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Cellulitis: An Overview of Symptoms, Diagnosis and Treatment

October 28, 2014

By Laurie Swezey RN, BSN, CWOCN, CWS, FACCWS

This article is designed to provide a review of cellulitis, an infection affecting the skin which can be life-threatening if not treated.

What is cellulitis?

Cellulitis is the term used to describe inflammation of the skin and subcutaneous tissues, most often caused by acute infection. The two most common pathogens associated with cellulitis are Streptococcus pyogenes and Staphylococcus aureus.

Staphylococcus aureus VISA 2

Staphylococcus aureus under 20,000x magnification. [From Wikimedia Commons]

How does cellulitis occur?

Cellulitis is caused by a breach in the skin, i.e. a laceration, insect bite or sting, fissure or puncture wound. Sometimes the breach in the skin is so tiny that it cannot be seen with the naked eye. Organisms present on the skin (or skin appendages) gain access to the dermis and begin to multiply.

What are the common risk factors for cellulitis?

Obviously, individuals with altered immunity are at higher risk of developing cellulitis, including diabetic patients. Other risk factors include:

  • Lymphatic obstruction
  • Pressure ulcers
  • Obesity
  • Venous insufficiency
  • Tinea pedis (athlete’s foot), cracks or peeling of the skin between the toes
  • Injury or trauma resulting in a break in the skin
  • Bites from insects, animals or other humans
  • Chronic kidney or liver disease

What are the signs and symptoms associated with cellulitis?

As with most infections, the cardinal signs of infection will be present: redness (erythema), pain, edema (swelling) and warmth. The patient may also experience:

  • Swollen lymph glands close to the area of infection
  • Malaise, chills and fever
  • Lymphangitic spread (red streaks moving outward and away from the site of the infection)

Skin numbness, sloughing, high fever, hemorrhaging under the skin and/or rapid progression and worsening of signs and symptoms may signal a severe infection affecting the soft tissue as well as the skin and should prompt a surgical consult.

How is cellulitis diagnosed?

Generally, cellulitis is fairly simple to diagnose. The affected area (most often the lower leg) will be red, warm and tender to touch. Varying degrees of edema may also be present. When infection is severe, the patient may appear unwell.

Diagnostic testing may be limited to performing a complete blood count, which may reveal a left shift on the differential in more severe infections. Patients who appear to be systemically ill should also have blood cultures drawn, although only 5 to 15% of patients will have positive cultures. Wound culture or aspiration should be performed if there is drainage present. Ultrasound, MRI or CT scan may be performed when serious signs and symptoms are present to help identify any underlying pathology, such as an occult abscess.

How is cellulitis treated?

Mild, uncomplicated cellulitis (minimal swelling and pain with no symptoms of systemic infection) is generally treated with oral antibiotics. More severe infections may require treatment with intravenous antibiotics. If cellulitis follows an abscess, the abscess should be drained. Cellulitis of the face or periorbital cellulitis often necessitates a hospital stay and intravenous antibiotics, as the infection may spread to the eye(s).

Cellulitis may cause sepsis in susceptible individuals; these patients may require admission to the ICU, particularly if they are hemodynamically unstable. Patients who fail to respond to antibiotic therapy and/or patients with an unusual bacterial strain can benefit from an infectious disease consultation.

Herchline T. Cellulitis. Medscape. Updated August 19, 2014. Accessed October 13, 2014.
Beldon P. The Assessment, Diagnosis and Treatment of Cellulitis. Wound Essentials. 2011;6:60-68.

About The Author
Laurie Swezey RN, BSN, CWOCN, CWS, FACCWS, is a Certified Wound Therapist and enterostomal therapist, founder and president of, and advocate of incorporating digital and computer technology into the field of wound care.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, HMP Global, its affiliates, or subsidiary companies.