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
What are the recommended antibiotics for moderate cellulitis?
IV cloxacillin, cefazolin
penicillin allergy: clindamycin
What are the recommended antibiotics for severe cellulitis?
Broad-spectrum IV
pip-tazo, cefepime, meropenem
What antibiotic to add to cover water exposure?
ciprofloxacin
What is the recommended treatment duration for cellulitis?
x 5-10d
What is the definition of diabetic foot infection?
Purulent discharge OR >= 2 signs of inflammation
Warmth
Induration
Pain
Erythema
Tenderness
What are the expected pathogens of DFI?
- s. aureus, streptococci
- gram neg: e. coli, klebsiella, proteus, pseudomonas (less common)
- anaerobe: peptostreptococcus, veillonella, bacteroides
How to differentiate between mild, moderate and severe DFI?
mild: erythema <= 2cm around wound, no systemic symptoms
moderate: erythema > 2cm around wound, no systemic symptoms
severe: erythema > 2cm around wound, systemic symptoms
What pathogens to cover for mild DFI?
s. aureus, streptococci
What antibiotics to use for mild DFI?
PO cloxacillin, cephalexin, clindamycin (pen allergy)
What pathogens to cover for moderate DFI?
s. aureus, streptococci, gram neg (klebsiella, e. coli, proteus)
anaerobe: peptostreptococcus, veillonella, bacteroides
x pseudomonas
What antibiotics to use for moderate DFI?
IV amox-clav
IV cefazolin / ceftriazone + metronidazole
What pathogens to cover for severe DFI?
s. aureus, streptococci, gram neg (klebsiella, e. coli, proteus, pseudomonas)
anaerobe: peptostreptococcus, veillonella, bacteroides
What antibiotics to use for severe DFI?
pip-tazo, meropenem, ciprofloxacin + clindamycin, cefepime + metronidazole
What antibiotics to add in mild, moderate, and severe DFI with MSRA risk?
mild: PO bactrim, doxycycline, clindamycin
moderate / severe: IV vancomycin, daptomycin, linezolid
What is the recommended duration of treatment of mild, moderate, and severe DFI with no bone involvement?
mild: 1-2w
moderate: 1-3w
severe: 2-4w
What is the recommended duration of treatment of mild, moderate, and severe DFI with bone involvement (surgery - all infection removed / residual infected tissue / residual infected bone; no surgery - residual dead bone)?
surgery
- all infection removed: 2-5d
- residual infected tissue: 1-3w
- residual infected bone: 4-6w
no surgery, residual dead bone: >= 3m
What are the monitoring points for SSTI?
Improvement in 48-72H, no progression of lesion / complications
What are the 3 adjunctive measures in the management of pressure ulcers?
- Wound care with normal saline
- Debridement
- Pressure relief by repositioning every 2 hours
What is the criteria for infection of pressure ulcers?
Purulent discharge OR >= 2 signs of inflammation
Warmth
Induration
Pain
Erythema
Tenderness
What are the pathogens implicated in pressure ulcer infections?
s. aureus, streptococci
gram neg: e. coli, klebsiella, proteus, pseudomonas (less common)
anaerobe: peptostreptococcus, viellonella, bacteroides
