Antibiotics are a group of drugs used to treat
various infections caused by bacteria. The first antibiotic was discovered by
Sir Alexander Fleming in 1928 in a significant breakthrough for medical science.
The development of antibiotics is probably the largest advance in medicine in
the 20th century, and has saved millions of lives worldwide from
infections such as TB.
Since Fleming's original development of penicillin,
a wide range of antibiotics has been developed. Originally produced from moulds
and fungi, many antibiotics are now produced synthetically.
Antibiotics are not effective against infections
caused by viruses, so if you go to your doctor with a viral illness such as
a cold, flu or a viral sore throat, antibiotics have little or no role to play.
Some antibiotics are effective only against specific
bacteria. For example, if you have a streptococcal throat, penicillin may be
prescribed. Others are effective against a wide range of bacteria. These are
called broad spectrum antibiotics. This type of antibiotic is often used to
treat respiratory or urinary tract infections because it is difficult to establish
what specific bacteria are causing the condition.
Antibiotics can be classified into five main categories:
PENICILLINS: eg. Amoxycillin, Amoxil, Augmentin,
Calvepen, Clonamox, Floxapen
CEPHALOSPORINS: eg. Cefodox, Distaclor, Keflex,
AMINOGLYCOSIDES: eg. Genticin
TETRACYCLINES: eg. Clinimycin, Hostacycline, Minocin,
OTHERS: eg. Ciproxin, Erymax, Erythrocin, Flagyl,
Ipral, Klacid, Zithromax
The choice of antibiotic depends on the type of
bacteria, the site of infection, the general health of the individual and any
history of allergic reaction to antibiotics.
Antibiotics may be taken as tablets, capsules,
liquids, creams or in intravenous infusions (directly into the veins through
a drip). Doctors recommend an antibiotic based on where the infection is, the
type of infection, the general health of the individual and the antibiotic being
do antibiotics work?
There are many
different antibiotics and they work in different ways. Essentially, antibiotic
drugs either kill bacteria (these are known as bactericidal) or stop bacterial
growth, allowing the bodys immune system to deal with the infection (these
are known as bacteriostatic).
The most commonly used antibiotics, penicillins
and cephalosporins, are bactericidal and work by breaking down the cell walls
are the dangers of inappropriate use?
Bacteria are capable
of developing resistance to a previously effective antibiotic drug. This means
that the specific antibiotic will no longer be of use in treating that infection.
While resistance may develop in any case, a number of factors may speed up the
development of resistance. These include:
Widespread use of antibiotics to treat relatively
minor infections in humans
Widespread use of antibiotics in the rearing
of animals which provide meat which is eaten by humans
Failure to complete a course of antibiotics
as prescribed by your doctor.
The danger of widespread resistance to antibiotics
is that bacterial infections will become untreatable and resistant strains of
bacteria will develop which will not respond to antibiotic treatment (so-called
'superbugs'). This will have serious consequences, initially for people with
underlying medical conditions such as chronic lung disease or diseases which
suppress the immune system, such as HIV.
There is huge concern among doctors that eventually
these 'superbugs' could cause untreatable infections in the otherwise healthy
There is considerable concern in Ireland at present
about the emergence of a type of infection which is resistant to methicillin,
one of the most powerful antibiotics available. The infection, known as MRSA,
thrives in hospitals, where people are in close proximity and may have their
defences weakened by illness.
MRSA is a growing problem worldwide. One of the
issues being stressed to health workers in hospitals is the importance of thorough
and frequent hand washing to avoid spreading the disease from patient to patient.
In Dublin, St James's Hospital was forced to close its Bone Marrow Transplant
Unit in September 2000 following an outbreak of Vancomycin-Resistant Enterococcus
(VRE), another dangerous antibiotic-resistant bacteria.
are the possible side effects of antibiotics?
can literally save lives and are effective in treating illnesses caused by bacterial
infections when appropriately used. However, like all drugs, they have the potential
to cause undesirable side effects. Many of these side effects are not dangerous,
although they can make life miserable while the drug is being taken.
Most antibiotic drugs have the potential to cause
nausea, vomiting or diarrhoea because they alter the normal balance of beneficial
or 'friendly' bacteria that live in the gut. Alteration of this balance between
certain types of bacteria and fungi in the body may also cause proliferation
of particular yeasts in the body, causing thrush in the mouth, gut or vagina.
Antibiotics may also cause skin rashes.
Other, less common, side effects may be caused
by particular antibiotics. Your doctor will warn you of these if you need to
take these antibiotics.
If you develop side effects, it is not wise just
to stop taking the antibiotic. You should consult your doctor to discuss whether
specific treatment of the side effects are needed or whether you should be changed
to another antibiotic to treat the initial infection.
do I know if I am allergic to an antibiotic?
Some people may
be allergic to a particular class of antibiotics. If this is the case, these
antibiotics should be avoided in the future and other antibiotics, from different
categories, should be used to treat bacterial infections.
Allergic reactions cause swelling of the face,
itching and a skin rash and, in severe cases, breathing difficulties. Allergic
reactions require prompt treatment. This will include stopping the antibiotic
and possibly taking anti-histamine drugs. Hospital admission may be necessary
in severe cases.
Many people may believe they are allergic to an
antibiotic if they develop vomiting, diarrhoea or a skin rash when taking an
antibiotic. These symptoms are not caused by an allergy to the antibiotic, but
are side effects of the drug. Side effects occur more commonly than allergic
The distinction is important because of its consequences
for future treatment. If you develop side effects, then you should avoid that
particular antibiotic in the future but you may be able to tolerate other antibiotics
from the same class eg. if you develop side effects when taking one penicillin,
you may well tolerate other penicillins in the future. However, if you are allergic
to a particular penicillin you should avoid all penicillins (and also cephalosporins).
special precautions are needed in taking antibiotics?
Your doctor will
be aware of the special precautions in prescribing antibiotics if you have chronic
liver of kidney disease. It is important to tell your doctor if you have a history
of allergy to an antibiotic or have experienced side effects from an antibiotic.
Some antibiotics are best avoided by women who are pregnant or breast feeding.
You should inform your doctor of all other medications you are taking at the
time as antibiotics can interact with other medications, particularly the oral
How long should a course of antibiotics last?
The choice of antibiotic, the dose and the length
of the course will depend on the infection being treated and the general health
of the person. Your doctor will prescribe the appropriate course for the particular
illness. It is important to complete the course as prescribed to ensure that
the illness is treated properly. Failure to complete antibiotic courses is also
a contributory factor to antibiotic resistance.
Courses may be as short as a single dose of an
antibiotic. Three or five day courses of antibiotics are commonly recommended
for urinary tract infections. Bacterial infections of the throat or lungs may
require between five and 10 days' treatment. Long-term antibiotics (for months)
may be prescribed in the treatment of acne or the prevention of recurrent urinary