CanadiEM Frontline Primer

CanadiEM Frontline Primer – Skin and Soft Tissue Infections

In Medical Concepts by Geoffrey CompLeave a Comment


Skin and soft tissue infections are a common chief complaint and continue to be an increasingly common chief complaint in the emergency department.​1–4​ Abscess and cellulitis are the two most common conditions encountered, but it is important to have a high clinical index of suspicion for some of the true cutaneous emergencies.

Currently, there are no cases of COVID-19 with ONLY cutaneous symptoms. Make sure to complete a good review of systems for patients presenting with skin and soft tissue complaints to ensure they do not have concomitant complaints concerning for COVID-19 symptoms.

Can’t Miss Diagnoses

  • Necrotizing Fasciitis
  • Toxic Shock Syndrome
  • Venous Thromboembolism (e.g. DVT)
  • Peripheral Arterial Occlusion
  • Abscess requiring drainageTendon Rupture
  • Cellulitis
  • Burns (including chemical)
  • Lymphangitis

Points to focus upon


To note and document; Tetanus status, anticoagulation, surgical manipulation if any.
Ask about recent intercurrent febrile illnesses.
May have “pain out of proportion” or localized hypoesthesia.


Check for peripheral pulses (they are the vital signs of the extremities!) – if absent, consider peripheral vascular disease.
CAUTION – Absent pulses, paresthesias, pallor, pulselessness may be signs of vascular occlusion (arterial clot) or compartment syndrome (e.g. from crush injury, recent fracture reduction, etc.)

For infections:
Look for “portals of entry” for infection (abrasions, recent surgery).
Check joints for any involvement.
Examine for rapidly spreading rash, purulence, bullae, blisters, crepitus.

Caution! Necrotizing Fascitis patients break all the rules:
– They may look surprisingly well.
– They may NOT have any overlying cellulitis/rash
– They may have a flat affect (known as “La Belle Indifference”).

Point-of-Care Ultrasound (to be done only for those with formal training and/or certification for interpretation):
Can be useful to diagnose smaller abscesses if drainage point is not obvious.

CanadiEM Frontline Primer - Skin and Soft Tissue Infections
Approach to Purulent SSTI
CanadiEM Frontline Primer - Skin and Soft Tissue Infections
Approach to Non-Purulent SSTI


While many skin and soft tissue infections are diagnosed through history and physical exam, additional lab testing and imaging may be warranted in the following special circumstances:


For infections encompassing a large surface area, crossing a large joint, concern for deep extension into muscle/bone, or on hands/genitals, consider specialty consult if available. Proximity of the lesion to an indwelling medical device including prosthetic joint, vascular access port or vascular graft.


Conditions/medications that may affect wound healing: Diabetes, Peripheral vascular disease, Immunosuppressant medications, etc.

Systemic Involvement

Look for vital sign abnormalities indicating possible sepsis. Consider laboratory testing for concerning presentations.

Rapid Progression

Rapid progression of erythema or progression of cellulitis after 48 hours of oral antibiotic therapy

Lab work that may be helpful to get :

  • CBC, BUN, Cr, Lytes, Glucose, VBG,
  • Consider Blood Cultures PRIOR TO antibiotics
  • C-reactive protein (CRP)
  • Consider joint aspiration (if joint is involved, but there is no overlying cellulitis)

DO NOT DELAY SURGICAL INTERVENTION IF SUSPECTING NEC FASC. Definitive Management is surgical debridement.

Clinical Decision Tools


Check your specific hospital guidelines for specific local antibiotic resistance as well as dosing and duration.

Necrotizing Fasciitis

1. Surgical Debridement
2. While awaiting OR to be ready, consider empiric antibiotic therapy:
One of [ Meropenem 1 g IV q8h OR Piperacillin-tazobactam 3.375 g IV q6h ]
One of [Vancomycin 15 mg/kg q12 h IV OR Linezolid 600 mg IV q12h OR Clindamycin 600 mg IV)
AGAIN, DO NOT DELAY SURGICAL INTERVENTION IF SUSPECTING NEC FASC. Definitive Management is surgical debridement.

Purulent SSTI

Severe purulent SSTI:
i. IV Piperacillin/Tazobactam and Vancomycin; or
ii. Oral or IV Clindamycin (same bioavailablity); or
iii. IV Linezolid

Mild/Moderate purulent SSTI: chose one or combination:
i.Oral TMP/SMX; or
ii.Oral or IV Clindamycin; or
iii.Oral Doxycycline
Of note, if no overlying cellulitis or comorbid conditions, Choosing Wisely Canada recommends discussing the use of antibiotics with patients as the benefits conferred by antibiotics may not outweigh the risks associated with their use.

Non-Purulent SSTI

Severe SSTI:
I. IV Piperacillin/Tazobactam and vancomycin and IV Clindamycin ( if concern for necrotizing infection)

Mild/moderate SSTI:
I. Oral Cephalexin; or
ii. IV Cefazolin; or
iii. Oral or IV Clindamycin.


  • Consider oral antibiotics whenever possible. 5-7 days. Usually, first-generation cephalosporin (e.g. cephalexin) to start.
  • If progressing despite antibiotics or signs of systemic infection, consider IV cephalosporins.
  • If allergic (anaphylaxis) to cephalosporins, may consider Clindamycin as an alternative therapy (Bonus: it has same bioavailability both PO or IV, so go ahead and treat PO – just ask the patient to also start probiotics since they may get antibiotic-related diarrhea).

Recommended reading, videos, and podcasts

The following is part of the CanadiEM Frontline Primer. An introduction to the primer can be found here. To return to the Primer content overview click here.

This post was copyedited and uploaded by Evan Formosa.


  1. 1.
    Russell F, Rutz M, Rood LK, McGee J, Sarmiento E. Abscess Size and Depth on Ultrasound and Association with Treatment Failure without Drainage. WestJEM. February 2020:336-342. doi:10.5811/westjem.2019.12.41921
  2. 2.
    Pallin DJ, Egan DJ, Pelletier AJ, Espinola JA, Hooper DC, Camargo CA Jr. Increased US Emergency Department Visits for Skin and Soft Tissue Infections, and Changes in Antibiotic Choices, During the Emergence of Community-Associated Methicillin-Resistant Staphylococcus aureus. Annals of Emergency Medicine. March 2008:291-298. doi:10.1016/j.annemergmed.2007.12.004
  3. 3.
    Stevens DL, Bisno AL, Chambers HF, et al. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue          Infections: 2014 Update by the Infectious Diseases Society of America. Clinical Infectious Diseases. July 2014:e10-e52. doi:10.1093/cid/ciu296
  4. 4.
    Breyre A, Frazee BW. Skin and Soft Tissue Infections in the Emergency Department. Emergency Medicine Clinics of North America. November 2018:723-750. doi:10.1016/j.emc.2018.06.005

Geoffrey Comp

Emergency medicine physician in Phoenix, AZ. Creighton University School of Medicine/Maricopa Medical Center core residency faculty. Interest in medical education and developing various ways to teach emergency medicine. Clinical Assistant Professor - University of Arizona College of Medicine Phoenix.

Teresa Chan

Senior Editor at CanadiEM
Emergency Physician. Medical Educator. #FOAMed Supporter, Producer and Researcher. Chief Strategy Officer of CanadiEM. Associate Professor, Division of Emergency Medicine, Department of Medicine, McMaster University.