SSTI

Question 1

site of infections

Answer 1

Epidermis: Impetigo
Dermis: Ecthyma(pustular form of impetigo) , Erysipelas
Hair follicles: Furuncles, Carbuncles
SC fat: Cellulitis
Fascia: Necrotizing fasciitis → fast disease progression (disproportionate pain from infected site)
Muscles: myositis

Question 2

risk factors for SSTIs

Answer 2

(impaired skin barrier function)
Age (v yong and old)
Infection
Physical damage (pressure, friction, lacerations)
Physical environment - contact with moisture (too much/little)
Ischaemia - lack of perfusion
Diseases - DM, cirrhosis, Neutropenia, HIV, transplant
Drugs (immunosup, SGLT2i)
pH
Excessive soap/detergent use
(SSTI)
Disruption of skin barrier
Traumatic: lacerations
Non traumatic: ulcers, tinea pedis
Impaired venous and lymphatic drainage (Saphenous venectomy, obesity, chronic venous insufficiency
Peripheral artery disease
Cellulitis Hx

Question 3

non-rx treatment for SSTI

Answer 3

Manage RF and treat cause
1. Maintain skin integrity
2. Good foot care for diabetic
3. Ensure rest and limb elevation (drainage of edema/inflam substances)
4. Treat underlying conditions (tinea pedis, skin dryness, limb edema)

Question 4

Abx for impetigo/ecthyma

Answer 4

impetigo (mild, limited lesions) Topical Mupirocin BD x5d
Ecthyma (multiple lesions) x7d(mild), 10-14d(mod-sev)
Empiric PO cephalexin or cloxacillin or (penicillin-allergy) Clindamycin
(S. pyogenes): PO penicillin V, amoxicillin
(MSSA): PO cephalexin or cloxacillin

Question 5

Abx for non-purulent skin infections

Answer 5

Non-purulent: mostly beta-hemolytic Streptococcus (grp A strep), water exposure (Aeromonas[freshwater/hot tub], Vibrio vulnificus[seawater], Pseudomonas)
- (mild [only cover S. pyogenes]) PO Abx: Penicillin V/ Cephalexin/ Cloxacillin/ Clindamycin
- (mod [systemic + purulence(include MSSA)]) IV Abx: Cefazolin/ Cloxacillin/ Clindamycin
- (sev [systemic + failed PO + immunocompromised]) IV Abx: Piptazo/ cefepime/ meropenem + (MRSA) IV Vancomycin/ Daptomycin/ Linezolid x5-10d,14d(immunocompromised)

Question 6

Abx for purulent skin infections

Answer 6

(mild) I&D + warm compress

(mod w systemic symptoms): I&D + PO Abx(Cloxacillin/ cephalexin/ clindamycin(penicillin allergy)

(sev) I&D + IV Abx (Cloxacillin/ cefazolin/ clindamycin/ vancomycin)

Empiric (MRSA) x5-10d
PO Co-trimaxozole/ doxycycline/ clindamycin
IV vancomycin/ daptomycin/ linezolid/ ceftaroline(dn use cos broad spectrum)

Empiric (GN, anaerobe): x5-10d
(mild) PO Amoxicillin-clavulanate
(mod) piptazo
(sev) carbapenem (ESBL)

Question 7

monitoring for SSTIs

Answer 7

Monitoring:
Improvement in 48-72h aft initiation
ADR
No progression of lesion/complications
Switch to PO if better
If fail to respond clinically within 2-3d, reassess indication → repeat culture

Question 8

Sx of DFI

Answer 8

Infected: purulent discharge or >= 2 signs of Sx: Erythema, Warmth, tenderness, pain, induration (thickening and hardening of soft tissues)

Question 9

non-Rx for DFI

Answer 9

Wound care (debridement, “off-loading”, dressing to control excess exudate)
Foot care (daily inspection, prevent wounds and ulcers)
Optimal glycemic control

Question 10

non-Rx for pressure sores

Answer 10

Debridement of infected/necrotic tissue
Local wound care (normal saline, avoid harsh chemicals)
Pressure relief (turn/reposition every 2h, use water/air bed)

Question 11

Abx for DFI

Answer 11

mild: PO Abx
cephalexin
cloxacillin
clindamycin
(MRSA) PO cotrimoxazole, clindamycin, doxycyline

mod: IV
amox-clav
cefazolin/ceftriaxone + metronidazole
(MRSA) vancomycin, daptomycin, linezolid

sev: IV
piptazo
cefepime +metronidazole
meropenem
cipro +clindamycin
(MRSA) vancomycin, daptomycin, linezolid

Duration of trx:
no bone involved: 1-2w, 1-3w, 2-4w
bone involved:
surgery, all removed: 2-5d
surgery, residual inf soft tissue: 1-3w
surgery residual viable bone: 4-6w
no surgey: >3m