Management of SSTI Flashcards
(54 cards)
How does the skin serve as a physical barrier to infection?
→ Protects against mechanical injury, UV irradiation, microbial and chemical assaults
→ Prevents excessive water loss and desiccation
How does the skin serve as a chemical barrier to infection?
→ Skin pH is maintained at 4-5 by producing free fatty acids from phospholipids – keeps bacteria and Candida low, and regulates desquamation (keeps transient bacteria to a minimum)
→ Resident flora help to keep transient bacteria to a minimum as well
How does the skin serve as an immunological barrier?
→ Forms part of the innate immunity – physical barrier, antimicrobial peptides (AMP), cytokines, cells containing pattern-recognition receptors
→ AMPs are produced by the skin during inflammation process – directly kill pathogens, promotes wound healing, initiates adaptive immune response, controls inflammation
What are the risk factors for SSTIs?
- Traumatic disruptions of the skin: Lacerations, recent surgery, burns, abrasions, crush injuries, open fractures, injection drug use, human/animal/insect bites
- Nontraumatic disruptions of the skin: ulcers, tinea pedis, dermatitis, toe web intertrigo, chemical irritants
- Impaired venous and lymphatic drainage (Saphenous venectomy, Obesity, Chronic venous insufficiency)
- Peripheral artery disease
- Diabetes
- Cirrhosis
- Neutropenia
- HIV
- Transplantation & immunosuppressive meds
- Hx of any SSTI - prev use of antibiotics for it
How can SSTIs be prevented?
- Focus on managing predisposing risk factors
- Good care to maintain skin integrity eg good wound care, treating tinea pedis, preventing dry cracked skin, good foot care for DM patients to prevent wounds and ulcers
- Predisposing factors should be identified and treated at the time of initial diagnosis to decrease recurrence
- Copiously irrigate acute traumatic wounds, remove foreign objects, and debride devitalised tissues
When are cultures required for SSTIs?
Once patient has systemic symptoms (moderate severity or worse)
Where should a skin wound culture be taken from?
- From deep in the wound after cleaning the surface
- From base of a closed abscess, where bacteria grows
- By curettage, rather than wound swab or irrigation
What are the likely pathogens to be found in impetigo?
Staphylococci or streptococci
Bullous form: toxin-producing strains of S. aureus
What are the likely pathogens to be found in ecthyma?
Most frequently caused by Group A streptococci (partial haemolysis)
What are the likely pathogens to be found in non-purulent skin lesions (cellulitis, erysipelas)?
Mainly beta-haemolytic streptococcus, usually group A (eg Streptococcus pyogenes)
S. aureus is much less frequently
Other less common pathogens based on exposure and risk factors – Aeromonas, Vibrio vulnificus, Pseudomonas w water exposure
What are the likely pathogens to be found in purulent skin lesions (cellulitis, erysipelas)?
Mainly by S. aureus
Some beta-haemolytic streptococcus
Isolation of multiple organisms (incl gram negatives and anaerobes) more common in patients w skin abscess involving the perioral, perirectal or vulvovaginal areas
What is the empiric regimen for mild impetigo?
TOP Mupirocin BD x 5/7
What are the empiric regimens for impetigo or ecthyma, when there are multiple lesions?
PO cephalexin or cloxacillin
PO clindamycin
Both used to cover MSSA and Streptococci, for 7 days
What is the culture-directed therapy choice for impetigo or ecthyma that tests positive for Streptococcus pyogenes?
PO Penicillin V or amoxicillin for 7/7
What is the culture-directed therapy choice for impetigo or ecthyma that tests positive for MSSA?
PO cephalexin or cloxacillin for 7/7
When are antibiotics indicated for purulent SSTIs?
- Unable to drain completely
- Lack of response to I&D
- Extensive disease involving several sites
- Extremes of age (weak immune system)
- Immunosuppressed (chemo, transplant etc)
- Severe disease
- Signs of systemic illness
What is the treatment choice for mild purulent lesions?
I&D or warm compress to promote drainage
What is the treatment choices for moderate purulent lesions?
I&D + PO Abx (cloxacillin or cephalexin or clindamycin) for 5-10 days
Clindamycin is used if patient has penicillin allergy
What are the treatment choices for severe purulent lesions?
I&D + IV Abx (cloxacillin or cefazolin or clindamycin or vancomycin) for 5-10 days
Vancomycin used only if patient has allergy to the other 3, or has MRSA risk factors
What are the outpatient treatment choices for potential MRSA SSTIs?
PO Clindamycin, Doxycycline or Co-trimoxazole for 5-10 days
What are the inpatient treatment choices for potential MRSA SSTIs?
IV Vancomycin, Linezolid, Daptomycin for 5-10 days (Vancomycin usually used, other 2 are expensive)
What is the empiric regimen for SSTIs likely caused by gram negatives and/or anaerobes?
PO augmentin for 5-10 days
(if there is risk of resistance, can consider pip-tazo)
What is the empiric regimen for mild non-purulent SSTIs?
PO Penicillin V, cephalexin, cloxacillin for 5-10 days - mainly cover Streptococcus pyogenes
Can use clindamycin if allergic to penicillin
What is the empiric regimen for moderate non-purulent SSTIs?
IV Cefazolin or cloxacillin for 5-10 - to cover S.pyogenes and MSSA
Can use clindamycin if allergic to penicillin
