Cellulitis

Risk: Age is not generally considered a risk factor for cellulites, although some studies show slightly higher incidence in individuals over age 45. Individuals who are immunodeficient as a result of genetic conditions (e.g., Job syndrome), illness (e.g., HIV infection, cancer), or immunosuppressive drugs (e.g., chemotherapy, corticosteroids, antirejection drugs in transplant recipients) are at increased risk of infections such as cellulitis. Diabetes impairs the immune system and decreases blood circulation, increasing risk of infection. Chronic skin conditions such as psoriasis, dermatitis, or eczema can create an opportunity for entry of infectious bacteria. Individuals who have recurrent fungal infections of the feet are greater risk for developing cellulitis. Impaired peripheral circulation such as arterial insufficiency or venous stasis is also a risk factor. Subcutaneous or intravenous drug injection, body piercing, and tattoos are all associated with higher risk for cellulitis. Cellulitis may also occur as a complication of certain surgical procedures (hip replacement, liposuction, breast surgery, vein surgery).

Incidence and Prevalence: Cellulitis can affect anyone of any age; cellulitis of the face is more common in children and adults over age 50 (Cunningham). The actual incidence of cellulitis is unknown because cases are seldom reported. Orbital cellulitis is uncommon but potentially very serious.

The incidence of infection by methicillin-resistant Staphylococcus aureus (MRSA) and other antibiotic-resistant bacteria has increased dramatically in recent years (Mayo Clinic Staff). Infection by these organisms is much more serious.

History: The individual may complain of a red, hot, swollen, and tender area of skin. Symptoms may also include fever or chills. The individual may report a recent history of trauma or a bite at the affected site. The individual who complains of redness and swelling of the eyelid may also report eye pain, impaired eye mobility, and visual changes.

Physical exam: The appearance of red, swollen, tender skin that is warm to the touch is usually sufficient for diagnosis. The texture of the skin may resemble orange peel (peau d'orange) and be firm to the touch. Regional lymph nodes may be inflamed and swollen. Adjacent skin may reveal red streaks characteristic of inflamed lymphatic vessels (lymphangitis). If the lower leg is affected, symptoms (warmth, pain, and swelling) may mimic those of clot formation in leg veins (venous thrombosis). Individuals with orbital cellulitis should undergo a thorough examination of the face, sinuses, teeth, mouth, and nasopharynx to identify the source of infection.

Tests: A complete blood count may be performed to determine the level of white blood cells, a sensitive marker of infection. Cultures of pus or other drainage from the area of infection and/or blood cultures may be performed to identify the causative organism(s). This is especially important if an unusual pathogen is suspected and can be helpful in guiding antibiotic therapy. Often, the causative agent is not identified, or the report shows multiple skin organisms that may include normal flora. Antibiotic sensitivity tests may be performed on the cultured organism(s) to aid in determining the most appropriate antibiotic therapy. Individuals with orbital cellulitis may require imaging studies (x-rays, CT, or MRI of the sinuses) to localize the source of infection.