The elderly and young are at greatest risk of cellulitis from cuts and grazes.
The elderly and young are at greatest risk of cellulitis from cuts and grazes.
Nancy Oughton wasn’t particularly bothered when she fell and cut her arm while pottering around in her kitchen on Christmas Day. “I must have caught my arm on the corner of the stove when I fell and got a nasty gouge near my elbow.” She put a plaster on it and assumed everything would be fine. As it turned out, she needed two stitches, and the doctor she saw at the after-hours clinic shortly after Christmas also prescribed oral antibiotics to be on the safe side.
Two days later, however, her elbow was very painful and the skin around it was red, hot and swollen. Another trip to the after-hours clinic saw the 89-year-old with a cannula in her arm, through which she was given intravenous antibiotics for several days to treat cellulitis, a common bacterial skin infection.
Most cases of cellulitis start with a visible cut or injury. In some cases, says Mark Thomas, an Auckland infectious diseases specialist, the injury can be very small.
“Sometimes it can just be a little bit of cracked skin between the toes.”
Occasionally, for reasons that no one really understands, cellulitis can develop in the absence of any visible injury. The main symptoms are tenderness, swelling and redness; the skin can also feel hot and some people develop a fever or feel unwell.
Cellulitis is caused by two main groups of bacteria – streptococcus and staphylococcus – and in most cases it’s easily treated using oral antibiotics. It’s also important to get plenty of rest and to elevate the affected area to allow any fluid to drain out of it.
“The importance of rest and elevation can’t be emphasised enough,” says Thomas. “If you have cellulitis in your leg, the foot must be elevated above the buttocks when you’re lying down or sitting in a chair.”
Anyone can develop cellulitis, but as with most infectious diseases, children and older people are more susceptible to it.
That’s partly because older people have lower immunity levels, and young children haven’t yet encountered the full range of bacteria that
can cause infections. An additional risk factor for cellulitis is the fact that children are more likely to get the cuts and grazes that can lead to skin infections, and older people often have fragile skin that can tear easily. Socio-economic factors also play a part: Maori and Pasifika children are more likely to develop skin infections of all kinds, including cellulitis.
Although cellulitis is rarely life-threatening, it’s important to seek medical treatment to prevent it spreading to the lymph nodes and bloodstream. The Ministry of Health recommends going to a doctor if the infected area is larger than a 10c piece. Thomas says the symptoms can continue for up to 48 hours after starting antibiotics. “We expect the redness and swelling and warmth to persist for one to two days at least. It’s not a sign that the antibiotics aren’t working.”
Most people fully recover in five to seven days.
It’s also important to see a doctor to rule out the much rarer but life-threatening skin infection necrotising fasciitis (or flesh-eating disease), which has similar – though much more severe – symptoms and needs to be treated in hospital. Most people with necrotising fasciitis will have severe pain and be very unwell, and they require not just intravenous antibiotics but also surgery to remove the infected tissue.
“The doctor can assess whether the degree of illness is out of proportion to what they’ve seen in a person with cellulitis and whether the tenderness is much worse than they would expect,” Thomas says.
People who have had one episode of cellulitis have an elevated risk of another. To prevent recurrent episodes, it’s important to avoid getting further cuts and scrapes and to get on top of conditions that allow bacteria to enter the skin, such as athlete’s foot or eczema.
Long-term antibiotic treatment can also help. A recent British study found that taking a low dose of penicillin halved the rate of recurrent episodes of cellulitis.
“If someone has had repeated episodes, I would recommend taking 250mg of penicillin twice a day for months – or sometimes years.”
It’s important to rule out the rarer but life-threatening flesh-eating disease necrotising fasciitis.