26/09/2017 10:06 BST | Updated 26/09/2017 10:06 BST

A Guide To... Antibiotics

Simply put, antibiotics are types of chemicals that kill bacteria.

Bacteria is a type of micro-organism that live all around us and even inside us (our gut contains trillions of bacteria), and normally don't cause any problems. When certain types of bacteria get inside our bodies they produce toxins that damage our cells or prevent certain parts of our bodies working properly and this causes disease. Bacteria are responsible for some of the most severe diseases that can affect people, including meningitis, sepsis, and tuberculosis.

Centuries ago, the Black Death wiped out over 30% of the European population because of a disease spread by bacteria. Before antibiotics were discovered, if someone had a bacterial infection there was very little doctors could do to treat them, so people would get seriously ill or even die from diseases that seem quite trivial today.

How do antibiotics work?

There are many different ways in which antibiotics work. Penicillin was the first antibiotic discovered (in the 1940s) and this works by damaging the cell wall of bacteria. The cell wall is the outer casing of a bacterium that protects it from the outside world and controls what goes in and out of the cell, so damaging it essentially causes the cell to burst.

Since then many new types of antibiotics have been discovered and work in different ways; for example, some other antibiotics will damage the DNA of the bacteria, while others will prevent bacteria from making vital parts of their cells.

Some antibiotics are very effective against bacteria, while others may be useless, it just depends on the 'machinery' of the bacteria. Luckily, we have enough different types of antibiotic to tackle every type of bacteria (well, almost, but we'll come to that later...).

Do I need antibiotics?

Many people go to the doctor with an illness in the hope of getting antibiotics to clear it up, but not all will leave with the prescription they wanted. Why?

Simply put, if it's not a bacterial infection, antibiotics are unlikely to help. Illnesses like the common cold and flu are caused by viruses, and antibiotics have absolutely no effect on viruses and could actually make you feel worse!

Many medicines have side effects, and antibiotics are no exception, with side effects ranging from mild and annoying to serious and even life threatening (fortunately these are very rare).

So, while your cold may be annoying, sadly there's not much doctors can do about it; however, if your symptoms don't go away after a few days or gets worse, then you should go to your GP just to be sure it is a mild viral illness and nothing more serious.

What is antibiotic resistance?

There has been a lot in the news over recent months about 'the rise of antibiotic resistance' which is when bacterium find ways to avoid being killed.

For example, some antibiotics have to get inside bacteria to kill them, but if bacteria can make themselves impenetrable to the antibiotic or create a way to pump it out, antibiotics won't work.

Resistant bacteria (often known as 'superbugs') can pass resistance on as it multiplies, and can even directly transfer the resistance genes to other bacteria. This means even one resistant bacterium can quickly give rise to millions of resistant bacteria, none of which are effected by the antibiotic that would usually be used to treat them.

If these bacteria are just causing a minor infection then this may not be too bad, but if they are causing something more serious this can be lethal; indeed, the CDC estimates that 23,000 people die in America every year from resistant infections, and this number is rising.

Even more worrying than bacteria resistant to a single antibiotic are bacteria that have become resistant to multiple antibiotics. Recently, an American woman died after she became infected with a type of bacteria known as Klebsiella that was resistant to not one, not two, but twenty-six different antibiotics. She died because this made it completely incurable.

What can be done about resistance?

Antibiotic resistance is pretty scary, but there are things that can be done to slow its development. The fewer antibiotics are used, the less likely bacteria are to become resistant to them; they can't evolve to resist something they've never been exposed to.

Over the years, some doctors have been guilty of over-prescribing antibiotics too, and there is now a lot of pressure on doctors to avoid doing this - another reason your GP shouldn't give you antibiotics for just a sore throat or cold.

One thing that you can do is make sure you take any antibiotics you are prescribed properly! It is vital to take the full course of any antibiotics you are prescribed, even if you feel better before the course is over. Taking less than the full course won't kill enough bacteria, and the bacteria that remain will have been exposed to the antibiotic so are more likely to become resistant.

Ultimately, these things will only slow down the development of resistance, and eventually we're going to need new ways to kill bacteria. Luckily, there is a lot of research going into this, including looking for new antibiotics and trying to find other weird and wonderful ways to kill them.

Antibiotics have completely revolutionised medicine: they have saved millions of lives and made many deadly conditions highly treatable.

Currently, they are very effective against most bacteria, but superbugs such as MRSA are on the rise. Good understanding of proper antibiotic use both by the public and by doctors, is vital to slow down the development of resistance and ensure these drugs stay effective for as long as possible.

Dr Seth Rankin is founder of London Doctors Clinic