Cellulitis is a bacterial infection of the soft tissues
It usually occurs on the face and lower legs
Treatment may require hospitalisation
A healthy body with a strong immune system is the best defence against cellulitis
Bacterial skin infection
Cellulitis is an acute non-contagious inflammation of the connective tissue of the skin (just under the outer layer of skin), resulting from Staphylococcus, Streptococcus or other bacteria.
It usually occurs in the tissues beneath the skin. It may also occur in tissues beneath mucous membranes or around muscle bundles or surrounding organs.
Cellulitis occurs most commonly on the face, arms or legs and is characterised by red, hot swollen skin.
Cellulitis of the face usually involves the cheek or periorbital or orbital tissues (in or around the eye), although other regions such as the neck may be affected.
Ludwig’s angina is the name given to cellulitis of the tissues of the floor of the mouth in the area around the submaxillary salivary gland.
Orbital cellulitis is an acute inflammation of the eye socket.
Pelvic cellulitis involves the tissues surrounding the uterus and is called parametritis.
Erysipelas is a severe form of cellulitis.
Necrotising fasciitis is the most severe form of cellulitis. This is the condition commonly referred to in the media as the "flesh eating bacteria". With necrotising fasciitis, the infection spreads extremely rapidly (sometimes an entire limb can be affected within a few hours).
The skin normally has many different types of bacteria living on it, but intact skin is an effective barrier that keeps bacteria from entering the body. When there is a break in the skin, bacteria can enter the body and grow there, causing infection and tissue inflammation. The skin tissues in the infected area become red, hot and painful.
Who gets it and who is at risk?
Any break in the skin (especially those caused by insect bites, stings, animal or human bites) are risk factors for cellulitis.
A history of peripheral vascular disease, diabetes mellitus, ischemic ulcers or recent cardiovascular, lung, or dental surgery can lead to cellulitis. The use of immunosuppressive or corticosteroid medications also increases susceptibility.
Symptoms and signs
Skin redness or inflammation that increases as infection spreads
Tight, glossy, stretched appearance of the skin
Pain or tenderness of the area
Skin lesion or rash that has a sudden onset, usually with sharp borders and rapid spread within the first 24 hours
Chills, shaking, warm skin, sweating, fatigue, muscle aches and a general ill-feeling
Additional symptoms that may be associated with the disease include nausea and vomiting, joint stiffness caused by swelling of the tissue over the joint and hair loss at the site of the infection
The appearance of the skin and underlying tissues is characteristic in cellulitis, allowing diagnosis by inspection. Occasionally swollen glands (lymph nodes) can be detected near the cellulitis.
Tests that may be performed are:
A CBC (complete blood count) will show an elevated white blood cell count (WBC), indicating a bacterial infection.
A blood culture may be performed to determine whether generalised infection has entered the bloodstream.
To prevent cellulitis, avoid skin breaks by wearing appropriate protective equipment when participating in risky work or sports. Keep any skin breaks clean and watch for redness, pain or other signs of infection.
Treatment is focused on control of the infection and prevention of complications. Antibiotics are given to control infection and analgesics (painkillers) may be needed to control pain.
At home, elevating the affected area and applying warm, moist compresses to the site aid the body in fighting infection by increasing blood supply to the tissues as well as by helping the swelling to subside. Rest should also help.
Cellulitis may require hospitalisation if the infection is difficult to treat.
In severe cases (such as necrotising fasciitis), extensive surgery may be necessary to remove the dead tissue and thus remove the source of more bacteria.
With correct treatment, cure is possible with 7-10 days. Cellulitis may be more severe if chronic disease is present or if the person is susceptible to infection due to a suppressed immune system. In extreme cases, complications may also arise such as tissue death (gangrene), generalised infection (sepsis), meningitis (if cellulitis is on the face) and inflammation of the lymph vessels (lymphangitis).
When to call the doctor
Call your doctor if symptoms of cellulitis are present. Call your doctor if you are being treated for cellulitis and new symptoms develop such as persistent fever, drowsiness, lethargy, blistering over the cellulitis or extension of the red streaks.
Reviewed by Dr Andrew Whitelaw, MBBCh (Witwatersrand), MSc (UCT), FCPath (Micro) (SA) Senior registrar, Department of Microbiology, University of Cape Town and Groote Schuur Hospital