Acute bacterial skin and skin structure infections

Primary Regimens

• Elevate the involved leg
• Inpatient parenteral therapy:
  • Penicillin G 1 to 2 million units IV q6h
• If history of pencillin skin rash and nothing to suggest IgE-mediated allergic reaction:
  • Cefazolin 1 gm IV q8h or Ceftriaxone 2 gm IV once daily
• If history/evidence of past IgE-mediated allergic reaction (anaphylaxis), then may be forced to use:
  • Vancomycin 15-20 mg/kg IV q8-12h to achieve preferred target AUC24 400-600 μg/mL x hr (see vancomycin AUC dosing calculator); alternative is trough of 15-20 μg/mL
• Linezolid 600 mg IV/po bid
• Treat IV until afebrile; then outpatient Penicillin V-K 500 mg po qid ac and hs for a total of 10 days of therapy.
• Outpatient therapy for less-ill patients:
• Penicillin V-K 500 mg po qid or Amoxicillin 500 mg po q8h OR
• If history of penicillin skin rash and nothing to suggest an IgE-mediated reaction (anaphylaxis, angioneurotic edema):
• Cephalexin 500 mg po qid for 10 days
• If documented past history of IgE-medicated allergic reaction to beta-lactam antibiotics:
• Azithromycin 500 mg po x 1 dose then 250 mg po qd x 4 days OR
• Linezolid 600 mg po bid x 10 days or Tedizolid 200 mg po once daily x 6 days OR
• Delafloxacin 450 mg po every 12 hr x 5-14 days OR
• Omadacycline
  • 200 mg IV (over 60 min) loading dose and then 100 mg (over 30 min) q24 h OR
  • 100 mg IV over 30 min BID on day one and then 100 mg iv over 30 min q24h OR
  • 450 mg PO q24h on days 1 and 2 and then 300 mg PO q24h
• Do not use an older tetracycline for reason of resistance and/or clinical failures.
• If clinically unclear whether infection is due to S. pyogenes or Staph. aureus, get cultures and start empiric therapy: Amoxicillin or Penicillin V-K or Cephalexin for S. pyogenes and TMP/SMX for Staph. aureus (MRSA). See Comment re TMP-SMX.