Skin and Soft Tissue Infection (SSTI) – VASP



  • Differential: 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)
    • Think Streptococcus if non-purulent, lymphagitis, or erypsipelas, and Staphylococcus if purulent (i.e. associated with boil or abscess)
  • 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
    • Salt water exposure: Vibrio vulnificus
    • Neutropenia, presence of ecthyma: Gram negatives (Pseudomonas aeruginosa)
    • Immunocompromised: Fungal (candida species, 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: 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 (but should not delay surgical consultation)



  • 5 days for uncomplicated; 10-14 days for more extensive/serious infection, slow improvement, or if immunosuppressed
  • Anti-Staphylococcal antibiotics should be provided 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


MRSA (50% of inpt, 30% of outpt

S. aureus cultures)




- 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



- Cefazolin 2g q8h

- CTX 2g q24h

- Cefazolin 2g q8h

- Nafcillin 2g q4h




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 pain out of proportion to exam, hemorrhagic bullae



    • STAT consult respective surgical service for emergent debridement (generally EGS, but see Wound Care Section of Appendices to confirm)
    • 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)
    • Duration: Not well defined Continue abx at least until HDS and no further surgical debridement is required. Clindamycin may be d/c’d when pt not critically ill and s/p first debridement. Plan must be determined on a case-by-case basis with ID guidance