Investigating the Effect of Antimicrobials on Different Microbes Paper Example

Paper Type:  Report
Pages:  7
Wordcount:  1815 Words
Date:  2022-05-26

Topic: Investigating the effect of antimicrobials on different microbesAim: To design, carry out and analyse the effect of antimicrobials on different microbes.

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Introduction

Antimicrobials are agents that kills microorganisms or stops their growth which includes; disinfectants, antiseptics and antibiotics. Antimicrobial agents have various functions which they perform through various mechanisms of actions that include inhibition of protein synthesis, interference with cell wall and nucleic acid synthesis, breakdown and disruption of bacteria membrane structure and inhibition off metabolic pathways. Bacteria may be either resistant to microbial agent intrinsically or acquire resistance by mutation through acquisition of resistance genes from other organisms (Demiraslan, H. and Uysal, E. 2018, 15). The acquire resistance genes may enable a bacteria to express resistance by producing enzymes that destroy the antibacterial agents. This prevents the drug from acting on the bacteria by preventing it from reaching its intracellular target site or modify other metabolic pathways that used be used to facilitate the action of the drug (Demiraslan, H. and Uysal, E. 2018, 25).

New genetic material acquired from resistant strains of bacteria transform the antimicrobial susceptible bacteria to resistant strains. This occurs through conjugation, transformation or transduction. Transposons allow incorporation of resistant genes into the host's genome making it resistant. With the emergence of resistance strains, the use of antibacterial agents may not work effectively as it creates selective pressure.

Disinfection is a procedure that destroys or inactivates microbes. It usually involves the treatment on non-living objects such as surfaces or liquids with chemicals (disinfectants) e.g. chlorine, phenols and hypochlorite. Antisepsis is the disinfection of living tissues with chemicals (antiseptics) e.g. hydrogen peroxide, iodine and diluted alcohol. Antibiotics are chemicals that even at very low concentrations inhibit or kill certain microbes. Penicillin are a well-known group of antibiotics (Gajdacs, M., Spengler, G. and Urban, E. 2017, 25).

Disinfectants and antiseptics that kill bacteria are said to be bactericidal. Others merely halt the growth of bacteria and if inactivated e.g. by dilution, bacterial growth may be resumed. These are said to be bacteriostatic. A bactericidal disinfectant or antiseptic may become bacteriostatic when diluted (Demiraslan, H. and Uysal, E. 2018, 2).

Microbes produce antibiotics as a natural defence against other microbes. Some are still produced commercially, although a large number are manufactured chemically. Some antibiotics are active against a narrow range of species whilst others affect a broad spectrum of organisms. The ability to make antimicrobial substances is not limited to microbes; most animals have antibacterial substances in their body secretions, such as lysozyme in sweat and tears. Plant materials such as garlic, tea tree oil and oil of cloves also have antimicrobial properties.

Apparatus and Materials

Apparatus: Agar plate, Bunsen burner, marker pen, autoclaved forceps.

Materials: Bacteria E. coli, bacteria S. aureus, bench spray of disinfectant, 1% Virkon, soap and dettol, paper towels, antibiotic- impregnated paper disc, adhesive tape.

Safety

Micro-organisms are widely distributed in nature. They are found in the air, in soil and water, on the skin and in the alimentary and upper respiratory tracts of all animals. The majorities are generally harmless, but some are "naturally" harmful and will give rise to infections in the body.

The behaviour of even normally harmless micro-organisms cannot be predicted should they be given the opportunity to develop in a new environment. It is therefore a general rule that all cultures that you handle are to be considered as potentially harmful (Demiraslan, H. and Uysal, E. 2018, 21).

Working safely is very important in microbiology. There are lots of hazards.

These include:

  • The microbes that you are using making you ill
  • Getting burnt from the Bunsen burner or the alcohol used to sterilize equipment
  • Avoid staining your skin with some of the chemicals that you will use.

Protecting Yourself:

  • Before starting work, wash your hands and cover any open cuts with a waterproof dressing.
  • You must wear a laboratory coat, safety glasses and plastic apron whilst in the laboratory
  • If you have long hair make sure that it is tied back.
  • You must not eat or drink whilst in the laboratory. This includes chewing gum. Other forms of hand-to-mouth contact must be avoided.
  • Assign one part of your bench for writing materials etc. as a "clean" area, and the area near your Bunsen as a "dirty" area.

Protecting Others

Your working area must be cleaned with a small amount of alcohol on the tissue before starting work and after your laboratory session.

Bunsen burners are potential hazards, especially when used at the same time as the alcohol. Turn them to a luminous flame when not in use and always replace the lid on the alcohol containers immediately after use (Muthuirulan, P. 2016, 7).

Before leaving your benches put away all equipment and turn off all gas and electrical supplies.

Finally, after removing your lab coat and before leaving the laboratory to wash your hands thoroughly in one of the hand washing sinks provided.

Precautions:

1. Before setting the agar, pipet the bacteria first to allow the agar to mix well with the bacteria.

2. Avoid lifting up Petri dishes lid during the observation as bacteria are harmful to our health.

3. Wash your hands thoroughly with disinfectant after working with the bacteria culture to avoid any infections.

Procedure:

Wash your hands thoroughly with Dettol hand wash. Disinfect the working area by spraying a disinfectant to avoid contamination. Use paper towels to wipe the working area.

Two sterile Petri dishes that are correctly labelled. One of the Petri dishes is filled with the bacteria S. aureus and another one with E. coli. The label is pasted at the side of the Petri dishes.

The apparatus needed: bottle containing sterile nutrient agar, micropipette with sterile tips, Bunsen burner, bottle containing bacteria cultures and sterile Petri dishes labelled correctly (Muthuirulan, P. 2016, 4).

200ml of E. coli bacteria culture is pipetted into a sterile Petri dish beside a burning Bunsen burner.

Pour molten agar into the petri dish until the bottom of the petri dish is covered by the agar.

The Petri dish is well covered with a lid and gently shaken in all directions to ensure that the bacterium in the dish mixes well with the agar.

The agar is then allowed to set.

Steps 4 to7 are repeated for S. aureus.

Allow the 2 Petri dishes containing agar to set.

By using a pair of forceps Place one paper disc in an antibiotic solution named Ampicillin.

The paper disc is then soaked into Petri dish containing the agar.

Steps 10- 11 are repeated for antibiotics Tetracycline, Carbenicillin, and sterilized distilled water.

The Petri dish is closed and the bottom of the Petri dish is labelled to identify the position of each paper disc.

The agar plates are then left in 30.0 0C incubator for 24 hours.

After working with the bacteria culture, make sure you wash your hands thoroughly again.

After 24 hours, observe the agar plates when the Petri dishes are still closed. Measure the diameter of the clear region around the paper disc and record them on a table (Muthuirulan, P. 2016, 4).Result:

Antibiotics Diameter of the clear zone, cm (E. coli) Diameter of the clear zone, cm (S. aureus)

Ampicillin 3.2 3.0

Tetracycline 2.3 2.7

Carbenicillin 1.3 2.8

Distilled Water 0.5 0.5

R>/= 1 susceptibility

R<1 resistance

Discussions:

Analysis of Data

From the results obtained from the experiment, it is found that the largest inhibition zone or clear region is formed around the paper disc soaked in Ampicillin for E. coli bacteria having a diameter of 3.2cm followed by Tetracyclin with a diameter of 2.3cm and Carbenicillin with a diameter of 1.3cm respectively. Since Ampicillin's paper disc caused the largest area of inhibition zone in E. coli, this showed that Ampicillin is most effective antibiotic compared to Tetracyclin and Carbenicillin in inhibiting the growth of the E. coli. On the other hand, Carbenicillin's paper disc caused the smallest area of inhibition zone in E. coli which was an indication that it is the weakest antibiotic against E. coli.

Also, Ampicillin was found to be the most effective antibiotic against bacteria Staphylococcus aureus due to the large area of inhibition zone around the paper disc soaked with Ampicillin solution was the greatest with a diameter of 3.0cm. Followed by a Carbenicillin with a diameter of 2.8cm and the least effective antibiotic is Tetracyclin with a diameter of 2.7 cm respectively.

From the above data, we can thus conclude that Ampicillin is the most effective antibiotic against both E. coli and S. aureus and was the broad spectrum antibiotic. Tetracyclin and Carbenicillin have a varying effective towards both bacteria indicating that antibiotics have specific effects on different bacteria (Demiraslan, H. and Uysal, E. 2018, 23).

The inhibitions or clear zones indicate susceptibility of the bacteria to the antibacterial agents. If no inhibition or clear zone recorded, it indicates that the bacteria exhibit resistance. The diameter is measured by using two points in the inhibition or clear region furthest from each other in cases where the zones are not circular. The difference in the diameter of the various inhibition zones is directly proportional to the strength of the antimicrobial properties of the antibiotics towards the various bacteria. When prescribing antibiotics, those with large inhibition zones are more effective in treating bacterial infection. However, other factors should be considered when administering the drugs which include patients' conditions and the side effects brought about by the drug (Gajdacs, M., Spengler, G. and Urban, E. 2017, 24).

Control

Sterilized distilled water in this experiment is used as the control. The paper discs having been soaked in the sterilized distilled water have also to be put into the two Petri dishes. The aim of doing this is to show that distilled water has no effects on bacteria. As a result, we are in a position to compare the different results of the paper discs and antibiotics and the distilled water and to show that the formation of the inhibition zone is caused by the effects of antibiotics and not water. The clear region does not appear around the paper disc that was soaked in distilled water in both the Petri dishes (Gajdacs, M., Spengler, G. and Urban, E. 2017, 25). Thus, we are in a firm position to conclude that when the clear region forms around the paper discs, it can only be due the microbial property of the antibiotics and not that of distilled water.

Variables

In this experiment, three different antibiotics have been used to help manipulate the different types of antibiotics and compare their effectiveness in inhibiting the growth of bacteria. The three antibiotics used are Ampicillin, Tetracycline, and Carbenicillin. There are two different types of bacteria used, i.e., S. aureus and E. coli that are placed in two different Petri dishes with agar medium to help in the results manipulation (Demiraslan, H. and Uysal, E. 2018, 29). The different bacteria help us to identify the various antimicrobial properties of the same antibiotics when place in different bacteria types.

The variable recorded in this experiment is the diameter of the clear region around the paper discs after 24hrs. The diameter of t...

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Investigating the Effect of Antimicrobials on Different Microbes Paper Example. (2022, May 26). Retrieved from https://proessays.net/essays/investigating-the-effect-of-antimicrobials-on-different-microbes-paper-example

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