Some types of bacteria are naturally present on the skin and do not normally cause any harm. However, if the bacteria go deep into the skin, they can cause an infection. Bacteria can enter through cuts, grazes, or bites.
Here are some key points about cellulitis. More detail and supporting information is in the main article.
- Cellulitis occurs when bacteria enter the deep layers of skin through a wound or sore.
- The legs are most commonly affected.
- Risk factors include a reduced immune response and obesity.
- Diagnosis of cellulitis is relatively easy from observing external symptoms.
- Cellulitis nearly always responds rapidly to antibiotics.
Symptoms of cellulitis
Although symptoms may appear in any part of the body, the legs are most commonly affected. The affected area will become:
Some people may develop blisters, skin dimpling, or spots. They might also experience a fever, chills, nausea, and shivering.
Lymph glands may swell and become tender. If the cellulitis has affected the person's leg, the lymph glands in their groin may also be swollen or tender.
Causes of cellulitis
Cellulitis is an infection of the deeper layers of the skin.
Bacteria from the Streptococci and staphylococci groups are commonly found on the surface of the skin and cause no harm, however, if they enter the skin, they can cause infection.
For the bacteria to access the deeper skin layers, they need a route in, which is usually through a break in the skin. A break in the skin can be caused by:
- some skin conditions, such as eczema, athlete's foot, or psoriasis
Some people develop cellulitis without being able to identify a break in the skin.
Risk factors for cellulitis
The following risk factors increase the likelihood of cellulitis.
- Leg swelling (edema): This raises the chances of developing cellulitis.
- Weakened immune system: Including people who are undergoing chemotherapy or radiotherapy, those with HIV or AIDS, and older adults.
- Diabetes: If the diabetes is not properly treated or controlled, a person's immune system can be weaker, or they may have circulatory problems, which can lead to skin ulcers.
- Blood circulation problems: People with circulation issues may develop skin infections.
- Other skin infections: Conditions, such as chicken pox and shingles may cause skin blisters. If the blisters break, they can become ideal routes for bacteria to get into the skin.
- Lymphedema: This condition causes swollen skin that is more likely to crack. Cracks in the skin may become perfect entry routes for bacteria.
- Previous cellulitis: A person who has had cellulitis before has a higher risk than others of developing it again.
- Intravenous drug users: Drug addicts who do not have access to a regular supply of clean needles are more likely suffer from infections deep inside the skin.
Treatments for cellulitis
The following treatments are commonly recommended for cellulitis:
Antibiotics are commonly used to treat cellulitis.
Cellulitis nearly always responds rapidly to antibiotics. Some people experience a slight worsening of the reddening of the skin at the start of antibiotic treatment, which usually subsides within a couple of days.
However, anyone who experiences fever, vomiting, or any worsening of their symptoms after starting antibiotic treatment, should contact a doctor immediately. Many different types of antibiotics can be used to treat cellulitis. Which type the doctor prescribes will depend on what type of bacteria the doctor suspects has caused the infection.
Antibiotics are normally taken for 5-10 days, but treatment might last 14 days or more in some cases.
There is no way to treat cellulitis at home, and this condition needs to be treated by a doctor. If someone suspects they have cellulitis, they should call a doctor right away, and:
- drink plenty of water
- keep the affected area elevated, which helps reduce swelling and pain
- take painkillers, as recommended by a doctor
Treatment in the hospital
Some people with severe cellulitis may require hospital treatment, especially if the cellulitis is deteriorating, if the person has a high fever, is vomiting, fails to respond to treatment, or has recurrences of cellulitis. Most people who are treated in hospital will receive their antibiotic through a vein in their arm (intravenously, using a drip).
Diagnosis and complications of cellulitis
Diagnosis is usually fairly straightforward and does not generally require any complicated tests. A doctor will examine the individual and assess their symptoms. Although most cases of cellulitis are caused by streptococci and staphylococci, other medical problems like Lyme disease may look like cellulitis, so it is important to have good follow-up with a doctor after diagnosis.
The doctor may take a swab (sample) if there is an open wound. This can help them identify what type of bacteria is causing cellulitis. However, these samples are easily contaminated due to the multiple types of bacteria that live on the skin all the time. After treatment, the patient will need to return for a follow-up so that the doctor can confirm that the treatment has worked.
A small percentage of patients may have serious complications that include:
- Blood infection and sepsis: If the bacteria reach the bloodstream, the person has a higher risk of developing sepsis. A person with sepsis may have a fever, accelerated heartbeat, rapid breathing, low blood pressure (hypotension), dizziness when standing up, reduced urine flow, and sweaty, pale, cold skin.
- Infection moving to other regions: This is very unusual, but the bacteria that caused the cellulitis can spread to other parts of the body, including muscle, bone, or the heart valves. If this happens, the person needs treatment immediately.
- Permanent swelling: People who do not receive treatment for their cellulitis are at higher risk of having a permanent swelling in the affected area.
In the vast majority of cases, cellulitis treatment is effective, and the person will not experience any complications.
Although some cases of cellulitis are not preventable, there are things that people can do to reduce their chances of developing it:
- Treat cuts and grazes: If the skin is broken because of a cut, bite, or graze, it should be kept clean to reduce risk of infection.
- Reduce the likelihood of scratching and infecting the skin: The risk of the skin being damaged by scratching will be greatly reduced if fingernails are kept short and clean.
- Take good care of the skin: If the skin is dry, use moisturizers to prevent skin from cracking. Individuals with greasy skin will not need to do this. Moisturizers will not help if the skin is already infected.
- Protect the skin: Wear gloves and long sleeves when gardening; do not wear shorts if there is a likelihood of grazing the skin of the legs.
- Lose weight if you are obese: Obesity may raise the risk of developing cellulitis.