Investigate the Effect of Anti-Bacterial Products on the Growth on Skin Bacteria - Assignment Example

Microbes are organisms that get inside the human body, which then make you ill. There are two main types of microbes: bacteria and viruses. Bacteria are very small living cells; most are less than 1 micron (0.001mm) in length. They lack the internal call membranes, this means that they have no nucleus. Bacteria occur almost anywhere: in air, water, soil, and inside other organisms. They like warmth but some ca survive at the tops of the Alps where it is very cold. Others live in hot springs at near-boiling temperatures. Some bacteria are parasites and cause serious diseases. The microbes that cause disease are called pathogenic.

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If they enter the human body they damage cells and produces toxins which make you feel ill. Microbes can enter the human bodies in 5 different ways, through: the skin and eyes, the digestive system, the respiratory system, reproductive system and vector (mosquitoes, fleas).

Some bacteria are beneficial for example they are important in decomposition, getting rid of sewage and making butter yoghurt and cheese. In decomposition all plant matter and dead animals are broken down and decomposed. As a result of their activities simple substances are released from the dead bodies and plants can use these again.

Staphylococcus is a group of round parasitic bacteria, which is commonly found in air, water and on the skin. These bacteria are known to cause pneumonia, boils, kidney and wound infections. Two common species of Staphylococcus include Staphylococcus aureus, which is commonly responsible for skin infections, and Staphylococcus epidermis, which does not normally cause infection. However, either of these bacteria can cause serious infections under the right conditions.

In my experiment I am using Staphylococcus epidermis which does not usually cause infection. It is frequently present on most areas of the skin, in the nostrils, mouth, external ear, and urethra. Micrococcus luteus is a species of bacteria, which is also found on human skin.

The human skin is in contact with everything. The most outer layer called the epidermis is made of dead cells that are full of keratin and are very tough. They are waterproof and act as a barrier against bacteria and other micro-organisms. The dermis is the layer beneath the epidermis and is much thicker. Special blood cells migrate from the blood vessels and destroy invading organisms such as bacteria. Sebaceous glands produce an oily substance called sebum that coats the hairs and the skin. Sebum repels water and therefore helps to prevent the skin from drying out. It is also thought to help stop certain bacteria and fungi from growing this is called antiseptic. The more hair that is on the body then there will be more glands. Glands have no hair follicles in them.

If the dead cells on the surface of the skin dries out and cracks bacteria can enter easily. If the bacteria get into the pores they feed off the sebum. This then causes an infection, which produces a ‘spot’. The ‘spot’ becomes red because there is an excess amount of blood flowing to the infection. Then white blood cells come to the infected area and fight the infection.

Anti-bacterial products remove sebum so that your skin looks oil free and cleans the surface. This then makes the condition of the skin an unsuitable place for bacterial growth.

I hypothesise that the Clearasil Medicated Lotion will clear the agar plate the best in both bacteria. This is because the Clearasil is specifically designed to remove oil from the skin. This is because it contains a medical substance, which kills the well-known bacteria. The soapy solution will clear only some of the bacteria. This is because it is non-medicated and only contains 5% of soap in the solution. Although the soap is not specifically designed to remove bacteria like the Clearasil it still can clear some of the bacteria. This is because of the soap in the solution and the soap is still a clean agent. The water will have no effect because there is medicated agent and no cleaning agent in the water. So therefore I think that colonies of bacteria will grow near the water.

Equipment List

* One agar plate inoculated with Micrococcus luteus (ML) and one with Staphylococcus epidermis (SE)

* Clearasil medicated lotion

* 5% soapy solution (non-medicated)

* Water

* Bunsen burner

* Cork borer

* Fine spatula

* Sterilised pipettes

* Beaker of disinfectant

* Marker pen, sticky tape, goggles, a clean lab coat.


* Put on safety goggles. Take the cork borer and flame the end briefly in the Bunsen burner. Do not flame the end to long otherwise the heat will travel up to the top and burn you.

* Wait for it to cool. Then make 3 holes in the agar by pressing down with the cork borer in it. Remove the plugs with a fine spatula into a beaker of disinfectant. Do this as quickly as possible so that the bacteria can not escape.

* Turn the agar up side down and label the wells 1-3. Then add 0.5ml of each solution in to a well using sterilised pipettes and label: 1 = water, 2 = soap solution, 3 = Clearasil.

* Tape the lid to the base to make it physically secure. Keep the plate at 25 degrees Celsius. You must be very careful that when moving the plate to make sure that the solutions do not spill out of the wells.

* After the solutions have been saturated by the agar turn the plate up side down. This is to prevent condensation from changes the results.

* Record results every 2-3 days.


On day 1 of both the experiment the Clearasil, soap solution and water did not clear any zones. Throughout the whole experiment water did not clear any zones. So tis means that water dies not kill this bacteria from the skin. However on day 3 there were colonies of bacteria growing on the SE. This proves that water does not pervent this type of bacteria.

All of the solutions worked better on ML than SE. This is including water because although there were no clear zones around the water at least on ML there were no visible bacteria growing anywhere. Out of all the products Clearasil worked the most effective in killing the bacteria because it cleared the most in the agar plates. On ML for Clearasil nothing happened on day 1 and on day 3 it cleared in diameter 3.5 cm. This 3.5 cm is also including the size of the well, which is 1 cm in diameter so therefore Clearasil only cleared 2.5 cm. On day 6 it showed that the agent was still working because the diameter rose to 3.9 cm that meant it cleared 2.9 cm.

So from day 3-6 there was only a little change this might be because the entire agent in the Clearasil was used up. From day 1-3 there was a great increase in diameter this showed that the agent worked quickly probably in day 2. Clearasil worked the best because it had a medicated agent added to it that was specifically designed to kill bacteria. However Clearasil worked better on ML than SE so therefore I think that Clearasil must have a specific agent in it to kill Ml bacteria and not a specific agent to kill SE bacteria. On SE again Clearasil worked the best because it cleared the most in diameter.

Again nothing happened for all the agents on day 1 and on day 3 Clearasil had cleared 1.4 cm in diameter including the diameter of the well. So this means it only cleared 0.4 cm in diameter because the well was 1 cm. On day 6 it then only cleared a little more and 1.6 cm. On SE for soap solution it did not clear any zones so therefore it did not kill any bacteria. However there was no colonies of bacteria growing around it so therefore it prevented visible bacteria growing.

On SE for water again nothing happened from 1-3 days. On day 6 the there were colonies on bacteria growing inside the well and outside the well. On ML the soap solution worked second effective after Clearasil. From day 1-3 it cleared 1.5 cm meaning it only cleared 0.5 cm in diameter. From day 3-6 it cleared an extra 0.1 cm in diameter, although this was not much of a change it still shows that the solution was working. The bacteria were left in a 25 degrees Celsius environment.

Therefore overall Clearasil worked the most effective on both the bacteria. However it worked better on ML than SE.


The equipment and procedure I used to obtain my evidence was very accurate. After we used equipment that had touched the bacteria we put it in a beaker of disinfectant so that there was no chance of bacterial growth. The accuracy of the experiment was very good because after day 3 or so we turned the plates upside down so that the condensation would effect our results. If we were to have left it upright then the condensation would have mixed with he solutions and made them dilute. Then this would make it an unfair test. There were not any anomalous results. However I expected soap solution to have worked better on SE than I had predicted. The ways in which I could have improved my procedure it that I could have taken more results.

For example in I had taken results on day 2 for Clearasil on ML then I could have seen weather the solution worked better on day 2 or day 3. Therefore I should have taken daily results to enforce the results, then I could have seen a gradual increase. From the evidence I have obtained from conclusion I would definitely say that Clearasil worked as the most effective. I could have don further worked by put my agar plate at room temperature and seeing if the warmth makes any differences. If I had put it outside I think it might have been better because then the temperature changes just like your skin if it is hot or cold.