Cellulitis facts
- Cellulitis is a bacterial infection of the skin and tissues beneath the skin.
- Staphylococcus and Streptococcus are the types of bacteria that are usually responsible for cellulitis, although many types of bacteria can cause the condition.
- Sometimes cellulitis appears in areas where the skin has broken open, such as the skin near ulcers or surgical wounds.
- Symptoms and signs of cellulitis include
- redness,
- pain and tenderness,
- swelling, and
- warmth of the affected area.
- Cellulitis can occur anywhere in the body. Cellulitis frequently affects the legs.
- Cellulitis is not contagious.
- Complications of cellulitis include spread of the infection into the bloodstream or to other body tissues.
- Cellulitis is treated with oral or intravenous antibiotics.
What is cellulitis?
Cellulitis is a bacterial infection of the skin and tissues beneath the skin. Unlike impetigo, which is a very superficial skin infection, cellulitis is a bacterial skin infection that also involves the skin's deeper layers: the dermis and subcutaneous tissue.
The main bacteria responsible for cellulitis are Streptococcus and Staphylococcus ("staph"), the same bacteria that can cause impetigo and other diseases. MRSA (methicillin-resistant Staph aureus) can also cause cellulitis. Sometimes, other bacteria (for example, Hemophilus influenzae, Pneumococcus, and Clostridium species) may cause cellulitis as well.
Cellulitis is fairly common and affects people of all races and ages. Men and women appear to be equally affected. Although cellulitis can occur in people of any age, it is most common in middle-aged and elderly people. Cellulitis is not contagious.
What are cellulitis symptoms and signs?
Cellulitis has characteristic symptoms and signs. Symptoms usually begins as a small area of tenderness, swelling, and redness that spreads to adjacent skin. The involved skin may feel warm to the touch. As this red area begins to enlarge, the affected person may develop a fever, sometimes with chills and sweats, pain, and swollen lymph nodes ("swollen glands") near the area of infected skin.
Where does cellulitis occur?
Cellulitis may occur anywhere on the body; the legs are a common location. The lower leg is the most common site of the infection (particularly in the area of the tibia or shinbone and in the foot; see the illustration below), followed by the arm, and then the head and neck areas. In special circumstances, such as following surgery or trauma wounds, cellulitis can develop in the abdomen or chest areas. People with morbid obesity can also develop cellulitis in the abdominal skin. Special types of cellulitis are sometimes designated by the location of the infection. Examples include periorbital and orbital cellulitis (around the eye socket), buccal (cheek) cellulitis, facial cellulitis, and perianal cellulitis.
What does cellulitis look like?
The signs of cellulitis include redness, warmth, swelling, tenderness, and pain in the involved tissues. Any skin wound or ulcer that produces these symptoms or signs may be developing cellulitis.
Other forms of noninfectious inflammation may mimic cellulitis. People with poor circulation in the legs, for instance, often develop scaly redness on the shins and ankles; this is called "stasis dermatitis" and is often mistaken for the bacterial infection of cellulitis.
What are cellulitis risk factors?
Most commonly, cellulitis develops in the area of a break in the skin, such as a cut, small puncture wound, or insect bite. In some cases when cellulitis develops without an apparent skin injury, it may be due to microscopic cracks in the skin that are inflamed or irritated. It may also appear in the skin near ulcers or surgical wounds.
In other circumstances, cellulitis occurs where there has been no skin break at all, such as with chronic leg swelling (edema). A preexisting skin infection, such as athlete's foot (tinea pedis) or impetigo can be a risk factor for the development of cellulitis. Likewise, inflammatory medical conditions or diseases of the skin such as eczema, psoriasis, or skin damage caused by radiation therapy can lead to cellulitis.
People who have diabetes or diseases that compromise the function of the immune system (for example, HIV/AIDS or those receiving chemotherapy or drugs that suppress the immune system) are particularly prone to developing cellulitis.
Conditions or diseases that reduce the circulation of blood in the veins or that reduce circulation of the lymphatic fluid (such as venous insufficiency, obesity, pregnancy, or surgeries) also increase the risk of developing cellulitis.
