / ringworm)
- Yeasts ( candida)
- Mould (aspergillus)
What are some examples of infestations?
Scabies
Lice
Cutaneous leishmaniasis
What are Erysipelas and cellulitis?
How are they different?
A spreading bacterial infection of the skin
Cellulitis = deep subcutaneous tissue
Erysipelas = an acute superficial form of cellulitis involving dermis and upper subcutaneous tissue
What causes Erysipelas and cellulitis ?
Streptococcus pyogenes
Staphylococcus aureus
What are risk factors for Erysipelas and cellulitis?
immunosuppression
wounds
leg ulcers
toeweb intertrigo (rash in toewebb)
minor skin injury
How does Erysipelas and Cellulitis present?
Look :
signs of inflammation - swelling (tumor), erythema (rubor), warmth (calor), pain (dolor) - may be lymphangitis
Systemic: fever, malaise, rigors (especially erysipeals)
How do you distinguished Erysipelas from cellulitis ?
Erysipelas - well defined, red, raised border
What is the management of Erysipelas and Cellulitis?
Non-pharm:
Supportive - rest, leg elevation, sterile dressings
Pharm:
analgesia
Antibiotics (e.g. flucloxacillin or benzylpenicillin)
What are complications of erysipelas and cellulitis>
Local necrosis
abscess
sepsis
Diagnosis
Describe
Erysipelas
unilateral oedema and erythema with well defined red border.
What is this?
Staphylococcal scalded skin syndrome
Who tends to get Staphylococcal scalded skin syndrome?
Common in infancy and early childhood?
What causes Staphylococcal scalded skin syndrome?
Production of a circulating epidermolytic toxin from phage group II, benzylpenicillin-resistant (coagulase positive) staphylococci
How does Staphylococcal scalded skin syndrome present ?
TIMING, WHERE, APPEARANCE
TIMING:
Few hours - days
WHERE:
worse over face, neck, axillae, groin
APPEARANCE:
Scald - like skin followed by large flaccid bulla
Perioral crusting (typical)
Intraepidermal blistering
painful lesions
eruptions can be localised
How long is recovery for Staphylococcal scalded skin syndrome?
usually 5-7 days
What is the management for Staphylococcal scalded skin syndrome?
Analgesia
Antibiotics (e.g. a systemic penicillinase-resistant penicillin, flucloxacillin, erythromycin or appropriate cephalosporin)
What does this show?
Scabies
How would you describe the lesion of scabies?
Linear burrows - may be tortuous
or
rubbery nodules
What are some associated features with scabies?
Secondary eczema and impetigo
due to scratching- excoriation, infection
What are common sites for scabies?
Sides of fingers, finger webs, wrists, elbows, ankle, feel, nipples, genitals
What is common to get in the history a pt with scabies?
Hx of contact with symptomatic individuals
Pruritus is intense and worse at night
What are some investigations you could do for scabies?
Skin scrape
extraction of mite and view under telescope
What is the management of scabies ?
permethrin 5% is first-line
malathion 0.5% is second-line
Guidance on how to use
pruritus persists for up to 4-6 weeks post eradication
What should you tell your pt with scabies about how to use insecticide ?
apply to all area (including face and scalp)
apply to cool, dry skin
close attention to areas between fingers and toes, under nails, armpit and creases of skin e.g. knee / elbow
Allow to dry and leave for 8-12 hrs for Permethrin and 24 for malathion before washing
Reapply if removed e.g.. hand washing
REPEAT treatment 7 days later
What is the pathophysiology of scabies?
Caused by the mite Sarcoptes scabiei and spread by prolonged skin contact.
The scabies mite burrows into the skin, laying its eggs in the stratum corneum. The intense pruritus associated with scabies is due to a delayed-type IV hypersensitivity reaction to mites/eggs which occurs about 30 days after the initial infection.
