Cellulitis is a non-contagious bacterial infection of the skin and underlying skin tissue. It is most commonly caused by Staphylococcus aureus (staph) and Streptococcus (strep), but many types of bacteria can cause the infection.
Cellulitis is characterized by redness, tenderness, warmth and swelling in the affected area. Sometimes the infection appears on areas where the skin has been broken, such as insect bites, skin ulcers, injuries and surgical wounds. Other times it appears without an apparent skin injury, though microscopic cracks are usually to blame. Fever, chills, blisters and swollen lymph nodes may develop.
Cellulitis can appear anywhere on the body, but the lower leg, feet, arms and neck are the most common. Sometimes the condition appears on the abdomen or chest, but that is usually following surgery or trauma wounds.
Though cellulitis can quickly spread to other parts of the body, it is not a contagious condition. This means you cannot spread it to other people.
Broken skin is generally the cause of cellulitis, as wounds leave the skin’s deeper layers (dermis and subcutaneous tissue) vulnerable to invasion from bacteria like Staphylococcus (staph) and Streptococcus. However, conditions such as chronic edema (swelling), Athlete’s foot, diabetes, eczema, psoriasis, chickenpox, shingles, intravenous drug use and conditions that compromise the immune system (HIV/AIDS, for example) can predispose to the development of the skin infection, as can obesity and pregnancy.
Cellulitis is a common infection that affects both men and women of all ages. However, middle-aged and elderly people seem to be affected the most.
A more serious staphylococcus infection called methicillin-resistant Staphylococcus aureus (MRSA) is ever increasing.
Cellulitis is commonly treated with antibiotics containing penicillin. Because the bacteria typically infects the deeper layers of skin, oral antibiotics may not be powerful enough to eradicate the condition. When this happens, intravenous antibiotics may need to be administered.
If cellulitis is not treated, the infection can spread to the deep layer of tissue called the fascial lining (an example of this is necrotizing fasciitis, or flesh-eating strep). It can also spread to the bloodstream, a serious and potentially life-threatening condition called sepsis.
Healthy people can usually prevent cellulitis from developing by practicing proper hygiene, avoiding skin wounds and promptly treating any injuries or cuts. Cellulitis is not preventable in people with predisposing conditions or weakened immune systems.