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Skin and Soft Tissue Infection (SSTI) - VASP



  • DDx: erysipelas, pyomyositis, necrotizing fasciitis, osteomyelitis, venous stasis, shingles, gout

  • Pathogens: Streptococcus species: Group A (most common), B, C, G, Staphylococcus aureus (including MSSA and MRSA)

    • Non-purulent, lymphangitis, or erysipelas? Think Streptococcus
      • Purulence (abscess or boil)? Think Staphylococcus
  • Unique clinical scenarios and associated organisms/organisms to consider:

    • Dog/cat bite: Pasteurella multicoda, Capnocytophaga canimorsus

    • Human bite: Eikenella corrodens, oral anaerobes, S. aureus

    • Fresh water exposure: Aeromonas hydropholia, Plesiomonas shigelloides

    • Saltwater exposure: Vibrio vulnificus

    • Neutropenia, presence of ecthyma: Gram negatives (Pseudomonas aeruginosa)

    • Immunocompromised: Fungal (Candida spp, Cryptococcus), Nocardia, non-tubercular mycobacteria)

    • Burn patients: Pseudomonas, Acinetobacter, Fusarium


  • Outline border of erythema and obtain urgent surgery consultation if rapid spread of infection, crepitus, air in tissues or pain dramatically out of proportion to exam

  • Blood cultures (BCx): ONLY needed if systemic signs/symptoms of infection or immunocompromised (most pts will not need BCx or imaging)

  • Ultrasound for underlying abscess

  • CT/MRI w/contrast: if necrotizing fasciitis, pyomyositis or osteomyelitis suspected

  • Bilateral lower extremity cellulitis is RARE and warrants further consideration of other non-infectious etiologies

  • Elevation test: if erythema improves after elevating leg above the level of the heart for 1-2 minutes, less likely to be infectious cellulitis


  • Antibiotics for 5 days for uncomplicated; can extend to 10-14 days if little to no improvement, more extensive/serious infection, or if immunosuppressed

  • Typically improvement is not seen until >48 hours of antibiotics, usually longer

  • Provide anti-Staphylococcal antibiotics for purulent cellulitis in addition to I&D, if abscess present

  • Clinical appearance may often appear to worsen initially despite adequate therapy

  • Always elevate the extremity for more rapid clinical improvement!

No Staphylococcus suspected





Cephalexin 500 QID

Amoxicillin 500 TID

Cefadroxil 1g BID

Cephalexin 500 QID

Cefadroxil 1g BID

Dicloxacillin 500 QID

\*Clindamycin 300-450 q6

TMP/SMX 1-2 DS tabs BID

Doxycycline 100 BID

Severe (Inpatient)

Cefazolin 2g q8h

CTX 2g q24h

Cefazolin 2g q8h

Nafcillin 2g q4h

\*Consider for PCN allergy; check antibiogram (VUMC vs VA) for Staph sensitivities; clindamycin should NOT be used for strep coverage

Necrotizing Fasciitis


  • Infection of the deeper soft tissues that causes necrosis along the muscle fascia and overlying subcutaneous fat that is rapidly progressive and lethal if not addressed

  • Clinical cues include rapid spread, pain out of proportion to exam, crepitus and hemorrhagic bullae



    • STAT consult to surgical service for emergent debridement (generally EGS vs ortho)
    • Imaging does NOT rule out necrotizing fasciitis and should not delay these consultations
  • ID consult

    • Blood cultures, but this should not delay antibiotic administration
    • Contact and droplet precautions x first 24h of abx therapy; after this, contact precautions only if draining or contained wounds
    • Vancomycin + either piperacillin-tazobactam 3.375g IV q8h extended infusion OR cefepime 2gm IV q8h + clindamycin 600mg-900mg IV q8h (for antitoxin effects)

Last update: 2022-06-21 19:38:04