Antibiotic lab report


Only 1% of bacteria are harmful for humans however there are strategies of preventing the spread of the dangerous micro organism. Chemical substances which are used to both kill or inhibit development of bacteria are generally known as antimicrobial brokers, of which the three basic types are disinfectants, antiseptics and antibiotics. Disinfectants are chemical compounds used to inhibit progress or kill micro organism on residing tissues, antiseptics inhibit progress or kill bacteria on nonliving issues and antibiotics are compounds that block the growth and replica of micro organism.

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Although microorganisms can develop a resistance to those agents, the effectiveness is decided by factors similar to environmental circumstances and so on.


Since the effectiveness varies, if environmental components and different circumstances were saved the same, the antibiotic could be best.


1 antibiotic disk (Erythromycin)
Distilled water
Culture of e-coli (Escherichia coli)
1 sterile filter-paper disk
Transparent tape
1 sterile nutrient agar plate
Metric ruler
1 sterile inoculating loop.


Part A: Set up of Nutrient Agar plate
1. Get an agar plate and carefully flip it over (being careful to not open the dish)
2. Draw two lines (forming right angles) to separate the dish into quarters. Number the quadrants 1-4 on the sides solely (see figure 1). Turn the dish back up. DO NOT SPILL.
three. Insert inoculating loop by lifting top lid slightly (at an angle).
4. Swipe the loop over the bacteria culture. DO NOT DIG INTO CULTURE.
5. Slightly open nutrient agar plate and place tip of inoculating loop on the top heart of agar and steak the agar (see determine 2). Turn dish 90o and repeat.

Immediately dispose loop

Part B: Placement of Antimicrobials
1. Select three antimicrobials
2. Slightly open inoculated agar plate. Place a disk in the center of one of the quadrants using forceps gently till it sticks and then shut petri dish.
three. Repeat step two with the disks of the opposite two antimicrobials. Place an empty disk within the remaining quadrant (control).
four. Tape the petri dish to safe tightly.

Part C: Results
1. Observe the dish after 48 hours
2. Measure the world away from bacteria (the clear space is the zone of inhabitance) using a metric ruler.
three. Record results and return the dish to trainer for correct disposal. It is necessary to not open the sterile agar plates so that the micro organism don’t spill and keep away from contamination. Its necessary to solely write on the perimeters of the plate so that it’s straightforward to see the areas needed for observation It is necessary to make use of sterile methods while inoculating the agar plates in order that micro organism don’t get on something nor are added in the experiment. Control disks are used to be able to have a basis for comparability. It is important to tape the dish to find a way to avoid spills and contamination of objects by the bacteria.

Analysis: we used a control disk so as to base the results on one thing in order to compare the effectiveness of the antimicrobials. Without the management, we’d haven’t any basis for comparison. The antibiotics did not do as good of a job as expected as a result of they need to be continuously taken for a set period of time. Due to this cause, doctors subscribe antibiotics for 10 days and if use is stopped earlier than that period, they can easily divide and multiply. The college toilet soap showed the best results because it had the most amount of clear space. The use of a control confirmed that the inhabitance of bacteria noticed was due to the antibiotic on the disk somewhat than the disk itself. If a critical staphylococcus an infection developed within the locker room of the college gym and I were in cost, I would take a sample of the bacteria and repeat this experiment to have the ability to discover the best disinfectant.

I suppose that antibiotics appear to lose their effectiveness against a particular inhabitants of bacteria after a protracted period of time as a outcome of they adapt to the change and mutate overtime. It is essential to take an antibiotic for the exact period of time it’s prescribed as a outcome of the bacteria could presumably be dormant and if not utterly killed, they can simply reproduce and make the person unwell once more. If I have been infected with E-coli I would need to be prescribed a stronger antibiotic than erythromycin as a result of it didn’t give one of the best result within the experiment.

Discussion: All antimicrobials used inhibited the growth of the bacteria to some extent however the college toilet soap showed one of the best results and inhibited development to the furthest extent, which rejected my speculation. Although it did inhibit growth higher than others, it wasn’t as efficient as the school bathroom cleaning soap. I thought the antibiotic would work finest, as it’s the most common used antimicrobial in hospitals nonetheless as a result of it was solely used as quickly as, it was fairly ineffective. The hand sanitizer was least efficient as it barely inhibited development. In the top the hand sanitizer and antibiotic disks were both semi cloudy whereas the lavatory cleaning soap was clear. In conclusion the lavatory cleaning soap labored a lot better than I expected and I would absolutely use it earlier than and after lunch in order to avoid being infected.

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