Skin conditions due to fungi, bacteria and viruses – 10 cases

There is a sharply demarcated erythematous eruption on the leg. The skin is swollen and has a patchy peau d'orange appearance with vesicles and bullae containing serous and haemorrhagic fluid.

Erysipelas

Erysipelas is a superficial bacterial skin infection that rapidly extends into cutaneous lymphatic vessels. It is due to beta haemolytic streptococci, usually but not always due to group A toxins.

Erysipelas usually affects the face or the lower legs, initiated by some minor trauma. Venous disease, lymphoedema, dermatitis, tinea infection, insect bites and surgical or traumatic wounds may inoculate the bacteria into the skin. It is more common in those with immune compromise due to diabetes, alcohol abuse, infancy or old age.
The infection arises abruptly, resulting in fever, chills, and local swelling and tenderness of the affected site. A small red spot enlarges into a well-demarcated, warm, fiery-red, indurated and shiny plaque. The skin surface may blister. Petechiae, haemorrhagic blisters and necrosis may arise. Erythematous streaks leading to swollen and tender local lymph nodes are characteristic.
In contrast, cellulitis has no lymphatic component and affected areas have less well-demarcated margins.
On recovery, the surface skin desquamates. Recurrent infection leads to lymphatic obstruction, causing warty indurated skin (elephantiasis nostras verrucosa).

In typical cases no specific investigations are required, as they do not change management. Sometimes it is possible to culture the organism from blister fluid, and the diagnosis may be suspected by rising anti-streptococcal titres.

This should include:

• Elevation and rest of the affected limb
• Wet dressings applied to ulcerated and necrotic areas, followed by emollients during the later desquamating phase
• Antibiotics (oral or intravenous, depending on severity of presentation)

Penicillin, or in case of penicillin allergy, cephalosporin, is suitable for typical cases of erysipelas. There are regional protocols for the management of cellulitis that should be followed when in doubt as to the precise diagnosis.
Predisposing factors should be recognised and managed aggressively to reduce recurrences, for example, eradicate tinea pedis and encourage the use of compression stockings. Occasionally, the number of recurrences justifies long term prophylactic penicillin.