What is Cellulitis

Cellulitis is a skin infection that is spreading. The symptoms of cellulitis are skin that is tender, involves swelling and redness of the skin. The individual may have a fever, and experience chills and sweats. They may have swollen lymph nodes near where the infection site is. Cellulitis is an infection that involves the deeper layers of the skin (dermis & subcutaneous). The bacteria involved in cellulitis infections are usually staphylococcus (Staph).

Individuals can have cellulitis where they have experienced trauma to the skin, where they have ulcers or where there are surgical wounds. Occasionally cellulitis will appear where there has been no apparent break in the skin.

Individuals who are at a higher risk of contracting cellulitis are those with diabetes and those who have impaired immune systems (HIV/AIDS or those on drugs to suppress their immune systems).

Cellulitis looks like inflamed skin (red, warm to the touch) that is also swollen.

Causes of Cellulitis

Although Staph is the most common cause of cellulitis, strep (group A) can also cause cellulitis. One form of a strep caused cellulitis is: erysipelas. There are other types of bacteria that can cause cellulitis especially in children under age 6, susceptible to Hemophilus influenzae. They often get this type of cellulitis on the face, arms and upper chest region.

Individuals who receive dog or cat bites can also get cellulitis caused by the Pasturella multocida bacteria.

Injury inflicted by a saltwater shellfish such as fish spine or crab pinch is due to the bacteria known as Erysipelothrix rhusiopathiae.

Those who live and work on farms, especially around pigs or poultry are also prone to injuries that can be infected by the Erysipelothrix rhusiopathiae bacteria that can turn into cellulitis.


There can be both bacterial and fungal causes of cellulitis. The most common organisms at fault for this skin infection are group A streptococci and Staphylococcus aureus.

Infants with cellulitis may receive the diagnosis of sepsis, which is caused by group B streptococci.

Fungal cellulitis is rare but can be caused by gram-negative rods or fungi in immunocompromised individuals.

Aeromonas hydrophila is a gram-negative rod and can cause cellulitis in wounds of individuals who have been in fresh water.

Tissue necrosis can result fro a particularly malignant form of cellulitis that is caused by pneumococcus.

At high risk are patients with diabetes, varicella, those who are post-op for mastectomy or those who have had vein stripping, those suffering from systemic illnesses or are immunodeficient. Those individuals who use chronic steroids are at an increased risk for cellulitis.

Cellulitis comes in two various forms (mild, and complicated). A doctor in outpatient clinic or office can treat mild cellulitis. The treatment is usually oral antibiotics. Doctors usually ask the patient to come back in 24 to 48 hours for evaluation. Complicated cellulitis is when there is extensive involvement at the site of infection, or the patient suffers from a systemic illness and also when there are signs of toxicity.

It is possible for cellulitis to develop into a life-threatening emergency so patients are instructed on what are normal conditions and what conditions need immediate medical attention. Serious conditions may require surgical debridement. Broad-spectrum antibiotic coverage is usually recommended in addition to fluid and vasopressor support and nursing staff monitoring.

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