Skin & Soft Tissue Infections:

What organism is suspected in purulent SSTI? Non-purulent SSTI?

Purulent: Staph aureus

Nonpurulent: Usually strep but can be staph

What patients should you consider for getting a culture in SSTI?

Necrotizing infection or patients with persistent, recurrent fever and neutropenia

In a previously healthy patient, what are the likely organisms? How is this differing among people who inject drugs? History of diabetes?

Prev healthy: CA-MRSA, MSSA, GAS

Inject: CA-MRSA, MSSA, GAS, Gram (-), Anaerobes

Diabetics: P. aeruginosa, HA-MRSA, MSSA, Gram (-)

What makes mild, moderate, and severe SSTI different?

Mild: Typical infx, systemic sx absent

Moderate: Typical infx, systemic sx present

Severe: Systemic and severe sx present, failed oral therapy

Does a mild purulent SSTI require antibiotics?

No only incision and drainage

What are the empiric regimens for Moderate and Severe purulent SSTI? What patient / infection factors might be present where an option may not be ideal

Moderate: Bactrim* or Doxycycline

Severe: Vanco, Dapto, Linezolid, or Ceftaroline

**Bactrim should always be combined with incision and drainage- DO NOT USE if incision can't be drained

Should we use Clindamycin for MRSA?

Clinfamycin not recommended for MRSA, not first line for MSSA, due to inducible resistance

How long do you treat purulent SSTI?

5-10 days (shorter the better)

If there is a risk of Gram-negative +/- anaerobe purulent SSTI, what antibiotics should be used?

1. PCN/B-lactamase inhibitor (ex: Amp/Sulbactam) OR 

2. 2nd/3rd gen Cephalosporin (ex: Cefuroxime, Ceftriaxone) → only once daily dosing easier for pt 

Does a mild non-purulent SSTI require antibiotics?

• Yes - options are

  • PCN → if highly suspect strep as cause 

  • Cephalosporin → once daily dosing easiest for pt 

  • Dicloxacillin

  • Clindamycin

What are the empiric regimens for non-purulent SSTI based on severity? What patient / infection factors might be present where an option may not be ideal?

Mild: PO- Penicillin, Cephalosporin, Dicloxacillin or Clindaymycin
Moderate: IV- Penicllin, Ceftriazone, Cefazolin, Clindamycin
Severe: emergency surgery+ Vanco+ Pip/tazo

For necrotizing infections, what are the organisms involved in monomicrobial infections? What are the treatments? Why use clindamycin?

• Strep pyogenes and Clostridial sp 

• Txt with PCN + Clinda 
  
  Clinda reduces release of toxins 

For necrotizing infections, what are the organisms involved in polymicrobial infection? What is the antibiotic regimen?

Txt with Vanco + Pip/Tazo

What is the organism is most found in lymphangitis? What is the initial and step-down therapy?

S. pyogenes

Initial: IV PCN-G 1-2 million units q4-6 hrs for 2-3 days

Step-down: PO PCN-V for 10 days total

If PCN allergy use clinda

What is the causative organism in erysipelas? How are treatments for mild and severe different? B-hemolytic strep (GAS)

B-hemolytic strep (usually GAS)

Mild: PO PCN-V or Amox for 7-10 days

If PCN allergy use cephalexin, clinda, or erythro

Severe: IV PCN-G 2-8 MU daily

What are the organisms that cause impetigo? When do you consider topical vs oral therapy? What do you use for treatment?

• Strep pyogenes and Staph aureus 

• Topical for mild → Mupirocin or Retapumulin for 5 days

• Oral for more severe (multiple lesions/outbreak) → Dicloxacillin or Cephalexin for 7 days 

  • If culture is only S. pyogenes → PCN for 7 days 

  • If PCN allergy use cephalexin