Virus, Bacteria - How do Antibiotics work?

My Dear Sniffy, still Sexy though, Readers,

By this time, you probably have all suffered from the sore throat that prevents you from sleeping or the cough that seems to empty your lungs, the sinuses under immense pressure that make your eyes watery, the sneezing, the shivering, the headaches, etc...

So naturally, you call your doctor/GP/clinic and request an urgent appointment because, quite honestly, you feel so shit, it can't be normal, you need medicines, and lots of them!!!

How many times, then, didn't I hear "my GP is crap, he only gave me paracetamol!", "I went to see another one, he gave me antibiotics, so see? The first one is obviously not qualified".
Yes, it's true, in the UK, your GP won't tell you to take some guafenisin, imodium or motilium or suck on Strepsils like doctors do 'on the continent' and you need to seek advice at the Pharmacy or on Google.
Although I don't particularly agree with the kind of self medication policy in this country, it does help to dis-engorge clinics for more serious cases.
So in case you wonder, here is a factsheet on bacteria and viruses and why there's no point taking Antibiotics when you have a cold:

Note: If you don't feel like reading, why not check my Pinterest infographic, just hover your pointer over here.

Note2: Ever wondered how Amoxicillin works, check it out in our Did You know Series!

What's the difference between virus and bacteria?
When do we need antibiotics?

Bacteria

A bacterium is a single cell microbe. The content of this single cell is much simpler than the content of a human cell. For example, because their DNA is not contained in a defined vesicle, they are called prokaryotes. As opposed to our eukaryotic cells where the DNA is contained inside the nucleus.

They are categorised according to the fact that they have an outer membrane or not  (gram negative or positive respectively) and to their shape (spheres, rods, spirals, commas and corkscrews).

Their size can vary from 50 nm (0.05 micrometers = 0.00005 centimeters) to 2 micrometers in diameter or width for the spherical ones and from 1 to 10 micrometers for the long one.

(A micrometer is the size of a pin head, it is also 10 times smaller than a centimeter)

How do bacteria infect our body and what does the body do about it?

Bacteria love our bodies, our fluids are so rich in vitamins, sugars and other nutrients, they can find everything in there to grow and survive. We can be infected by bacteria by contact with them, through infected water, food, dust, air liquid droplets or through our wounds for example.

The points of entry are also our natural barriers such as our skin when we are sweating, our eyes and lacrymal glands, our nose and our nasal hair and the runny nose; and if through the mouth, the acidity of our stomach or the natural bacterial flora from our intestines will fight for us.

Unfortunately, some of them are stronger than our first defences and will continue their invasion and stimulate therefore our second line of defence, our immunity.

Immunity

Our immunity can be triggered by different mechanisms and our defensers can be macrophages (they eat the invaders and take a sample to show the rest of our defense lines what the body is fighting against), phagocytes (they are whole cells whose job is to eat the invaders), cytokines (messengers that will warn the rest of the immunity who's the culprit) or lymphocytes (cells that will fight the invaders or will control the cells that will fight the baddies). They will work altogether, sort of like -community officers - police officers - the army- would.

Following an infection, the signs are: The tissues in the area are red and warm, as a result of the large amount of blood reaching the site. They are also swollen, again due to the increased amount of blood and proteins that are present. The area is painful, due the expansion of tissues, causing mechanical pressure on nearby nerve cells, and also due to the presence of pain mediators.

The battle ends when all phagocytes have eaten and digested all the invaders. You can see their action when you are rejecting the pus or mucus - of different shades, depending on who's at fault!

Virus

Virus particles (known as virions) consist of two or three parts: i) the genetic material made from either DNA or RNA, which are long molecules that carry genetic information; ii) a protein coat that protects these genes; and in some cases iii) an envelope of lipids that surrounds the protein coat when they are outside a cell.
The shapes of viruses range from simple helical and icosahedral forms to more complex structures.

Example of virus structure

In general, viruses are much smaller than bacteria. Most viruses that have been studied have a diameter between 20 and 300 nanometres. Some filoviruses have a total length of up to 1400nm; their diameters are only about 80nm.

How does a virus infect our body and what does the body do about it?
Through coughs, sneezes, vomit particles, bites from infected animals or insects, exposure to infected bodily fluids, a virus can enter our body.

Viruses can't multiply on their own, they have to invade a 'host' cell and take over its machinery in order to be able to make more virus particles: they consist of genetic materials (DNA or RNA) surrounded by a protective coat of protein. They are capable of latching onto cells and getting inside them, and making the host cell use their DNA to spread themselves (here below, a specific example with the HIV retrovirus).

The cells of the mucous membranes, such as those lining the respiratory passages that we breathe through, are particularly open to virus attacks because they are not covered by protective skin.

The human body does have some natural defenses against a virus. A cell can initiate RNA interference when it detects viral infection, which works by decreasing the influence of the virus's genetic material in relation to the cell's usual material. The immune system also kicks into gear when it identifies a virus by producing antibodies that bind to the virus and render it unable to replicate. The immune system also releases T-cells, which work to kill the virus.

How do Antibiotics work?

Antibiotics are given as anti-bacteria medicine. They either kill the bacteria or stop the multiplication of bacteria. They are also working against parasites and fungi.
Choosing an antibiotic will kill the desired bacteria, but not the cells in your body. Each different type of antibiotic affects different bacteria in different ways. For example, an antibiotic might inhibit a bacterium's ability to turn glucose into energy, or its ability to construct its cell wall. When this happens, the bacterium dies instead of reproducing. At the same time, the antibiotic acts only on the bacterium's cell-wall-building mechanism, not on a normal cell's.

Antibiotics do not work on viruses because viruses are not alive. A bacterium is a living, reproducing lifeform. A virus is just a piece of DNA inserted into a living cell to reproduce more of the viral DNA. Therefore, there is nothing to "kill".

Bacterial resistance to Antibiotics

The most serious concern with antibiotic resistance is that some bacteria have become resistant to almost all of the easily available antibiotics. These bacteria are able to cause serious disease and this is a major public health problem. Important examples are methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and multi-drug-resistant Mycobacterium tuberculosis (MDR-TB).

What to do to prevent Antibiotic resistance?

Solutions are to minimise unnecessary prescribing and overprescribing of antibiotics for example. Making sure to complete the entire course of the prescribed antibiotic is important so that it can be fully effective and not breed resistance. And of course, we must practise good hygiene and use appropriate infection control procedures.

See you Soon for more Sexy, less Sniffy, Science,

References
http://www.humanillnesses.com/original/At-Ca/Bacterial-Infections.html
http://health.howstuffworks.com/medicine/medication/question88.htm
http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Infections_bacterial_and_viral