Skin Infections Flashcards
Layers involved:
- Cellulitis
- Furuncle
- Carbuncle
- Erysipelas
Cellulitis: dermis & subcut tissue
Furuncle: folliculitis that extends into subcut tissue (boil)
Carbuncle: multiple furuncles connected by sinus tracts to form a deeper, more complex infection
Erysipelas: raised, sharply demarcated superficial skin infection of the upper dermis and superficial lymphatics
Erysipelas is almost always caused by…
Strep pyogenes (group A strep)
Cellulitis - typical organisms
Strep pyogenes is the MOST COMMON (or other streps) - recurrent, non purulent and spontaneous/rapidly spreading
Staph aureus less commonly causes cellulitis - more associated with penetrating trauma
Purulent cellulitis is typically caused by staph aureus
Specific circumstances & their atypical cellulitis organisms (4)
- Fresh water exposure: aeromonas spp
- Salt water exposure: vibrio spp.
- Chronic liver disease patients; gram negative bacteria
- Immunocompromised: anything
When is IV antibiotic therapy required for cellulitis?
Two or more of the following systemic features:
- Febrile
- Tachycardic
- Tachypnoeic
- Elevated WCC > 12
Patient factors: immunocompromised, diabetes, etc.
If IV therapy used initially, switch early to PO abx if patient is stable
How long do abx take to work for cellulitis?
Can take up to 5 days for local symptoms. Should work on systemic sx quickly. Rash may worsen for 48 hours on antis.
If not improving in 5 days, reconsider dx, look for drainable collection.
Empiric therapy for cellulitis and erysipelas without systemic features.
- Erysipelas, or suspected strep cellulitis (non-purulent, recurrent, spontaneous/rapidly spreading)
- Purulent cellulitis or staph aureus suspected (trauma, ulcer)
- Increased risk of MRSA
- General alternatives if allergic to penicillins
- PenV 500mg PO QID for 5/7
- Dicloxacillin 500mg PO QID for 5/7
OR
Flucloxacillin 500mg PO QID for 5/7 - Bactrim 160+800mg PO BD for 5/7
or
Clindamycin 450mg TDS for 5/7 - If non severe- cephalexin
If severe: clindamycin
Empiric therapy for cellulitis and erysipelas with systemic features
(but not critically unwell)
- Erysipelas, or suspected strep cellulitis (non-purulent, recurrent, spontaneous/rapidly spreading)
- Purulent cellulitis or staph aureus suspected (trauma, ulcer)
- Increased risk of MRSA
- Benzylpenicillin 1.2g IV 6 hourly
- Flucloxacillin 2g IV QID
* If severe allergy to above use vanc* - Vancomycin (dose dependent) IV
When should you cover for MRSA? (7)
- Phx MRSA
- Known MRSA colonidation
- IVDU
- Any severe illness
- Presence of absence of purulent cellulitis
- High rates of MRSA in community
- FHx of MRSA
Bite wound management
- Copious irrigation/debridement
- Prophylactic abx if high risk for infection
> Young/old
> Hands/feet/genitals
> crush injuries, surgical wounds, or puncture wounds, near hardware - Review tetanus status (< 10 years ok unless gross wound, then <5 years)
- Review rabies status if dog/cat
Rabies PEP
Human rabies IVIG + rabies vaccine
IF bitten by
most wild animals (but not rodents)
Unvaccinated pets
Rabid animals
Dog and cat bites - most common organisms
- Strep/staph spp
- Pasteurella spp
- Capnocytophaga canimorsus (more commonly dogs than cats)
Human bites - organisms
Eikenella corrodens
*Consider staph/strep every time
Bird bites - causes
E coli
*Consider staph/strep every time
Equine bites - causes
Actinobacillus spp
*Consider staph/strep every time
