Antibiotics are chemical compounds, which are safe and effective drugs that treat bacterial infections. They can be divided into two separate groups, bactericidal and bacteriostatic. Bactericidal antibiotics simply destroy the micro-organisms they target, whereas bacteriostatic antibiotics do not destroy the micro-organism but prevents them from multiplying but inhibiting their growth and reproduction, enabling the immune system to overcome the infectious bacteria. The one thing that all the different types of antibiotic have in common is their definition, which is "an antibiotic is a substance which is produced by one type of micro-organism which kills or stops the growth of another" (Indge, 2003).
Bacteria destroying compounds can be found in some plants, insects and amphibians. Antibiotics are mainly all produced from microorganisms, usually in the form of bacteria or fungi, although this is now becoming complicated because chemists can alter the structure of naturally found bacteria to increase its effectiveness. An example of naturally found bacteria that has been changed (semi-synthetic bacteria) is the antibiotic penicillin. Penicillin is now used worldwide for many different bacterial infections.
In 1928 a bacteriologist called Alexander Fleming, made a discovery which would ultimately make him the founder of modern day antibiotics. One day Fleming forgot to cover one of his dishes in which he was growing bacteria and the next day he found that the bacterial colonies inside this one dish had been killed. After a lot of searching he found that his bacteria had been destroyed by a blue/green mould. He identified this mould to be penicillium notatum, which is a mould that grows on the surface of fruit, and he realised that this mould must have produced a chemical substance which destroyed the bacteria. From this realisation, Fleming discovered a bacterial fighting substance which is today known as Penicillin. Although Fleming discovered this substance, it was not until 12 years later two Oxford scientists, Ernst Chain and Howard Florey, managed to isolate and purify the penicillin and thus discovered the importance of this antibiotic (MacKean, 2000).
Since the 1940's antibiotics have saved millions of lives, they are mostly harmless to humans as the biochemical reactions that they target in bacteria are different to that in animals. Even though antibiotics can be very effective in destroying bacteria, and that the war against bacteria seemed to have been won, in the 1960s they found that the bacteria were finding a way to fight back. Some strains of bacteria have arisen that are causing infections that are very difficult to treat, as they no longer respond to an antibiotic for example, MRSA (methicillin-resistant Staphylococcus aureus). This has become a topic that has caused a lot of controversy and panic, and is known as antibiotic resistance.
Bacterial infections are becoming more and more common and have become a major health threat to the population. It will also become the biggest heath threat if nothing is done about antibiotic-resistant bacteria. Antibiotics are no longer considered to be the super drug that they used to be simply because, even though the majority of bacteria are destroyed by an antibiotic, it takes just one antibiotic resistant bacterium to have a gene mutation that will enable it to survive and replicate with other germs. This resistance would then be passed on to the antibiotic. Bacteria exchange antibiotic resistant genes by passing plasmids that contain the genes, from one bacterium to another.
A bacterium becomes resistant to an antibiotic when one of its alleles becomes altered. There are four ways that this can lead to resistance.
first is where the altered allele occurs in the gene which codes for the protein that is a target for the antibiotic. If the altered protein is a different shape, it can no longer bond to the antibiotic. Thus if there is no binding, the antibiotic can have no effect on the bacterium.
The second mechanism is where antibiotic-resistant bacteria stop the antibiotic reaching its target molecule inside the cell, by either preventing the antibiotic from entering the cell, or by pumping it out faster than it can get in. This can happen if the mutation occurs in an allele that codes for a membrane receptor or transport protein.
The third mechanism is where the target of an antibiotic is an enzyme. Bacteria that produce an alternative version of the enzyme can bypass the antibiotic. This enzyme would still carry out the same function as would originally, but the antibiotic does not have any affect on it. Having both forms of the same enzyme gives the bacteria a distinct advantage, as it can survive equally well whether or not the antibiotic is present.
The fourth mechanism is where a mutation might enable the bacterium to produce an altered enzyme that is then able to react with the antibiotic and disable it.
The worldwide issue over the overuse of antibiotics is the foundation and plays the main role in the serious situation of antibiotic resistance. Individuals need to start realising that our bodies contain good bacteria and that this good bacteria has the capabilities and is strong enough to fight off other bacteria, such as pathogenic bacteria. The overuse of these antibiotics are primarily a result from GP's over prescribing antibiotics, or by prescribing antibiotics when they are not required. Other issues that contribute to the overuse of antibiotics is that many individuals do not complete the course of antibiotics of which they were supplied. These individuals simply stop taking their prescribed antibiotics when they start to feel well again, this allows the bacteria, with even a slight resistance, to re-establish an infection.
Farmers are also making a contribution to the resistance of antibiotics, by overusing agricultural antibiotics, as there are no limits to the amount that they can use. The bacteria that are being used on animals and plants, for growing purposes, are becoming harmful to the humans as the food that they are eating is becoming infected with these, such as Salmonella.
In conclusion, it can be said that antibiotic-resistant bacteria have an impact on the environment as a whole. Antibiotic-resistance cannot be overturned without the help of the patients, GP's, farmers, and the health officials. Each and every day, more and more bacteria are becoming resistant to antibiotics and if this issue is not sorted, the infections that result from these bacteria could lead to death.
MacKean, D., (2000) Life Study - A Textbook of Biology. UK: John Murray (Publishers) Ltd.