Sample Essay on Advantages of Antibiotics

In 1928 Alexander Fleming after coming home from holiday found (whilst sorting out glass plates with the bacteria staphylococcus) that one of the plates had a blue/green mould on it. It had a clear ring around it where the bacteria had been dissolved. The mould was penicillium notatum. Fleming after some research came to conclusion that a substance coming from the mould must have killed the bacteria, an antibiotic. The discovery was not noticed at the time, as it was extremely hard to isolate the penicillin but it’s potential was there.

Just as the Second World War had started two Oxford scientists managed to isolate and purify the penicillin in a new interest in the field of anti-bacterial drugs, this was because of the up and coming war. A programme in the USA saw the mass production and distribution of the drug it was known as the “wonder” drug amongst soldiers. The extreme effectiveness of antibiotics in destroying harmful bacteria is such a big advantage in using antibiotics, but the chance that one bacterium may have the resistance gene means resistance can be a huge problem.

But in contrast it has been found that the effectiveness of antibiotics can help many in their fight against cancer, with the use of chemotherapy. Since 1940s antibiotics have saved millions of lives, they can kill bacteria by preventing its peptidoglycans from synthesising, making the cell burst. Antibiotics are mostly harmless to humans as the biochemical reactions they target in bacteria are different than in animals.

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The New Scientist article source by Alison George describes the three modes of attack of antibiotics on bacterium.

The first has already been described above (cell bursts due to effect on protein synthesis. ) The second form of attack is in targeting the DNA of bacterium by damaging its base sequence therefore the DNA cannot multiply and grow, this is called a mutation. The damaging of the DNA can be due to deletion (loss of bases from sequence,) insertion (addition of bases to sequence) or substitution (when one or more bases are swapped. ) The third type of attack is aimed at the cell wall, the antibiotic vancomycin attaches to the substrate needed for cross-linking molecules in the cell wall.

This then deforms the substrate and this then leads to the specific enzyme that has a complementary active site not being able to attach to substrate, enzyme-substrate (e-s) complexes cannot form. It acts as a competitive inhibitor and may be a temporary way of damaging the cell call. The other way antibiotics can affect the cell wall of bacterium is by blocking the cross linking enzyme. Antibiotics such as penicillin, methicillin and flucloxacillin either compete for the same substrate therefore reducing the number of e-s complexes or break the hydrogen bonds of the enzyme’s tertiary structure.

Which will in turn deform the shape of the active site meaning it will not fit the substrate, leading to no e-s complexes being formed. When this happens the enzyme is said to be “de-natured” and this cannot be reversed. Even though antibiotics can be very effective in destroying bacteria, and the war against bacteria seemed to have been won they found in the 1960s that the bacteria were finding a way to fight back. A topic that has caused a lot of controversy and panic is the resistance of bacteria to antibiotics.

As Clegg describes in his Introduction to Advanced Biology there are two ways in which bacteria can resist antibiotic effects. The first to look at is the spontaneous mutation of a gene that gives the offspring new abilities in fighting back against antibiotics. This can be due to the over use of antibiotics causing the evolution of bacteria to become resistant to these antibiotics, as described by the UK’s Food Commission web-page on the topic.

The other way described by Clegg was the transfer of the resistant gene between bacteria due to conjunction (form of sexual reproduction. ) The resistance discussed by Jones, M and Jones, G can be applied the bacteria’s natural cell wall structure being too complex for the antibiotic to enter or the slowing of the antibiotics entry and then breaking the antibiotic down by enzymes in the cell or another possible resistance process were a specific protein in cell membrane pumps the antibiotic out of the bacteria once it enters.

There is also a last possible method of resistance, which is the hydrolysis of antibiotics inside some resistant bacteria. There is a type of resistant bacteria that has cause a lot of controversy in the national newspapers throughout the world. It is MRSA (Multiple resistant Staphylococcus aureus. ) Its resistance has been put very well in the New Scientist article, “bacteria pick up resistance to new antibiotics and retain resistance they already have. Eventually they can build up resistance to most – if not all – antibiotics used against them.

Although the resistance of antibiotics causes a lot of worry and controversy over the use of antibiotics, an argument of advantages to the use can put be forward through the successful treatment of chemotherapy. This process goes beyond the efforts of natural and artificial methods of destroying disease-causing microorganisms. Which the body’s defence mechanism can be avoided by. It is the administration of chemical substances, natural or synthetic than kill/prevent reproduction of microorganisms by the inhibition of dividing malignant cells in cancer.

These substances are classed as antibiotics as some of the substances are secreted by microorganisms and are selectively toxic to other microorganisms. Although these chemotherapeutic agents have had an enormous influence in controlling disease they have a major disadvantage. Every time a new one is used, resistant strains arise so further drugs have to be developed and produced. These new drugs should be used with restraint and discrimination according to Roberts, Reiss and Monger’s Chemotherapy and antibiotics section of their Biology Principles and Processes textbook.