Encyclopedia / C / Cellulitis



Cellulitis is a diffuse, spreading skin infection.


Cellulitis is a skin infection that sometimes accompanies damage to the skin, poor circulation, or diabetes. Streptococcal or staphylococcal bacteria enter the skin through a cut, puncture, ulcer, or sore, producing enzymes that break down the skin cells. Erysipelas is a superficial form of cellulitis.

Infants are particularly susceptible to buccal cellulitis, an infection of the skin on the cheek. The infection is characterized by skin discoloration and swelling and is more often misdiagnosed as a bruise. It is caused by any substance that may cause injury to the buccal mucosa, such as popsicles and ice cubes, and prolonged exposure of infants to low temperature. Other infections that are commonly mistaken as buccal cellulitis include erysipelas, severe impetigo, and insect bites.

Orbital cellulitis is a rare, acute infection of the eye socket. It affects primarily children, and the onset is rapid and severe. Bacteria enter the orbit of the eye, often from an infection in the sinuses, a boil on the eye or eyelid, or a foreign object. The soft tissue lining becomes infected. In most cases only one eye is affected. This is an acute and dangerous infection and may require hospitalization and antibiotic treatment.


The lower extremities are the most common site of infection. A skin abnormality (e.g., skin trauma, ulceration, tinea pedis, or dermatitis) often precedes the infection. Scars from saphenous vein removal for cardiac or vascular surgery are common sites for recurrent cellulitis, especially if tinea pedis is present. Frequently, however, no predisposing condition or site of entry is evident.

Streptococcus pyogenes is the most common cause of superficial cellulitis with diffuse spread of infection. Staphylococcus aureus occasionally produces a superficial cellulitis typically less extensive that of streptococcal origin and usually only in association with an open wound or cutaneous abscess. Cellulitis occurring after animal bites may be caused by other bacteria, especially Pasteurella multocida from dogs and cats.


In cellulitis, the skin becomes red and swollen and is both warm and painful to the touch and is sometimes accompanied by fever, malaise, chills, and headache. If antibiotics are not given, the condition may progress to abscesses (pockets of pus) and tissue damage.

Erysipelas is a superficial form of cellulitis characterized by redness, swelling, vesicles, fever, and pain. It is caused by a species of streptococci, which usually starts with a headache, fever, and general distress, followed by small, red patches that spread and swell so that the border may be easy to see and feel.


The diagnosis is usually made by medical history and physical examination alone.


In severe cases, antibiotics may be given intravenously for the first 24 to 72 hours, followed by oral antibiotics. Mild cases may only require oral antibiotics.

In severe cases that progress rapidly or are associated with necrosis (tissue destruction), necrotizing cellulitis-fasciitis is considered. This requires urgent surgical exploration.


Do the signs and symptoms indicate cellulitis?

Is there tissue damage?

What is causing the infection?

Will you prescribe antibiotics?

What are the side effects of the antibiotics?

When will the condition clear?

Keeping minor abrasions, cuts and bruises clean and free of continued trauma can lessen the likelihood of cellulitis.