The Effectiveness Of Antimicrobial Agents Biology Essay

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Bacteria need warm and moist surroundings to be able to reproduce. They can either reproduce by the process of asexual reproduction where they are split up into two or by cell division, a process called: binary fission. Binary Fission takes place in a bacteria cell when DNA replicates and then divides into two identical cells.

The main difference between the two types of gram positive and gram negative bacteria is the makeup of their cell walls. The cell wall of the gram positive bacteria consists of a very thick layer of peptidoglycan, formed by a chain of amino acids whereas; the gram negative cell wall contains a thinner peptidoglycan with a multilayered outer membrane that is made up of substances such as: phospholipids.

The process of gram staining is used to determine the two types of bacteria. During this process, both bacterial cell walls are exposed to a crystal violet dye. After the gram positive bacteria is decolourised it turns purple to show the peptidoglcan's ability to decoy the dye; likewise, the gram negative's multilayered outer membrane encourages it's inadequacy to absorb the dye; It does not allow the dye to envelope its thin peptidoglcan layer, so the cell wall turns pink when decolourised with ethanol.

As mentioned earlier, gram-positive and gram negative bacterial cell walls consist of different structures made from the same protective layer, called: peptidoglycan. The peptidoglycan layer is vital for the bacteria's survival in anesthetic surroundings; any deficiency or corruption, will not only destroy the cell's inflexibility but it will consequently kill the cell.

The gram positive bacteria contain a thick layer that traps substances and the gram negative bacteria have a thin layer which is surrounded by a plasma membrane that prevents the absorption of substances.

Based on the analysis of the different cell walls, it was determined from the results of the experiment that some antibiotics and antimicrobial inhibitors will kill, grow or render the gram positive and gram negative bacteria by interrupting the structures of their cell walls.

If we take a look at some of the results in the table, we can see that the gram positive bacterial cell wall was targeted by four different antibiotics along with all three types of antimicrobials. Comparing this to the gram negative bacteria, we find that there are fewer targets; only three types of antibiotics and one antimicrobial managed to work. This sums up that the gram negative bacteria are in most cases, more resistant to antibiotics than the gram positive bacteria.

Although, they both have cell membranes; the structures of the cell membranes will still allow substances to pass through into the cell, but in saying so, the distinct outer membrane which envelope the gram negative bacteria prohibits any antimicrobials or antibiotics from accessing the cytoplasm of the cell.

As a typical scenario, there are two types of infections which fit in the two categories of gram positive and gram negative bacteria, these include: Klebsiella and Enterococci.

Klebsiella is a gram negative bacteria that develops in humans and animals as normal flora, within the digestive system and other parts of the body. However, when these bacteria travel outside to invade vital organ systems such as the respiratory and urinary systems, they cause serious infections of the lungs such as: bronchitis and infections of wounds, which might be going through the process of healing.

Most Klebsiella infections are more likely to happen in places where there is constant interaction with others such as: hospitals or care homes. In case of a serious epidemic of Klebsiella within a care home, the strongest antibiotics that could be used to treat the infections based on the results might include: Chloramphenicol (C), Streptomycin (S) and Tetracycline (T), because these have a higher range of activity within this category needed for this category. For example, streptomycin which is made up of different antibiotics will stop the cell from making protein by creating cracks in the outer membrane of the cell and travelling into the thin layer of peptidoglycan.

In contrary to this, Enterococci are gram positive bacteria that can also be useful to humans and animals as part of normal flora within the digestive system; intestines and the stomach. In serious conditions where the immune system is weakened due to illness, the Enterococci Bacteria will multiply to attack vital organ systems such as the urinary system; causing abnormal pains and damage to the kidneys.

The antibiotics that could possibly treat an Enterococci outbreak in an old people's home are: Erythromycin (E), Streptomycin (S), Chloramphenicol (C) and Tetracycline (T) because they can easily demolish the thick layer of peptidoglycan and get into the cytoplasm of the cell.


Sections C and D

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Task 3 M1

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Task 4 D1