What is Cellulitis?
Cellulitis is a widespread skin infection caused by bacteria, with over 14 million cases reported each year in the USA alone. This disease causes expenses of around 3.7 billion dollars for outpatient care and results in 650,000 hospital stays each year. Cellulitis usually appears as a warm, red area on the skin that feels soft and tender to touch. It is a quick onset infection triggering inflammation under the skin and deep into the skin layers. Unlike some other types of infections, cellulitis doesn’t involve an abscess or pus. This condition is usually caused by strep bacteria, typically group A strep. However, some other bacteria like methicillin-sensitive Staphylococcus aureus also cause this disease. People with weakened immune systems, those carrying methicillin-resistant Staph bacteria, those who have been bitten by animals, or who have other health conditions like diabetes are at a heightened risk for cellulitis. Doctors who accurately identify cellulitis early on and start antibiotics promptly can often stop this infection.
What Causes Cellulitis?
Your skin acts like a shield, protecting the underlying layers of skin and the lymphatic system (body’s immune function) from natural skin bacteria and other harmful microbes. However, when your skin gets cut or broken, it opens a pathway for these bacteria to infiltrate the deeper layers of the skin. As these bacteria penetrate, they can spark an infection known as cellulitis that primarily impacts the deep skin layer and tissue beneath the skin.
The most common culprit causing cellulitis is a bacteria called group A beta-hemolytic streptococcus, more popularly known as Streptococcus pyogenes.
Anything that damages the skin’s protective barrier can increase the risk of cellulitis. Examples include skin wounds, surgical cuts, needle pricks from IV sites, cracks between the toes, insect or animal bites, along with other infections attacking the skin.
People with diseases like diabetes, conditions resulting in poor blood circulation such as venous insufficiency and peripheral arterial disease, and lymphedema (swelling related to the lymphatic system), are at a greater risk of developing cellulitis.
Risk Factors and Frequency for Cellulitis
Cellulitis is a condition that typically affects middle-aged and older adults. It doesn’t favor one gender over the other – men and women get it equally. In simple terms, for every 1000 people, about 50 are likely to experience cellulitis in a given year.
- Cellulitis is most common in middle-aged and older adults.
- Both men and women are equally affected by this condition.
- Approximately 50 out of every 1000 people will deal with cellulitis in a year.
Signs and Symptoms of Cellulitis
Cellulitis is a skin infection that causes redness, warmth, swelling, and tenderness. Patients may also feel unwell and run a fever. Healthcare providers will ask about the onset of symptoms and any contributing factors, such as recent travel or injuries. They will also inquire about the patient’s medical history to assess their risk factors. Providers carefully examine the affected skin area, marking the outline of redness if necessary. They assess the area for warmth, tenderness, and fluid discharge. Cellulitis is most commonly seen on the lower leg and is rarely present on both sides simultaneously. Providers also examine the spaces between the toes and check for normal feeling and pulses in the limbs. They look for blisters, fluid-filled sacs, orange-peel skin, and swollen lymph nodes.
Testing for Cellulitis
Cellulitis is diagnosed based on symptoms and physical examinations. Typical signs include redness, swelling, warmth, and tenderness. At least two of these symptoms must be present to confirm the diagnosis. Cellulitis usually affects the lower legs and is often found on one side. Doctors will check the patient’s skin for possible causes, such as small injuries, bug bites, or injection sites. They may also look for cracks or signs of athlete’s foot between the toes. Cellulitis can cause fluid buildup, leading to blisters and swelling. Imaging tests are usually not needed unless the infection is severe. Blood tests may be required in certain cases.
Treatment Options for Cellulitis
Patients with mild cellulitis should be given antibiotics to fight against streptococcal species and MSSA bacteria. Treatment should last at least 5 days. For non-pus forming cellulitis, cephalexin or clindamycin can be used. For pus-producing cellulitis, treatment against MRSA is necessary. Hospitalization and more powerful antibiotics are needed for severe cases. Intravenous antibiotics are started to fight group A strep bacteria. Broad-spectrum antibiotics may be prescribed for those with weakened immune systems. Uncommon organisms can cause cellulitis in certain situations. Underlying conditions should be addressed to reduce swelling. Systemic signs of infection should be monitored.
What else can Cellulitis be?
Cellulitis is a deep skin infection that commonly affects the lower legs. Erysipelas is a more shallow infection that affects the top layers of skin and has clear boundaries. Chronic venous stasis dermatitis is an inflammatory skin problem caused by poor blood flow in the legs. Necrotizing fasciitis is a rare infection that damages tissue beneath the skin and requires immediate surgery. Septic arthritis is a joint infection that typically affects the knee. Deep vein thrombosis is a blood clot in a deep vein, usually in the leg.
What to expect with Cellulitis
If a doctor quickly recognizes and starts treatment for cellulitis using the right antibiotics, patients generally start feeling better within 48 hours. Despite this, a reoccurrence of cellulitis within a year happens with 8 to 20% of patients, and the overall recurrence rate can even climb as high as 49%.
Recurrence can be prevented effectively if wounds or scrapes are promptly treated, if good hand hygiene is maintained, and by effectively managing any pre-existing health conditions. However, it’s also important to note that the initial antibiotic treatment fails about 18% of the time. Despite these setbacks, cellulitis is a condition with a good prognosis overall.
Possible Complications When Diagnosed with Cellulitis
If cellulitis, which is a skin infection, is not diagnosed and treated quickly, it can lead to multiple health problems. The bacteria causing cellulitis can get into the bloodstream. This condition is called bacteremia and can be identified by taking blood samples from patients showing symptoms like fever, fatigue, chills, etc. Doctors then use these results to decide the best antibiotics to treat the infection.
If bacteremia is not promptly and correctly treated, it may result in endocarditis. This is an infection in the inner lining of the heart.
Patients with cellulitis who show two or more signs of SIRS (Systemic Inflammatory Response Syndrome) – symptoms like a fever above 100.4 degrees F, rapid breathing, fast heart rate, or abnormal white blood cell count – are diagnosed with sepsis, a body-wide infection.
If cellulitis spreads from the skin and fatty tissues to the bones, it can lead to a severe bone infection called osteomyelitis.
In cases where cellulitis results in bacteremia, endocarditis, or osteomyelitis, patients will need a longer period of antibiotics, and sometimes even surgery.
Possible Complications of Cellulitis:
- Bacteremia (bacterial infection in the blood)
- Endocarditis (infection in the inner lining of the heart)
- Sepsis (body-wide infection)
- Osteomyelitis (bone infection)
- Possibility of surgery
- Long duration of antibiotics
Preventing Cellulitis
Patients are advised to closely follow doctor’s instructions when taking prescribed antibiotics. Keeping the affected area clean and dry is also very important. Elevating the infected part of the body above heart level, when possible, can help to reduce swelling.
The skin infection, known as cellulitis, should start getting better within a day or two after beginning antibiotic treatment. Healthcare providers may mark the affected area and patients should get in touch with them if they notice that the infection is spreading or not getting better with antibiotics, have frequent fevers, develop large blisters, or if the pain is getting worse.
Additionally, maintaining good hand hygiene and properly cleaning any skin wounds in the future is crucial to avoid such infections.
