Skin and Soft Tissue Infections Flashcards
What are the normal protective mechanisms against skin infections?
- normal, intact skin
- shedding of keratocytes and skin microbiota
- sebaceous secretions inhibit growth
- commensal skin microbiome prevents colonisation and overgrowth of more pathogenic strains
What are the 3 risk factors for SSTI?
- disruption of skin barrier
- conditions that predispose to infection
- history of cellulitis
Where should wound culture be taken?
Deep inside wound / base of closed abscess / curettage
What bacteria usually cause impetigo?
Group A strep (s. pyogenes) and s. aureus
What bacteria usually cause ecthyma?
Group A strep (s. pyogenes)
What is the first line treatment for mild impetigo with limited lesions?
Topical mupirocin BD x 5d
What is the first-line empiric regimen for ecthyma / impetigo with multiple lesions?
PO Cloxacillin / cephalexin
pen allergy: PO clindamycin
duration x 7d
What is the culture directed regimen for ecthyma / impetigo with multiple lesions caused by s. pyogenes?
PO penicillin V / PO amoxicillin x 7d
What is the culture directed regimen for ecthyma / impetigo with multiple lesions caused by s. aureus?
PO cloxacillin / PO cephalexin x 7d
Define Healthcare-associated MRSA infection
MRSA infection that occurs >48H after hospitalisation or outside hospital within 12 months of exposure to healthcare
What are the risk factors of HA-MRSA?
Prior antibiotic use, recent hospitalisation, prolonged hospitalisation, intensive care, hemodialysis, MRSA colonisation, contact with MRSA colonised individuals
Which SSTIs are purulent?
Furuncle, Carbuncles, skin abscess
What are the common pathogens implicated in purulent SSTI?
s. aureus, some beta hemolytic strep
What other pathogens must be considered if the purulent SSTI is a skin abscess near GI?
Gram negative and anaerobic bacteria
What is the treatment option for mild purulent SSTI?
Incision and drainage, warm compress to promote drainage
What is the recommended regimen for moderate purulent SSTI?
Incision and drainage + PO cloxacillin / PO cephalexin / PO clindamycin (pen allergy)
What is the recommended regimen for severe purulent SSTI?
IV cloxacillin / IV cefazolin / IV clindamycin / IV vancomycin
What antibiotics should be included in a patient with purulent SSTI with MRSA risk factors?
PO: Bactrim / Clindamycin / Doxycycline
IV: Vancomycin / Daptomycin / Linezolid / Ceftaroline (too broad)
What antibiotics should be included in a patient with purulent SSTI near GI?
Amox-clav (gram-neg and anaerobe coverage)
What is the recommended treatment duration for purulent SSTU?
x 5-10d
What are the pathogens implicated in cellulitis and erysipelas?
s. pyogenes, s. aureus less common
What are the pathogens implicated in cellulitis with water exposure?
Aeromonas (fresh water), vibrio (sea water), pseudomonas
How is mild, moderate, and severe cellulitis classified?
mild: no systemic symptoms
moderate: systemic symptoms, some purulence
severe: systemic symptoms, failed oral therapy, immunocompromised
What are the recommended antibiotics for mild cellulitis?
PO penicillin V, cloxacillin, cephalexin
penicillin allergy: clindamycin