Cellulitis is the medical term for inflammation and infection of the skin. It is often caused by the bacteria Streptococcus
(commonly known as strep and staph, respectively), which usually live on the skin of healthy people but when the skin is damaged (by a cut, scratch, or bug bite, for example), it can overgrow and cause cellulitis. Cellulitis causes the skin to look reddened, similar to a sunburn, and to be warm, tender, and swollen. The redness may spread quickly over the course of hours. The person may experience fevers or chills or feel ill. If left untreated, cellulitis can cause bacteria to enter the blood stream, which is potentially life threatening.
Who's At Risk
Cellulitis can occur in anyone of any age, sex, or race. It is more commonly seen in older adults, though children and teens are often affected. Any condition that predisposes someone to infections, such as diabetes, lymphedema, poor circulation, or a weakened immune system, and any condition that damages the skin, such as wounds, rashes, and bites, may lead to cellulitis.
Signs and Symptoms
The most common locations for cellulitis include the following:
- Lower legs
- Arms or hands
Cellulitis initially appears as pink to red, minimally inflamed skin. The involved area quickly progresses to deeper red, swollen, warm, tender skin that increases in size as the infection spreads. Occasionally, red streaks may radiate outward from the cellulitis. Blisters or pus-filled pockets (pustules) may be present.
Cellulitis may be associated with swollen lymph glands. Fever and chills are common.
There are no self-care options for cellulitis. While you are awaiting an appointment with your physician, you can elevate the involved body part in order to minimize swelling.
When to Seek Medical Care
If you develop a tender, red, warm, enlarging area on your skin, make an appointment with your physician as soon as possible. If you also have fever and chills or if the area involves the face, you should go to the emergency room.
If you are currently being treated for a skin infection that has not improved after 2–3 days of antibiotics, return to your doctor.
Community-associated methicillin-resistant Staphylococcus aureus
(CA-MRSA) is a strain of "staph" bacteria resistant to antibiotics in the penicillin family, which have been the cornerstone of antibiotic therapy for staph and skin infections for decades. CA-MRSA previously infected only small segments of the population, such as health care workers and persons using injection drugs. However, CA-MRSA is now a common cause of skin infections in the general population. While CA-MRSA bacteria are resistant to penicillin and penicillin-related antibiotics, most staph infections with CA-MRSA can be easily treated by health care practitioners using local skin care and commonly available non-penicillin-family antibiotics. Rarely, CA-MRSA can cause the serious skin and soft tissue (deeper) infection cellulitis, which requires intravenous (IV) antibiotics in most people to clear the infection. If you think you may have a cellulitis, contact your doctor immediately.
Treatments Your Physician May Prescribe
Although your physician may easily diagnose cellulitis, he or she may wish to order other tests such as blood work or skin biopsy. In addition, your doctor may wish to perform a bacterial culture in order to discover the particular organism that may be causing the cellulitis.
The procedure involves:
- Penetrating any blisters or pus-filled pockets with a needle, scalpel, or lancet.
- Rubbing a sterile cotton-tipped applicator across the skin to collect the sample.
- Sending the specimen away to a laboratory.
Typically, the laboratory will have preliminary results within 48–72 hours if there are many bacteria present. However, the culture may take a full week or more to produce final results. In addition to identifying the strain of bacteria that is causing the cellulitis, the laboratory usually performs antibiotic sensitivity testing in order to determine the medications that will be most effective in killing off the bacteria.
While waiting on the results from the bacterial culture, your doctor will probably want to start you on an antibiotic to fight the most common bacteria that cause cellulitis. Once the final culture results have returned, the physician may change the antibiotic you are taking, especially if you are not improving.
Mild cases of cellulitis in otherwise healthy persons can be managed on an outpatient basis with oral antibiotic pills. Common oral antibiotics that are used to treat cellulitis include:
However, ill-appearing people or those who have other underlying illnesses may be hospitalized for observation and for the administration of intravenous antibiotics. Common intravenous antibiotics that are used in a hospital setting to treat cellulitis include:
If your doctor prescribes antibiotics, be sure to take the full course of treatment. In addition to prescribing antibiotics, your doctor will likely want to make sure that your underlying medical problems, if any, are being adequately managed.
Bolognia, Jean L., ed. Dermatology
, pp.1123-1124. New York: Mosby, 2003.
Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine
ed, pp. 1845, 1848, 1883. New York: McGraw-Hill, 2003.