Bacterial skin infections

Author: Dr Amanda Oakley, Dermatologist, Waikato Hospital, Hamilton, New Zealand, 2002.

Some bacteria live on normal skin and cause no harm, such as some Staphylococcus species, Corynebacterium spp., Brevibacterium spp and Acinetobacter . Propionibacteria live in the hair follicles of adult skin and contribute to acne.

Some bacteria invade normal skin, broken skin from eczema/dermatitis or wounds (causing wound infection). Bacteria, like viruses, may also sometimes result in exanthems (rashes). The most common bacteria to cause skin infections are:

Less commonly, other bacteria may also cause infection with skin signs. These include:

Tick-borne bacterial infections include:

Other conditions sometimes caused by bacterial infection include:

What tests should be done?

Laboratory tests for bacterial infections may include:

How are bacterial infections treated?

Minor bacterial infections may resolve without treatment. However, persistent and serious bacterial infections are treated with antibiotics. These are available for localised topical use (creams, gels, solutions), eg antibiotics for acne, or as systemic treatment as tablets, capsules and intramuscular or intravenous injections.

It is best to take samples to test which organism is responsible for an infection before commencing antibiotics. If the infection is serious (eg meningococcal disease is suspected), immediate treatment with broad-spectrum antibiotic may commence. Once the specific organism causing infection has been determined, the antibiotic may be changed to a narrow-spectrum antibiotic directed against this organism.

Antibiotics have important individual risks and societal impact and should not be prescribed or taken if they are not required or if they are unlikely to be of benefit, for example if infection is viral in origin.

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