Cellulitis and erysipelas

Cellulitis is a relatively common infection of the dermis and subcutaneous tissues, often due to streptococci (Figure 12.2). Erysipelas is an infection of the dermis only with a welldefined, raised edge which usually affects the face or lower leg or areas where there is less subcutaneous tissue. It can be hard to distinguish between the two and in practice the terms may be used interchangeably (Kilburn et al., 2003). Important precipitants include tinea pedis, lymphoedema venous insufficiency and being overweight as they all lead to skin barrier breakdown and the consequent entry points for infection (DTB, 2003). Cellulitis presents with an acute onset of red, painful, hot, swollen, smooth, shiny and tender skin, sometimes with bullae. There may also be systemic upset with nausea, shivering, malaise, fevers and rigors. It usually affects one limb only, nearly always a leg. Some cases arise through a break in the skin, e.g. bites, burns and scalds and cuts, eczema or ulcers.

Figure 12.2 Cellulitis. (Source: Graham-Brown and Burns, 2006.)

It is important to distinguish between cellulitis of the leg and varicose eczema as the two are often confused due to the erythematous inflammation found in both conditions (Quartey-Papafio, 1999). However, there are other clinical features by which to differentiate the two conditions. Crusting or scaling is the most important sign in varicose eczema and not present in cellulitis where the skin is smooth and shiny. Small vesicles are common in varicose eczema. These break down with the release of serous fluid which dries to form crusts which coalesce. Such blister formation is rare in cellulitis. Itching is present in varicose eczema but not cellulitis and the patient may have a history of varicose veins or deep vein thrombosis.

Varicose eczema should always be considered in the differential diagnosis of cellulitis of the leg. In varicose eczema, intravenous antibiotics are unnecessary. Treatment will be needed with 1:10,000 potassium permanganate solution and topical steroid and emollients (Quartey- Papafio, 1999).

Management

1. There are no published UK guidelines or consensus for treating cellulitis.
2. Hospital admission is advisable for neonates, the immunocompromised or those unwell with co-existing disease, those with severe cellulitis or with periorbital cellulitis and those who lack support at home or are not improving on treatment (DTB, 2003).
3. Treatment with phenoxymethylpenicillin or benzylpenicillin can be started ‘blind’ for mild uncomplicated cellulitis, as unless there is a likely portal of entry or secondary blistering, it is usually difficult to identify a specific bacteriological cause (DTB, 2003).
4. Drawing around the extent of the infection with a permanent marker pen can help to track for future comparison.
5. Flucloxacillin may be given in addition and this is common practice in more severe cases. Whether these are given orally or intravenously will depend on the patient’s condition.
6. Co-existing disease such as leg ulcers, toeweb intertrigo, lymphoedema, venous insufficiency, leg oedema and obesity should also be addressed.
7. Recurrence is common (up to 30%) (DTB, 2003). There is a strong association with oedema and multiple episodes of cellulitis (Cox, 2006) where the vicious cycle of oedema predisposing to cellulitis and cellulitis being a cause of persistent oedema must be appreciated. Cox suggests that interventions such as the reduction of oedema or more prolonged antibiotic therapy may reduce the risk of recurrent infection.