Why NHS approved hand wash solution containing agents such as chlorhexidine Essay
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2. Explain why the alcohol-based solution, used during the hand washing procedure, should not be used in large quantities
Using hand wash in large quantities means that I can cause dryness and hardness in your hands. This can result in having cracked skin and also can lead to bleeding. Blood is warm and a liquid so this can allow and attract many pathogens such as bacteria and it can enter the body which is really bad for your skin. During experiments, you wear gloves so the alcohol-based solution will become moist and dry and in addition, bacteria like moist and warm places so they will be attracted to certain areas of your body.
Also, using small amounts of the hand wash is sufficient enough to sterilize your hands full. After using a large amount of hand wash, your hands will feel uncomfortable and also even more irritating when you have to wear gloves for experiments. Having bacteria in your blood flow means you could potentially become ill or even have an infection and that is not good.
When producing a serial dilution, explain why it is not satisfactory to only ‘approximately’ measure the sterile water?
It is not satisfactory to estimate measurements when doing the experiment, serial dilution. This can lead to inaccuracy in the results. There would be an effect on the volume of the cultures that would grow in the agar petri dish.
4. Why is it imperative to flame the lawn spreader when producing the spread plate?
It is crucial to flame the lawn spreader when producing the spread plate because high heat can kill the bacteria on the lawn spreader during the experiment. For example, serial dilution, you will need to use the lawn spreader at least 6 times for each petri dish which contains the agar. After using the lawn spreader once, it will then need to be dipped into the alcohol which is the ethanol and then the spreader should pass through the flame a couple of times to ignite the alcohol slightly. It should not be kept in the flame. Flaming is only essential for sterilizing the lawn spreader. Another effective way of sterilizing the lawn spreader is with ethanol which is used in the flame to burn off the alcohol. Another experiment which uses the flame is the streak plates. As the inoculating loop is dipped into the bacteria, it is then transferred onto the agar. Next, the inoculating loop is put into the flame and set to cool after. Then you should transfer the loop onto the agar again and do it two more times whilst flame the loop after each transfer. The results show that after flaming the loop, there are fewer bacteria and fewer colonies that have appeared for each transfer.
Explain why should Petri dishes be inverted prior to incubation?
Petri dishes should be inverted prior to incubation because it will prevent condensation falling onto the agar jelly which contains the microbes, so this will then contaminate the sample which means the result will be false. The condensation in the Petri dishes can cause bacteria to spread and could possibly mix. During experiments that make the petri dish warm such as the pour plate which you pour molten agar into the petri dish and seal once it has set. This means that the warmth inside the petri dish will attract more condensation than other experiments that we have done, for example, the serial dilution. We invert the Petri dishes so the water produced will drip onto the lid, and not on the agar jelly which contains the microorganisms that are growing. Inversion also avoids contamination in the petri dish which could possibly interfere with the growth of colonies of the microorganisms. Also, when inverted, the results are much easier to see.
Explain why it is necessary to flame the inoculating loop using a blue flame prior to streaking the plate at each parallel during streak plate isolation?
It is necessary to flame the inoculating loop using a blue flame to avoid contamination and because we use metal loops during experiments, the loops should be sterilized by placing the loop in the blue flame until the loop turns orange. It should be kept in the flame for a few seconds, making sure it has been thoroughly sterilized. You shouldn’t move the loop around in the air to cool it down because it won’t be as sterile as before and the loops can still be used when they are hot. You should always sterile the loop before and after using them to avoid contamination and decrease the number of bacteria which has been produced for the next set of streaks. Also, when flaming the loop, bacteria from the previous set of streaks will be killed. Another reason is that you want to have a really concentrated solution so that individual and isolated colonies can be formed on the agar jelly. This will then give you four sections of bacteria but after each one there are fewer bacteria/ fewer colonies formed.
Explain how streak plating can provide a way of separating bacteria in a mixed culture
Streak plating can provide a way of separating bacteria in mixed cultures because in your end results you want to have isolated colonies and if the bacteria that is formed on the agar jelly are spread out then this means it is much easier to identify by using the morphology. The morphology helps you to know what the shape, margin or even the pigmentation. Separating the bacteria in a mixed culture is a good idea because then the results will show you how each bacterium reacts to a mixed culture.