The common bacterial skin infection can be dangerous–so find out if you're at high risk.

By Tolu Ajiboye
December 05, 2018

Cellulitis is an infection of the deep layers of the skin, the dermis and subcutaneous tissue. It’s caused by bacteria, and if it’s not treated immediately, cellulitis can become serious and even life-threatening if it spreads to the blood.

“Cellulitis is common, and the major cause is the streptococcus bacteria that reside on the skin,” says Amesh Adalja, MD, an emergency medicine doctor and senior scholar at the Johns Hopkins University Center for Health Security. Aside from the streptococcus bacteria, other kinds of bacteria that cause cellulitis are staphylococcus, methicillin-resistant staphylococcus aureus (MRSA), Haemophilus influenzae, and Clostridium perfringens.

The bacteria infect your skin in places where it’s broken or cracked. Breaks in your skin can be caused by scrapes, burns, surgery, fungal infections, and many other things. Even if the break in the skin is too tiny for you to see it, bacteria can get in.

Cellulitis can affect any part of the body, but it typically affects the legs, hands, and feet. It usually appears as red spots, pain, swelling, and warmth, and it may also cause a fever. “Cellulitis tends to occur more frequently in summer months,” Dr. Adalja says, possibly because the heat causes more sweating and swelling, leading to skin abnormalities. If you suspect that you have cellulitis, contact your physician as soon as possible.

Anyone can get the potentially dangerous skin infection if bacteria find their way into the layers of your skin. However, there are certain conditions that put you at a higher risk of developing cellulitis.

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A weak immune system

“The immune system is the means by which the body controls infection,” Dr. Adalja explains. “When the immune system is impaired, the ability to control infection is diminished and can allow microorganisms to proliferate and cause damage.”

People with compromised immune systems–due to things like cancer, HIV/AIDS, or certain medications–should take special precautions to keep skin clean in an effort to avoid getting cellulitis. “For example, keeping the spaces between the toes dry and free of infection is one general measure to take,” Dr. Adalja says. Other ways to practice good skin hygiene are washing scratches with warm water and soap, applying moisturizer to dry skin, and washing your hands often.

Diabetes

If you have diabetes, there are two ways you’re more at risk of getting cellulitis. The first is related to the complications of diabetes. Diabetic neuropathy (nerve damage) is a common complication of diabetes, and it sometimes makes you lose sensation, particularly in your feet. This means that if you get a foot injury, you may not notice–and that in turn makes you unable to treat it properly, leaving it open for bacteria to enter.

The second way having diabetes puts you at risk for cellulitis is that having high blood sugar–the hallmark of diabetes–negatively affects immune system function, allowing bacteria and other infectious microorganisms to thrive.

If you have diabetes, you can protect yourself against cellulitis at least in part by always wearing supportive shoes and wearing protective gloves when necessary. You should also be watchful so you can pick up on any signs of infection.

RELATED: 15 Ways High Blood Sugar Affects Your Body

Skin conditions

“Pre-existing skin conditions such as athlete’s foot allow skin bacteria to penetrate to deeper layers of the skin and cause infection,” Dr. Adalja explains. Athlete’s foot is characterized by blistering, cracked, or peeling skin under your foot, and that's what allows the bacteria to invade the skin and the layers beneath it.

Eczema also increases your chances of cellulitis. The skin condition means there’s damage to the barrier of your skin, and you may have more bacteria on your skin than normal, both of which could promote infection.

Chronic swelling

Lymphedema is a condition that causes chronic swelling. With it, the lymphatic system–crucial in helping your body fight disease–is not functioning well. Lymphatic fluid, which carries infection-fighting white blood cells, pools and builds up in the legs and arms. Having this condition puts you at a higher chance of getting cellulitis.

“[The] pooling of fluid in affected regions leads to swelling and can cause skin changes that predispose to infection,” Dr. Adalja says. The lymphatic fluid is also fertile ground for the bacteria to thrive once it enters the skin and soft tissue. Plus, the malfunction of the lymphatic system also means it’s less able to fight infection.

RELATED: 13 Reasons Your Feet Are Swollen

Wounds and Injuries

“Anything that causes a break in the skin such as a wound or abrasion can afford skin bacteria an opportunity to penetrate deeper,” Dr. Adalja explains. Make sure you’re washing and cleaning cuts or scrapes and keeping an eye on them for any signs of infection. Having bed sores can also leave you vulnerable to infection.

Vein problems

Normally, the veins in your legs keep blood moving toward your heart. But with venous insufficiency, the valves in these veins are damaged and don’t stop the blood from flowing backward into the legs. This causes blood to pool and accumulate in the legs, leading to pain, swelling, and, in some serious cases, open sores. Those sores make people with venous insufficiency more susceptible to getting cellulitis, as they are open points through which bacteria can easily invade the skin’s deep tissues.

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