Overview

Cellulitis is a common bacterial skin infection that affects the deeper layers of the skin and the underlying soft tissues. It typically appears as a red, swollen, and painful area of skin that feels warm to the touch. While cellulitis can occur anywhere on the body, it most commonly affects the lower legs. Without prompt treatment, the infection can spread rapidly and lead to serious health complications. Early recognition and medical care are essential to effectively treat cellulitis and prevent its progression.

Causes

Cellulitis is primarily caused by bacteria entering the skin through a break or crack, even if the wound is very small or invisible. The most common bacterial causes include:

• Streptococcus pyogenes (Group A Streptococcus): A frequent cause of cellulitis, known for rapid spreading infections.
• Staphylococcus aureus: Including Methicillin-resistant Staphylococcus aureus (MRSA), which can cause more severe and difficult-to-treat infections.

Factors that increase the risk of developing cellulitis include:

• Skin injuries such as cuts, insect bites, burns, or surgical wounds.
• Skin conditions like eczema, athlete’s foot, or ulcers that break the skin barrier.
• Chronic swelling (lymphedema) that stretches and weakens the skin.
• Weakened immune system from conditions like diabetes, cancer treatments, or HIV.
• Previous history of cellulitis.

Symptoms

Symptoms of cellulitis typically develop quickly and can range from mild to severe. The most common signs and symptoms include:

• Redness: A noticeable red area on the skin that expands over time.
• Swelling: Affected area becomes swollen and puffy.
• Warmth: The skin feels hot compared to surrounding areas.
• Pain and tenderness: The infected skin is painful to the touch and may ache.
• Fever and chills: Systemic symptoms like fever indicate the infection may be spreading.
• Blisters or skin dimpling: In some cases, blisters may develop, or the skin may look tight and shiny.
• Swollen lymph nodes: Lymph nodes near the infected area may become enlarged and tender.

Diagnosis

Cellulitis is usually diagnosed based on a physical examination and clinical history. Common diagnostic steps include:

• Physical examination: The doctor inspects the affected area for characteristic redness, swelling, and warmth.
• Medical history: Review of recent injuries, underlying health conditions, or previous cellulitis episodes.
• Blood tests: May show elevated white blood cell count or markers of inflammation, especially in severe cases.
• Wound culture: If there is an open wound or pus, a sample may be taken to identify the specific bacteria involved.
• Imaging tests: Ultrasound or MRI may be used in complicated cases to rule out abscesses or deeper infections.

Treatment

Treatment for cellulitis typically involves antibiotics and supportive care to resolve the infection and relieve symptoms:

• Antibiotics:
  • Oral antibiotics (e.g., penicillin, cephalexin, or clindamycin) are used for mild to moderate cases.
  • Intravenous (IV) antibiotics are necessary for severe infections, rapidly spreading cellulitis, or those with systemic symptoms like high fever.
• Pain relief: Over-the-counter medications such as acetaminophen or ibuprofen help reduce pain and fever.
• Rest and elevation: Elevating the affected limb helps reduce swelling and speed up recovery.
• Wound care: Proper hygiene and care of skin injuries can promote healing and prevent worsening of infection.
• Hospitalization: Required in severe cases, particularly when cellulitis is associated with high fever, sepsis, or risk of complications.

Prognosis

With timely and appropriate treatment, most cases of cellulitis resolve within 7 to 10 days. Pain, redness, and swelling usually improve significantly within a few days of starting antibiotics. However, some residual discoloration or swelling may take longer to resolve fully.

If left untreated, cellulitis can lead to serious complications, including abscess formation, sepsis, lymphangitis, or chronic skin changes. Recurrent cellulitis is possible, especially in individuals with underlying risk factors like lymphedema or diabetes. Preventive strategies, such as good skin care, prompt treatment of minor wounds, and managing chronic conditions, can help reduce recurrence risk and promote long-term skin health.