The Facts About Cellulitis

A Painful Bacterial Infection That Can Spread If Untreated

Cellulitis of leg
Cellulitis of the leg. DEA Picture Library

Cellulitis is a bacterial infection of the deeper layers of the skin, specifically the dermis and subcutaneous tissue. In adults and children, cellulitis is most often caused by Streptococcus and Staphylococcus aureus bacteria. Another type, called Haemophilus influenzae type B, can cause cellulitis in children younger than 3, but this has become less common since vaccinations against this bacteria became routine.

Knowing the type of bacteria present in a cellulitic infection can help doctors select the best antibiotic to treat the condition.

Causes of Cellulitis

Bacteria are able to cause infection if they can get into the skin through a break in the tissue. With cellulitis, this can happen when there are cuts, scrapes, ulcers, spider bites, tattoos, or surgical wounds.

Cellulitis can also develop in skin that appears perfectly normal. Repeated infections often develop in areas where there has been damage to blood or lymph vessels. This can be caused by any number of things, including:

  • prior cellulitis infection
  • surgical removal of lymph nodes
  • removal of veins for vein grafts elsewhere in the body
  • prior or current radiation therapy to the area in question

What Cellulitis Looks Like

Before visible skin changes occur, persons with cellulitis will typically have fever, chills, and fatigue. The skin infection itself will usually be red, swollen, painful, and warm to the touch.

The texture of the skin will often be described as being "cobblestone" in appearance. Red streaks radiating from the area and swollen lymph nodes are also common features.

In children, cellulitis typically appears on the head and neck, while adults will most often get cellulitis on the arms or legs.

How Cellulitis Is Diagnosed

Cellulitis is usually diagnosed based on its appearance. Sometimes doctors will check a person’s blood count to see if the white blood cells are elevated (meaning that the immune system is fighting an infection). This is not always the case, particularly in the early stages, although changes will typically be seen as the infection progresses.

In people who are very ill, blood cultures may be performed to see if the bacteria has spread (disseminated) into the blood stream. Unfortunately, cultures are only positive in about five percent of cases, making a definitive diagnosis difficult.

Alternately, a doctor may opt to perform an aspiration, which involves the injection of sterile fluid into the infected tissue, after which fluids are drawn out in hopes of capturing some of the bacteria. This is usually done only in extreme cases since aspirations are return inconclusive results.

Treatment of Cellulitis

Cellulitis is treated with antibiotics. Most cellulitis infections require a 10-day course of an oral antibiotic. If the infection is on an arm – or especially the leg – elevating the extremity can speed healing. Intravenous antibiotics may be used in more severe cases, such as:

  • cellulitis of the face
  • persons who are seriously ill
  • people who are immune compromised, including those with HIV
  • infections that don't improve or get worse with oral antibiotics

Preventing Cellulitis

The best prevention of cellulitis is to take care of any break in the skin, which includes:

  • washing the wound daily with soap and water
  • applying a topical antibiotic to the wound
  • keeping the wound covered with a bandage
  • changing the bandage daily (or more often if it gets dirty or wet)

A Word From Verywell

Never hesitate to see a doctor if a wound you’re nursing suddenly get redder, becomes painful, or starts draining.

This is especially true if you have diabetes, are experiencing poor circulation, or are taking immune-suppressing drugs.

Waiting is rarely a good idea. A persistent rash or skin that is deeply red and inflamed may signal a more serious infection of the dermis (the inner layer of skin). As with all skin disorders, earlier detection allows for more effective treatment.

Sources:

Habif, T. "Bacterial Infections." Clinical Dermatology, 4th Edition. New York: Mosby, 2004: 236-62.

Halpern, A. and Heymann. W. "Bacterial Diseases." Dermatology. 2nd Edition. New York: Mosby, 2008: 1075-84.

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