If the infection is left untreated for too long, cellulitis can result in pockets of pus (abscesses) or the spread of bacteria into the bloodstream (bacteremia). However, most cases of cellulitis resolve with appropriate antibiotic therapy.
- Skin wounds
- Chronic lower leg swelling (edema)
- Athlete's foot (tinea pedis)
- Bites from insects, animals, or other humans
- Poor circulation in the legs (peripheral vascular disease)
- Weakened immune system due to underlying illness or medication
- Intravenous drug abuse
- Lower legs
- Arms or hands
Cellulitis may be accompanied by swollen lymph nodes, fever, chills, and fatigue.
If you are currently being treated for a skin infection that has not improved after 2–3 days of antibiotics, return to your doctor. You may need treatment with different medications, or the infection may have spread deeper into your skin.
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a strain of "staph" bacteria that is resistant to antibiotics in the penicillin family. This class of antibiotics has 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 CA-MRSA infections can easily be treated with commonly available nonpenicillin antibiotics. Rarely, CA-MRSA can cause a deeper skin infection, which usually requires intravenous (IV) antibiotics to treat the infection. There is an additional strain of MRSA (hospital-acquired MRSA), usually found in health care settings, that is susceptible only to intravenous antibiotics, so admission to the hospital is often needed for effective treatment.
A bacterial culture involves the following:
- Opening a blister or pus-filled bump with a needle, scalpel, or lancet after cleansing the skin.
- Rubbing a sterile cotton-tipped applicator across the skin to collect the sample.
- Sending the specimen to a laboratory.
While waiting for the results from the bacterial culture, your doctor may want to start you on an antibiotic to fight the most common bacteria that cause cellulitis. Once the final culture results have returned, your physician may change the antibiotic you are taking, especially if the infection is not improving.
Mild cases of cellulitis in a healthy person can be treated with oral antibiotic pills. Common antibiotics that are used to treat cellulitis include the following:
Arturo S, Weinberg AN, Swartz MN, Johnson RA. Soft-tissue infections: Erysipelas, Cellulitis, Gangrenous Cellulitis, and Myonecrosis. Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, eds. Fitzpatrick's Dermatology in General Medicine. 7th ed. New York, NY: McGraw-Hill; 2008:1720-1731.
Bolognia, Jean L., ed. Dermatology, pp.1123-1124. New York: Mosby, 2003.
Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed, pp. 1845, 1848, 1883. New York: McGraw-Hill, 2003.