SSTI Flashcards
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 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
What is the empiric regimen for severe non-purulent SSTIs?
IV Abx for 5-10 days: pip-tazo, cefepime, meropenem
If MRSA risk factors: add IV vancomycin, daptomycin or linezolid
When would improvement in SSTI after initiating antibiotics be expected by?
48-72h
If it takes any longer, reassess indication and/or choice of Abx
Are repeat bacterial cultures required for SSTIs?
No, as long as patient responds
What is mupirocin effective against?
- Highly effective against aerobic gram-positive cocci (esp S. aureus – 2% is bactericidal to it)
- Not effective against enterococci and gram negatives
- Useful for eradication of nasal staphylococcal carriage
What is the pathophysiology of diabetic foot infections?
→ Peripheral neuropathy: ↓pain sensation and altered pain response
→ Motor neuropathy: muscle imbalance
→ Autonomic neuropathy: ↑dryness, cracks and fissures
→ Early atherosclerosis, Peripheral vascular disease, worsened by hyperglycemia and hyperlipidemia
→ Impaired immune response increases susceptibility to infections, worsened by hyperglycemia
Results in ulcer or wound formation, which get colonized by bacteria, bacteria penetrate and proliferate to result in DFI
What is the criteria to consider a DFI to be infected?
Purulent discharge AND
≥2 signs or symptoms of inflammation: erythema, warmth, tenderness, pain, induration (thickening or hardening of the skin)
What are the possible causative pathogens of diabetic foot infections?
- Typically polymicrobial
- Staphylococcus aureus and Streptococcus spp most common
- Gram negatives: particularly if chronic or previously treated w Abx (E.coli, Klebsiella spp, Proteus spp; Pseudomonas aeruginosa less common)
- Anaerobes (Particularly in ischaemic or necrotic wounds; Peptostreptococcus spp, Veillonella spp, Bacteriodes spp)
What features of a DFI would classify it as a mild DFI?
Infection of skin and SC tissue AND
Erythema ≤ 2cm around ulcer AND
No systemic infection signs
What features of a DFI would classify it as a moderate DFI?
Infection of deeper tissue (eg bone, joints) OR
Erythema >2cm around ulcer AND
No systemic infection signs
What features of a DFI would classify it as a severe DFI?
Infection of deeper tissue (eg bone, joints) OR
Erythema >2cm around ulcer AND
Sign(s) of systemic infection
What severities of DFI should cultures be done for?
Moderate to severe - Deep tissue culture after cleansing and before starting antibiotics (if possible)
What organisms need to be covered empirically for mild DFI?
Streptococcus spp + S.aureus
What are the empiric regimen choices for mild DFI?
PO Abx
* Cephalexin
* Cloxacillin
* Clindamycin (for pts allergic to penicillins)
If MRSA risk factors, use PO:
* Co-trimoxazole
* Clindamycin
* Doxycycline
What organisms need to be covered empirically for moderate DFI?
Streptococcus spp + S.aureus + gram negatives
(±P.aeruginosa) + anaerobes
What are the empiric regimen choices for moderate DFI?
Initial IV Abx
* Augmentin
* Cefazolin/Ceftriaxone + Metronidazole
If MRSA risk factors, add IV:
* Vancomycin
* Daptomycin
* Linezolid
What organisms need to be covered empirically for severe DFI?
Streptococcus spp + S.aureus + gram negatives (incl P.aeruginosa) + anaerobes
What are the empiric regimen choices for severe DFI?
Initial IV Abx
* Piperacillin-Tazobactam
* Cefepime + Metro
* Meropenem
* Cipro + Clinda
If MRSA risk factors, add IV:
* Vancomycin
* Daptomycin
* Linezolid
How long should a mild DFI with no bone involvement be treated for?
1-2 weeks
How long should a moderate DFI with no bone involvement be treated for?
1-3 weeks
How long should a severe DFI with no bone involvement be treated for?
2-4 weeks
How long should antibiotics be continued for after an amputation for a DFI?
2-5 days
How long should antibiotics be continued for after a surgery to remove infected bone for a DFI?
1-3 weeks
How long should antibiotics be continued for after a surgery leaving only viable bone for a DFI?
4-6 weeks
How long should antibiotics be continued for after a surgery leaving only dead bone for a DFI?
≥ 3 months
How long should antibiotics be used for a DFI where the bone was involved but no surgery was done?
≥ 3 months
Should antibiotics be continued until complete wound healing?
No
What are the adjunctive measures used in DFI management?
- Wound care: debridement, “off-loading”, dressings that promote healing & control excess exudate
- Foot care: daily inspection, prevent wounds and ulcers
- Optimal glycemic control
What are the risk factors for pressure ulcers?
Generally, if the person is unable to shift/reposition their body to avoid the shearing forces, pressure and friction, they will be at higher risk for pressure ulcers
- Reduced mobility
- Debilitated by severe chronic diseases
- Reduced consciousness
- Sensory and autonomic impairment (esp incontinence)
- Extremes of age
- Malnutrition
Describe the 4 stages of clinical presentation of a pressure ulcer.
Stage 1: Abrasion of epidermis, Irregular area of tissue swelling, No open wound
Stage 2: Extends through the dermis, Open wound
Stage 3: Extends deep into subcutaneous fat, Open sore or ulcer
Stage 4: Involves muscle and bone, Deep sore or ulcer
What are the adjunctive measures for pressure wound management?
→ Debridement of infected or necrotic tissue
→ Local wound care: Normal saline preferred, avoid harsh chemicals
→ Relief of pressure: turn or reposition every 2 hours (also for prevention)
