Mutations and Resistance
Our bodies are wonderfully well adapted to fight infections, and generally we are pretty efficient at at either intercepting or overcoming the tiny microbes that cause illness, called pathogens. Unfortunately there are times when our body either doesn't recognise a pathogen or simply can't do anything about it, and we do get ill.
Our basic methods of preventing illness are:
1. Our skin
Skin is a highly effective barrier to pathogens and were it not for our lovely layers of the stuff we would be open to all sorts of infections. Problems arise when we have cuts or grazes that allow pathogens to enter our body and wreak havoc. It is why you should always wash out a fresh cut and protect it until it has healed over.
2. Our tears
When we get something in our eyes they water immediately, whether we like it or not. This autonomic response is designed to flush out anything that gets into our eyes, that could cause an infection. Tears also contain an enzyme called lysozyme to break down bacterial cell membranes.
3. Our noses
You will be familiar with this one; our noses run when we have a cold, partly because of inflammation of the soft tissue, but also as a way to flush out microbes that may be pathogens. This is the basis of sneezing too.This isn't the only way our noses protect us, they also have tiny little hairs that trap airborne pollutants and pathogens.
Often occurring at the same time as a runny nose, this irritating defence mechanism is designed to expel would be invaders from our lungs. Sadly it also has the side effect of transferring them to the air around us for some other lucky person to inhale.
5. Stomach upset (Sickness and Diarrhoea)
Another unpleasant reaction of our body to microbes (bacteria or viruses)! If you're really unlucky these will happen together as your body tries to eject whatever it is that has entered your body. Diarrhoea is a major cause of death in underdeveloped countries (LEDC) because of lack of access to clean water.
If 1-5 weren't effective enough at overcoming pathogens our bodies can turn up the thermostat and try to damage the pathogens through heat. When we get a fever it is our response to a pathogen, and is the reason why doctors will take your temperature to see if you're ill. Normal body temperature is 37oC, but it can rise to 40oC if we are really unwell. Temperatures this high can be fatal.
If you're a conspiracy theorist, you'll think that drugs companies HAVE found a cure for the common cold, but they won't release it because they make so much money from cold and flu remedies (Lemsip/Beechams etc). However, if you're not, then you'll know that the common cold is a cunning little virus that has the ability to mutate quite easily. The virus has a protein coat around it, and if you like visual images then just think of a tiny little bug wrapped up all snug in a blue coat.
Normally our immune system is really good at recognising pathogens, and so long as it's met it before then it will start producing antibodies (this is the basis of vaccination). However, the cold virus is capable of changing it's protein coat to fool our immune system. This is a little bit like not being allowed into a venue and then sneaking back with with a disguise on (Not that I've ever done that but it works as a model!).
Now, this mutation is a pain, as I'm sure you're aware because it means that we catch colds quite easily.
However, there is a much more alarming aspect to all of this. It's not just cold viruses that can mutate.
There is a relatively recent mutation that has occurred which is causing some concern amongst medical professionals. There is a bacteria called Staphylococcus Aureus (That's the SA bit of MRSA) that is responsible for all sorts of minor infections, such as sore throats and runny noses, although it can be much more harmful. This little bug is quite common and most of the time doesn't bother us, unless it gets out of control.
In the early 20th Century (so only about 100 years ago), by happy coincidence, a scientist called Alexander Fleming stumbled upon a mould formed in a petri dish, that seemed to be inhibiting the growth of bacteria. Further experimentation with the mould led him to discover that the mould, from which he extracted penicillin, was an antibiotic; i.e. it killed bacterial infection. His work continued and he discovered that even when he diluted it 800 times, it still worked. The first antibiotic was made, penicillin. This completely revolutionised medicine, with treatments for infections now available for the first time.
Fast forward about 50 years and not much has changed really. Doctors still prescribe penicillin (or one of it's close relatives; amoxicillin, methicillin etc.) for infections. There are some alternatives to penicillin based medicines but much of our antibiotic arsenal is now exhausted in the fight against infection, there just aren't new antibiotics being discovered.
I'm going to use a model to describe this, so get your brain warmed up for some slightly odd imagery.
If you've ever played a strategy game on your phone you'll get this bit quickly, but if you haven't I'll give you the full picture.
When our bodies are under attack from a pathogen the immune system responds by producing antibodies. These are white blood cells that are adapted to consume the bacteria/virus in the body. Because our body is cleve, it recognises infection that it has met before and produces an "army" of antibodies just for the specific infection.
Think of it like Boom Beach.
In Boom Beach you try to invade other players islands using your army. The islands have defences built to overcome attacks. If you attack an island with better defences then your army will be defeated, and vice versa. Your defences work best if you know the type of army invading, say if you've met them before. (It's a great game, you should try it*)
*other games are available
Anyway, back to our immune system.....
Some infections need to be treated with antibiotics to help our bodies to combat them. When doctors first started prescribing antibiotics it is thought that they "overprescribed" them, i.e. they gave them to people too easily. This meant that people were taking them even if they didn't really need them. It is also thought that patients often didn't finish the full course of antibiotics, so didn't completely eradicate the infection. A combination of both of these things led to some bacteria becoming resistant to antibiotics, so called Methicillin Resistant Staphylococcus Aureus (MRSA).
Click the link below to read what the NHS says about MRSA.
MRSA can't be treated with normal antibiotics, because it is resistant to them due to the mutation it has undergone. It is classed as a "superbug" and can be fatal.