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Reviewed by Dr Victoria Lewis, specialist
registrar in dermatology
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Why are they used?
The
bacteria Staphylococcus aureus can be found on most people’s
skin. However, on skin that is affected by atopic eczema,
increased numbers of these bacteria are found in over 90
per cent of cases. These bacteria seem to bind more
readily to skin that is inflamed, and can make the
inflammation worse because they secrete substances called
superantigens. These allergy-inducing substances activate
the immune cells in the skin, causing them to release
substances that further increase inflammation. Controlling
the number of these bacteria on the skin can help control
the eczema.
Skin affected by eczema
also has fewer defences against bacteria, viruses and
fungi than healthy skin, which can allow the numbers of
micro-organisms on the skin to increase. This predisposes
the skin to infection and is why scratching and breaking
the skin can often cause it to become infected. Infection
subsequently increases the inflammation.
Antimicrobials are used to treat infected
eczema.
Antimicrobials are also
included in some topical corticosteroid products
that are prescribed with the aim of helping to prevent
infection, for example in moist areas of skin where
infection is more likely, such as nappy rash, seborrhoeic
dermatitis, or inflamed areas where skin surfaces are in
contact (intertrigo), eg between the thighs or between the
buttocks. However, combined corticosteroid-antibiotic
products generally have no advantage over the
corticosteroid alone. They may also increase the risk of
skin sensitisation and encourage the growth of bacteria
that are resistant to the antibiotic.
How do I know if my eczema is
infected?
You should suspect that your
eczema is infected if it is crusting, weeping or producing
pus, if the eczema appears to suddenly get worse, or if
the surrounding normally healthy skin becomes red, hot and
swollen.
If you think your eczema is
infected it is important to consult your doctor so that
this can be confirmed and the infection treated. In the
meantime you should not use topical steroids as these can
allow the infection to spread. Sometimes your doctor may
want to take a swab from the infected area to identify the
organism that is causing the infection, as this will help
decide the most appropriate treatment.
What type of antimicrobials might
be prescribed?
The antimicrobials
used depend on the organism causing the infection and the
severity of the infection. Infections with bacteria, eg
Staphylococcus aureus, require antibiotics. Infections with
fungi or yeasts such as Candida albicans require
antifungal medicines. Infections with viruses such as
Herpes simplex require antiviral medicines.
Localised infections that are not too severe may
be treated with an antimicrobial cream, or a cream
containing a combination of corticosteroid and
antimicrobial. Topical antibiotics include fusidic acid,
neomycin, oxytetracyclin and mupirocin. Topical
antifungals include nystatin and econazole.
Moderate to more severe extensive infections may
require treatment by mouth, for example with a course of
antibiotic tablets. The most common oral antibiotics to be
prescribed for bacterially infected eczema are
flucloxacillin (a type of penicillin) or erythromycin. You
may also be prescribed a course of these if your eczema is
hard to control and skin swabs reveal large numbers of
Staphyllococcus aureus on your skin.
If your eczema becomes infected with the cold
sore virus (Herpes simplex) your doctor may prescribe a
course of aciclovir to be taken as a tablet or syrup. In
severe cases, the treatment should be given in hospital via
a drip.
Seborrhoeic eczema is
associated with the presence of the yeast Malassezia
furfur on the skin, and shampoos containing medicines that
are active against this yeast, for example ketoconazole
shampoo, may be used to treat this type of
eczema.
How
long should I use them for?
The
course prescribed to treat an infection may last from five
days up to two weeks. It is important that you finish the
course of antimicrobial unless otherwise advised by your
doctor, even if it seems the infection has cleared up.
Stopping the course early increases the chance that the
infection will come back and that the micro-organisms will
grow resistant to the medicine.
Are there any side effects?
Topical antimicrobials are unlikely to cause any
problems, though some people may occasionally find their
skin becomes over-sensitive or allergic to them. This is
more likely if the preparation is used for longer than
instructed by your doctor, or repeatedly for recurrent
infections.
The most common side
effects associated with oral antibiotics such as
flucloxacillin and erythromycin are stomach upsets such as
nausea, vomiting or diarrhoea.
You can get more information about possible side
effects from the patient information leaflet that will be
provided with your medicine.
Can I drink alcohol if I am prescribed
antibiotics?
It is a common
misconception that alcohol should be strictly avoided by
people who are taking a course of antibiotics. For certain
antibiotics this is the case, for example consuming alcohol
while taking a course of metronidazole can cause
unpleasant reactions and should be avoided. However, it is
safe to drink alcohol while taking a course of
flucloxacillin or erythromycin.
What if I’m taking other
medicines?
If you are taking a combined
oral contraceptive pill and are prescribed a course of
oral antibiotics there is a very low risk that the
antibiotic may make your pill less effective at preventing
pregnancy. For this reason you should use an additional
barrier method of contraception, eg a condom, both during
the antibiotic course and for seven days after finishing
the antibiotic.
Always tell your
doctor or pharmacist what other medicines you are taking,
including those bought without a prescription and herbal
medicines, when you are prescribed a new
medicine.
How
can I avoid infections?
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Don’t leave the any of your creams, lotions,
etc open, as this makes them more likely to become
contaminated with bacteria. For the same reason it
may be worthwhile to use a clean spoon to remove creams
from tubs or jars. Pump dispensers may also be
useful.
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Always wash your hands before
applying creams, etc to the skin.
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Using bath additives or moisturisers that contain
antiseptics can help prevent infection by killing
the bacteria found on the skin.
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Try not to scratch your eczema as this helps
micro-organisms to penetrate the skin.
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Keep your nails short.
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Wearing cotton gloves at night can help stop
yourself scratching in your sleep.
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Based on a text by Helen Marshall, pharmacist
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Last updated 10.04.2007
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