Investigating the effect of sodium chloride on the action of antibiotics on bacteria growth

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Investigating the effect of sodium chloride on the action of antibiotics on bacteria growth

Abstract

Effect of sodium chloride on the action of antibiotics on bacteria growth was investigated using Escherichia coli with antibiotic penicillin. Sodium chloride delayed the size of area of bacteria growth with increasing concentration of sodium chloride for incubations at 25ºC. from statistical and graphical analysis growth inhibition indicates that antimicrobial activity is correlated with the concentration of sodium chloride. This was proven to be the case with a null hypothesis testing at 5% significance level was rejected.


Aim

To investigate how varying concentration of sodium chloride affect the action of antibiotic on bacteria growth by measuring the area of bacteria growth inhibition around the antibiotic discs on an agar plate.

Rationale

Cystic fibrosis is one of the most commonly inherited diseases in Europe affecting at least 1 in 20 persons. [1]“It is an autosomal recessive condition whereby two alleles carrying a polymorphism in the cystic fibrosis transmembrane conductance regulator (CFTR) gene” fails to function properly due to mutation in the gene.

Fig 1 shows the structure of cystic fibrosis transmembrane regulator (CFTR)

The CFTR protein may be missing and if present does not function correctly. When there is too little water in the mucus, chloride ions cannot be secreted across the apical membrane and there is no blockage of the epithelial sodium ion channel. Since the sodium ion channels are constantly open there is a continual absorption of sodium ions by the epithelial cells. The raised level of sodium and chloride ion cause a difference in concentration gradient and water is drawn out of the mucus into the cell. This cause the mucus to become more viscous, causing difficulty for the beating cilia to move. As a result the mucus is not effectively removed from the lungs causing build up of sticky mucus in the nasal passage. This mucus frequently becomes infected with bacteria. Chronic Upper respiratory tract infection caused by pathogens is one of the most common complications of cystic fibrosis usually caused by bacterial pathogens. Chronic lung infection caused by bacteria leads to cardiopulmonary deterioration which is a major cause of death in cystic fibrosis patients

Immune response is the action taken by the body to destroy invading pathogens. Non specific immune response involves the destruction of invading pathogens and foreign body. White blood cells damaged by pathogen are found in connective tissue around blood vessel. They release histamine which causes the dilation of arterioles at the site of infection to increase blood flow and the number of white blood cells ready to attack. Phagocytes are white blood cells that engulf bacteria in blood and tissue fluid. Neutrophil and monocytes are types of white blood cells. Non specific immune response is a type of immune response that is directed at a specific pathogen. Lymphocyte is a type of white blood cell that helps defend the body against specific pathogens. The two types of lymphocyte (B cells and T cells) respond to antigen molecules on the pathogen. They secret antibodies which respond to the antigens.

 As part of an immune response, natural antimicrobial proteins (lysozyme) in the nose are secreted to kill bacteria that accumulate by breaking down the cell walls. Unfortunately the ability of this enzyme to function to its maximum potential is often reduced in cystic fibrosis patients. This is thought to be as a result of the high concentration of sodium chloride ions in the lungs/ in areas of mucus accumulation.

     [4]“Escherichia coli are Gram-negative bacteria that belong to the g-proteobacteria. They primarily live in the mammalian gut. They are part of a group of bacteria known as enteric bacteria” The non-pathogenic strains are the ones to be used in this investigation. This is because they are safe to handle and are easy to grow under optimum conditions compared to other microbes.

     The population of bacteria increases by cytoplasmic division through the process of mitosis. Mitosis is the orderly increase in cellular components, segregation of DNA, followed by the division of the bacteria cell wall forming a daughter cell and a parent cell.

          [2]“Soon after  the antibiotics penicillin was discovered, it became clear that bacteria are capable of developing resistance due to mutation within the population through the process of natural selection”. Bacteria with allele that are more likely to survive the selection pressures reproduce. [3]“Over use of antibiotics increases the likely hood of selection of resistance strains over ones that are more susceptible to the antibiotics”

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      There are two types of antibiotics: bacteriacidal antibiotics which destroy bacteria and bacteriostatic antibiotics which has an indirect effect. A bacteriostatic antibiotic prevents the multiplication of pathogens. It then allows host immune system to destroy the pathogen.

          Antibiotics work in several ways to disrupt the growth of bacteria. These includes: Inhibiting of cell wall synthesis in bacteria, bacteria cell lyses caused by disruption of cell membrane and Inhibition of nucleic acid synthesis, replication and translation

Hypothesis

The antibiotic will inhibit the growth of bacteria, as the concentration of sodium chloride ...

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