What are Skin Infections?
Skin infections occur when the skin’s resistance to attack is lowered, or overwhelmed, by micro -organisms. In either case, the infecting organisms reach the layers of the skin under the surface where they can cause inflammation and damage.
What causes Skin Infections?
The epidermis (outer layer of the skin) is highly resistant to infection, but if this barrier is breached by cuts or abrasions, infection becomes more likely. The skin also has its own immune defenses, which include immunoglobulins (special proteins which destroy invading organisms). Strong sunlight can weaken these defenses, resulting, for example, in cold sores.
Some of the more common types of viral skin infections are:
- Chickenpox: This is acquired by inhaling infected droplets expelled during coughing or sneezing. The virus migrates to the skin where it causes crops of tiny irritating, crusting blisters.
- Shingles: This is caused by the chickenpox virus, which has lain dormant in the nerves for years, after an attack of chickenpox. Symptoms include tenderness and hypersensitivity of the skin, blisters, and sometimes, persistent pain.
- Cold sores: These may be transmitted by kissing the lips and face. They form small, tense, painful blisters that cause crusts and then heal in about a week.
- Genital herpes: This is caused by a sexually transmitted strain of the cold-sore virus.
- Warts and veruccas: Viruses cause all these from the human papilloma group.
The more common bacterial infections of the skin include:
- Boils: These result from infection of the skin pores with staphylococcal bacteria, causing small local abscesses with inflammation and pain.
- Impetigo: This causes areas of blistering, weeping and yellow crusts that may be wide spread. It is most common in children.
- Cellulitis: This occurs where streptococcal infection of the skin has lead to a rapidly spreading inflammation and accompanying fever. It can be dangerous if it progresses to septicaemia (blood poisoning).
The following represent the more common fungal skin infections.
- Tinea: This group includes tinea pedis (athlete’s foot), tinea corporis (body tinea), tinea cruis (crutch or jock itch), and tinea capitis (head tinea). Tinea can be caught by direct contact with an infected person or animal, or directly via infected objects such as towels and changing room floors.
- Thrush: Known as candidiasis, its cause is the fungus Candida albicans. Mucous membranes such as the mouth or vagina are usually affected, but it readily spreads to moist areas of the skin causing an itchy red rash with white patches on it.
- Pityriasis versiclor: This is a superficial fungal infection mainly affecting the trunk. Either increased or decreased pigmented patches appear on the skin and patients may notice that they do not tan properly in the affected area.
- Local redness
- Blisters that may crust or flake