Definition

Cellulitis is an inflammatory skin disease that affects the middle layer of the skin (the dermis) and is caused by a bacterial infection. Cellulitis can occur in any area of the body and usually begins with a wound in the skin where the bacterial infection enters. Cellulitis can cause the affected area of skin to become swollen and inflamed, as well as cause pain and warmth in the skin. The swelling and redness that occur can spread quickly. On lighter skin tones, cellulitis will typically appear red or pink. On darker skin tones, it may appear dark brown, gray, or purple.

Cellulitis most often affects the feet and lower legs but can also occur on the face, arms, and other skin areas. A bacterial infection from cellulitis can spread into the bloodstream and become dangerous and life-threatening if not treated appropriately. The incidence of cellulitis in the United States is 14 million cases each year. Cellulitis usually occurs in young or old adults. There is no significant difference between male and female genders in the incidence of cellulitis.

Causes

The cause of cellulitis is usually infection from group A beta hemolytic streptococcus bacteria, such as Streptococcus pyogenes bacteria. Staphylococcus aureus bacteria are also one of the causes of cellulitis. Cellulitis begins with damage to the skin due to several things, for example:

• Cuts
• Bug bites
• Surgical wounds
• Burns

A wound on the skin can be a way for bacteria to enter the dermis layer of the skin. The immune system will fight the bacteria and cause an inflammatory reaction in the affected skin area. In addition, streptococcal bacteria release a chemical toxin that allows the bacteria to enter deeper layers until it spreads to the bloodstream and is potentially life-threatening. Despite the fact that bacteria are the disease's cause, cellulitis typically does not spread from person to person.

Risk Factors

Recognizing some of the risk factors plays an important role in the prevention and treatment of cellulitis. Everyone is at risk of developing cellulitis. However, there are some factors that can increase your risk of developing cellulitis.

Some of these risk factors include:

• Wounds or injuries to the skin
• Animal bug bites
• Surgical wounds
• Burns
• Scratches or cuts
• Certain medical conditions can lower the body's immunity, such as:
• Diabetes
• Leukemia
• HIV/AIDS
• Taking regular medications with immune-lowering side effects
• Vascular disorders of the hands or feet, such as varicose veins
• Liver diseases such as hepatitis or cirrhosis
• Other skin diseases such as dermatitis, psoriasis, or skin infections such as varicella or chickenpox
• Obesity
• Previous history of cellulitis
• Swelling of the arms or legs due to impaired lymph node flow (lymphedema)

Symptoms

Symptoms appear as the body's chemical response to the invasion of foreign bacteria in the dermis. Symptoms that you may feel if you have cellulitis include:

• Skin redness and swelling
• The skin feels warm and painful when pressed

You are advised to go to the emergency department if you have any of the following symptoms:

• High fever with chills
• Nausea and vomiting
• The cellulitis-affected area has grown larger and become harder
• Pain that feels increasingly severe
• The affected area of skin becomes numb or clammy

Diagnosis

The diagnosis of cellulitis is a clinical diagnosis, meaning that a doctor can determine the diagnosis of cellulitis through a specialized medical interview and physical examination of you, which can generally be seen through the characteristic appearance of the affected skin area. However, there are some supporting tests that can help a doctor make a definitive diagnosis of cellulitis.

Some of these supporting tests include:

• Complete blood tests (such as leukocyte and type counts) if it is suspected that the infection has spread into the bloodstream
• X-ray examination if there is a suspected foreign body in the skin or bone beneath the cellulitis-affected skin area.
• Blood culture, if needed

You should tell your doctor if you have had cellulitis before. When a patient first visits the doctor, details like the time the symptoms started will also help in the diagnosis and choice of the best treatment.

Management

Cellulitis requires comprehensive treatment. You are advised to:

• Rest the affected area
• Elevate or lift the affected skin area to relieve swelling and pain
• Take over-the-counter pain relievers, such as paracetamol or ibuprofen, to relieve the pain and also reduce fever, if any

Your doctor will ask you to take antibiotics for at least 5 days if the infection is not serious. If your infection is serious, then you will need to be hospitalized and will receive medication by injection until the infection is under control in about 2–3 days. After treatment at the hospital or health facility, you will continue to take medication at home.

Complications

When someone has cellulitis, complications can arise if the cellulitis is not treated properly. Some of the complications that can arise include:

• Infection that spreads through the blood and causes organ failure (sepsis)
• Infection of the bone (osteomyelitis)
• Infection of the lymphatic blood vessels (lymphangitis)
• Inflammation of the inner lining of the heart (endocarditis)
• Infection of the lining of the brain and spine (meningitis)
• Tissue death in the area with cellulitis (gangrene) can also occur

In addition, complications such as necrotizing fasciitis can also arise, which is an emergency condition resulting from infection of the skin at its deepest layer. Repeated occurrences of cellulitis can impair lymphatic drainage, which can lead to chronic swelling of the cellulitized leg area.

Prevention

After recognizing some of the risk factors you have, the next step is to improve the risk factors that can be improved. Here are the steps you can take, namely:

• Keep the skin moisturized with lotion or moisturizing cream to prevent skin damage
• Wear shoes that fit your feet and provide enough room for your feet when wearing shoes
• Cut toenails sufficiently without injuring the surrounding skin area
• Use special protective equipment when exercising
• Clean with soap and running water gently with petroleum jelly if there is damage to the skin
• Cover the injured skin with a plaster and change it daily
• Watch for signs of infection, such as redness, pain, or swelling
• Don't forget to follow your doctor's instructions regarding your medication regimen

In addition to the above steps, if you have never seen a doctor, it is best to have a general check-up. If any conditions or diseases are found to increase your risk of developing cellulitis, then treatment can be started as early as possible before the condition worsens.

When to See a Doctor?

If you experience symptoms of cellulitis, such as redness or swelling, and notice additional symptoms like fever, weakness, lumps, or spreading redness, you should seek the advice of a dermatologist or venereologist. 

The doctor will conduct a medical interview, a physical examination, and specific supporting examinations to determine the exact diagnosis and appropriate management.

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