Dr. Roach: How does one get cellulitis?
Dear Dr. Roach: What is cellulitis, and how does one get it?
I live in a retirement facility, and two ladies at my dining table have it. It seems to be very painful and difficult to heal.
Should I take any precautions to prevent getting it?
Dear R.G.: Cellulitis is an infection of the skin. It involves the full thickness of the skin, so it differs from the related infection called erysipelas, which is an infection of just the outer layer.
Most cases of cellulitis are caused by Streptococci, but Staphylococcus aureus (“staph infections”) are increasingly problematic, especially those caused by methicillin-resistant Staphylococcus aureus, also called MRSA.
The biggest risk factor for developing cellulitis is a lack of skin integrity. Trauma to the skin, such as a simple abrasion, a small cut or an insect bite, is a common way for the bacteria, which normally live on (“colonize”) the skin, to get through the skin barrier and cause an infection.
Skin conditions such as eczema, or an infection with, say, a fungus, are other ways the bacteria can get in. Chronic edema — from heart, liver or kidney disease, from lymphedema or from medications — can cause small cracks in the skin that can’t be seen easily, but that are large enough to allow bacteria to enter.
Cellulitis can occur anywhere on the body, but it is most commonly seen in the legs and feet.
Having a weakened immune system — from any cause, including disease or treatments that affect the immune system — predisposes one to developing cellulitis.
Longstanding diabetes, which affects the small blood vessels, is another risk factor for the disease. Just plain dry skin can cause subtle cracks. As the immune system tends to wane with age, advanced age itself can become a risk.
Person-to-person transmission of cellulitis is very rare, since it is predominantly something about the person, not simply exposure to the bacteria, which is most important in developing cellulitis.
Proper skin care is very key for those people that are at high risk, which includes anyone with a history of cellulitis, as well as anyone with the risk factors above.
This means applyng regular applications of moisturizers in people with dry skin, very careful nail care, using good footwear to protect the feet from trauma and prompt care of any skin condition.
Email questions to ToYourGoodHealth@med.cornell.edu.