Cafeteria Dining: Location Determines Cleanliness 

Abstract

The idea of the following experiment was to find out whether the chairs and tables in one cafeteria, classified as Lower Caf, were more concentrated with bacteria than the chairs and tables in the other cafeteria upstairs, classified as Upper Caf. The hypothesis was that the chairs and tables in Upper Caf would have more bacteria because it was more populated and took up a larger space that couldn’t be cleaned as effectively. To test whether the hypothesis was supported or not, the chairs and tables from Lower Caf and Upper Caf were carefully swabbed and the bacteria was left to grow on agar in sterile petri dishes. After about 72 hours of constant bacteria growth, the students compared the differences from the two

Abstract

The idea of the following experiment was to find out whether the chairs and tables in one cafeteria, classified as Lower Caf, were more concentrated with bacteria than the chairs and tables in the other cafeteria upstairs, classified as Upper Caf. The hypothesis was that the chairs and tables in Upper Caf would have more bacteria because it was more populated and took up a larger space that couldn’t be cleaned as effectively. To test whether the hypothesis was supported or not, the chairs and tables from Lower Caf and Upper Caf were carefully swabbed and the bacteria was left to grow on agar in sterile petri dishes. After about 72 hours of constant bacteria growth, the students compared the differences from the two cafeterias. Despite practical speculation, the evidence that was gathered did not support the hypothesis in the end because Lower Caf had more bacteria than Upper Caf; the students forgot two potential reasons that may have contradicted the assumption. The first, was that because Upper Caf was more populated it was cleaned more often, and the second was that Upper Caf provided hand sanitizer and other cleaning devices which helped the overall environment. After the experiment was finished, the students concluded that places that had a higher usage for food consumption (e.g., a kitchen over a bedroom) were ideal for eating at because they were cleaned more often and had more available cleaning options (e.g. a kitchen has a sink and provides soap).

Introduction

Many assume that modern technology has fixed the issue of bacteria-ridden food, but often overlook the process. Something as simple as washing your hands may look easy, but a majority of people fail to complete it properly. According to a study called Practice of hand hygiene in a university dining facility, conducted on food handlers, the average time (seconds) that a person spent working on hand hygiene before and after preparing meals was 12.89 ± 7.25 s (do Prado et al., 2015). In other words, the food handlers were not committed to properly going through the steps of washing their hands. This begs the question, how clean is a school cafeteria?

In order to find out, a group of students tested the amount of bacteria on the chairs and tables of both the cafeterias at their school. In a recent study done in 2018 called Assessment of food safety at university food courts using surveys, observations, and microbial testing, generic E. coli was found on about 11.9% of salad bar/utensils and 9.8% of food serving counters (Her et al., 2018). The finding of generic E. coli is generally a clear indication of fecal contamination, which provides for a series of harmful organisms, whether they be bacterial, viral, or parasitical. Although this did not directly correlate with the objects being tested in the students’ experiment, it indicated that public utilities are highly stricken with bacteria, which includes chairs and tables.

The students had access to two different cafeterias, Lower Caf and Upper Caf, allowing them to test how student usage/popularity corresponded with the total amount of bacteria found in either location. Their hypothesis was that when tested, Upper Caf chairs and tables would have more bacteria than the chairs and tables found in Lower Caf. The independent variable used was the location of the chairs and tables that were tested. The dependent variable was the total amount of bacteria found from the chairs and tables (through petri dishes). Several control groups were used during the experiment, which involved the usage of a sterile cotton-tipped applicator, the total amount of time the petri dishes were left in an incubator, temperature, and the specific agar used in order to feed the bacteria. They predicted that the chairs and tables that resided in Lower Caf would have less bacteria than the chairs and tables in Upper Caf because fewer people ate lunch in Lower Caf and therefore not as much bacteria would be spread.

Materials & Methods

Materials:

Five sterilized petri dishes with agar, five cotton-tipped applicators, two chairs (one from Lower Caf and the other from Upper Caf), two tables (one from Lower Caf and the other from Upper Caf), a black fine point sharpie (used in order to label petri dishes), and an incubator set at a constant temperature of 37°C.

Method:

Using a sterile cotton-tipped applicator, swab the entire surface of a chair in Lower Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Using a different sterile cotton-tipped applicator, swab the entire surface of a table in Lower Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Using a different sterile cotton-tipped applicator, swab the entire surface of a chair in Upper Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Using a different sterile cotton-tipped applicator, swab the entire surface of a table in Upper Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Take a sterile cotton-tipped applicator and gently swab it on the agar of the petri dish. This step must be done as quickly as possible so that no bacteria from the air contaminates the applicator. Quickly seal and label the petri dish. This will be used as the control. Take all five petri dishes and tape them together. Place all five petri dishes in an incubator at 37°C for 72 hours. Take petri dishes out of the incubator and observe, taking note of the amount and size of colonies for each experimental group.

Results

This petri dish contained bacteria from a randomly selected chair in Lower Caf. There were 2 bacteria colonies in the bottom left quadrant and 1 bacteria colony in the top left quadrant, resulting in a total of 3 colonies. Although the speckled dots in the middle of the petri dish look like bacteria colonies, they are only condensation droplets that were produced during the incubator part of the experiment.

This petri dish contained bacteria from a randomly selected table in Lower Caf. This petri dish had the highest number of colonies form. There were 13 bacteria colonies on the left half and 7 on the right, resulting in a total of 20 colonies. All but one of the colonies were moderately sized. A relatively large colony formed on the agar in the bottom left quadrant, giving the appeal of a big bubble. This petri dish contained bacteria from a randomly selected chair in Upper Caf. There were 2 bacteria colonies on the left half and none on the right half. Both bacteria colonies were relatively small compared to the other colonies found in other petri dishes.

This petri dish contained bacteria from a randomly selected table in Upper Caf. There were 5 bacteria colonies on the left half and 1 bacteria colony on the right half, resulting in a total of 6 colonies. All of the colonies were moderately sized and none were noticeably larger than the rest. This petri dish was the control group. One cotton-tipped applicator was used to swab the air and then be applied to the agar. This petri dish had the smallest amount of bacteria colonies with zero.

The graph shows how many bacteria colonies formed in each petri dish. It does not show how much bacteria there was in total or the size, but only the number of colonies formed. The sample from a randomly selected table in Lower Caf had the most bacteria colonies, with no other sample coming remotely close. The sample with the least amount of colonies (besides control) was of a randomly selected chair in Upper Caf.

Discussion

After the experiment was over, the students concluded that the evidence did not support their hypothesis. This is because the amount of bacteria colonies found on the chairs and tables in Lower Caf (Figures 1 & 2) were significantly greater than the amount of bacteria colonies found on the chairs and tables in Upper Caf (Figures 3 & 4). The randomly selected Lower Caf table had a staggering 14 more bacteria colonies over the table selected in Upper Caf. Despite the fact that the chair in Lower Caf had only one more bacteria colony than the chair in Upper Caf, it still is a higher number and makes a difference in the end. Also, regardless of the cafeteria, the tables had higher amounts of bacteria over the chairs, which shows that the object in itself also matters and the location does not necessarily define it. However, one problem stood out to the students. Why was the difference of bacteria between the two different chairs so minimal, yet the difference of bacteria between the two different tables so significant? The students suspected that an unaccounted factor or human error might have occurred, such as the table they selected in Lower Caf just happening to have a large amount of bacteria that day or being possibly tainted from another source (e.g. human contamination or another object). This led the students to think of other human errors or unaccounted factors that might have appeared during their experiment.

For example, the most likely source of error was the exposure to air that the sterile applicators underwent when swabbing the chairs and tables. The experiment was not performed in a sterile environment, allowing bacteria to contaminate the samples and therefore exaggerate the data/results. To add on, there might have been instances in which the students had come in close contact with the sterile applicators; the experiment had to be carefully conducted and the process took a long time. However, no official contact had been witnessed between the students, but they could have been looking away during the moment or not paying attention. Furthermore, another possible source of error could have been the fact that the control was switched between the other samples. When the students were done conducting the experiment, they noticed that the petri dish labeled as the “control”, actually had bacteria in it. They questioned how the control could have possibly received the bacteria in the first place until a student in their group remembered that she accidentally switched two petri dishes during the labeling phase of the experiment. Although the student had claimed/thought she switched them, she might not have, and the control might actually be tainted. This would invalidate the experiment because the independent and dependent variables would be altered. Despite the fact that these possible errors could have modified the results, the hypothesis still was not supported by the evidence.

A potential reason why the hypothesis was not supported is that Upper Caf gets cleaned more often because it is usually more populated than Lower Caf. Not only that, but Lower Caf is usually just a social location over a typical eating area, as it provides ping pong tables for student usage and is generally seen as just somewhere to meet up with friends. This means that janitors will primarily prioritize cleaning Upper Caf, as it is much larger and is primarily an eating place. Another potential reason is that Upper Caf provides hand sanitizer and other cleaning devices. This will ensure that the overall environment is hygienic, and reduces the amount of bacteria spread among the cafeteria. Although the hypothesis was not supported, it is still important to list the reasons why, in order to come up with a more accurate prediction next time.

In the end, the students learned to take precautionary measures when eating in either cafeteria. They recommend to wash hands with hand sanitizer before eating and to never eat any food that is dropped on a table. Although the chairs also had bacteria on them, they only had a small amount, leaving them fairly harmless compared to the tables. The students also learned that eating in a place designated for actual eating lowers the risk of food-borne illnesses because there are fewer bacteria. For example, the students recommend to eat in the kitchen over a bedroom because the kitchen is more likely to be cleaned for eating purposes. In the future, the testing of other cafeteria conditions should be tested (e.g. common utensils or the food), in order to spread awareness about how dirty they might actually be. In order to follow up with the results, the sterilization of the chairs and tables should be done at the same time period to ensure that the bacteria change of each sample remains consistent with how much time they had been out. In conclusion, it is important to take precautions when eating in a public setting, and the location also plays a big role in the amount of bacteria an environment has.

cafeterias. Despite practical speculation, the evidence that was gathered did not support the hypothesis in the end because Lower Caf had more bacteria than Upper Caf; the students forgot two potential reasons that may have contradicted the assumption. The first, was that because Upper Caf was more populated it was cleaned more often, and the second was that Upper Caf provided hand sanitizer and other cleaning devices which helped the overall environment. After the experiment was finished, the students concluded that places that had a higher usage for food consumption (e.g., a kitchen over a bedroom) were ideal for eating at because they were cleaned more often and had more available cleaning options (e.g. a kitchen has a sink and provides soap).

Introduction

Many assume that modern technology has fixed the issue of bacteria-ridden food, but often overlook the process. Something as simple as washing your hands may look easy, but a majority of people fail to complete it properly. According to a study called Practice of hand hygiene in a university dining facility, conducted on food handlers, the average time (seconds) that a person spent working on hand hygiene before and after preparing meals was 12.89 ± 7.25 s (do Prado et al., 2015). In other words, the food handlers were not committed to properly going through the steps of washing their hands. This begs the question, how clean is a school cafeteria?

In order to find out, a group of students tested the amount of bacteria on the chairs and tables of both the cafeterias at their school. In a recent study done in 2018 called Assessment of food safety at university food courts using surveys, observations, and microbial testing, generic E. coli was found on about 11.9% of salad bar/utensils and 9.8% of food serving counters (Her et al., 2018). The finding of generic E. coli is generally a clear indication of fecal contamination, which provides for a series of harmful organisms, whether they be bacterial, viral, or parasitical. Although this did not directly correlate with the objects being tested in the students’ experiment, it indicated that public utilities are highly stricken with bacteria, which includes chairs and tables.

The students had access to two different cafeterias, Lower Caf and Upper Caf, allowing them to test how student usage/popularity corresponded with the total amount of bacteria found in either location. Their hypothesis was that when tested, Upper Caf chairs and tables would have more bacteria than the chairs and tables found in Lower Caf. The independent variable used was the location of the chairs and tables that were tested. The dependent variable was the total amount of bacteria found from the chairs and tables (through petri dishes). Several control groups were used during the experiment, which involved the usage of a sterile cotton-tipped applicator, the total amount of time the petri dishes were left in an incubator, temperature, and the specific agar used in order to feed the bacteria. They predicted that the chairs and tables that resided in Lower Caf would have less bacteria than the chairs and tables in Upper Caf because fewer people ate lunch in Lower Caf and therefore not as much bacteria would be spread.

Materials & Methods

Materials:

Five sterilized petri dishes with agar, five cotton-tipped applicators, two chairs (one from Lower Caf and the other from Upper Caf), two tables (one from Lower Caf and the other from Upper Caf), a black fine point sharpie (used in order to label petri dishes), and an incubator set at a constant temperature of 37°C.

Method:

Using a sterile cotton-tipped applicator, swab the entire surface of a chair in Lower Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Using a different sterile cotton-tipped applicator, swab the entire surface of a table in Lower Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Using a different sterile cotton-tipped applicator, swab the entire surface of a chair in Upper Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Using a different sterile cotton-tipped applicator, swab the entire surface of a table in Upper Caf. Then quickly take the applicator and gently swab it on the agar of the petri dish. Quickly seal and label the petri dish. Take a sterile cotton-tipped applicator and gently swab it on the agar of the petri dish. This step must be done as quickly as possible so that no bacteria from the air contaminates the applicator. Quickly seal and label the petri dish. This will be used as the control. Take all five petri dishes and tape them together. Place all five petri dishes in an incubator at 37°C for 72 hours. Take petri dishes out of the incubator and observe, taking note of the amount and size of colonies for each experimental group.

Results

This petri dish contained bacteria from a randomly selected chair in Lower Caf. There were 2 bacteria colonies in the bottom left quadrant and 1 bacteria colony in the top left quadrant, resulting in a total of 3 colonies. Although the speckled dots in the middle of the petri dish look like bacteria colonies, they are only condensation droplets that were produced during the incubator part of the experiment.

This petri dish contained bacteria from a randomly selected table in Lower Caf. This petri dish had the highest number of colonies form. There were 13 bacteria colonies on the left half and 7 on the right, resulting in a total of 20 colonies. All but one of the colonies were moderately sized. A relatively large colony formed on the agar in the bottom left quadrant, giving the appeal of a big bubble. This petri dish contained bacteria from a randomly selected chair in Upper Caf. There were 2 bacteria colonies on the left half and none on the right half. Both bacteria colonies were relatively small compared to the other colonies found in other petri dishes.

This petri dish contained bacteria from a randomly selected table in Upper Caf. There were 5 bacteria colonies on the left half and 1 bacteria colony on the right half, resulting in a total of 6 colonies. All of the colonies were moderately sized and none were noticeably larger than the rest. This petri dish was the control group. One cotton-tipped applicator was used to swab the air and then be applied to the agar. This petri dish had the smallest amount of bacteria colonies with zero.

The graph shows how many bacteria colonies formed in each petri dish. It does not show how much bacteria there was in total or the size, but only the number of colonies formed. The sample from a randomly selected table in Lower Caf had the most bacteria colonies, with no other sample coming remotely close. The sample with the least amount of colonies (besides control) was of a randomly selected chair in Upper Caf.

Discussion

After the experiment was over, the students concluded that the evidence did not support their hypothesis. This is because the amount of bacteria colonies found on the chairs and tables in Lower Caf (Figures 1 & 2) were significantly greater than the amount of bacteria colonies found on the chairs and tables in Upper Caf (Figures 3 & 4). The randomly selected Lower Caf table had a staggering 14 more bacteria colonies over the table selected in Upper Caf. Despite the fact that the chair in Lower Caf had only one more bacteria colony than the chair in Upper Caf, it still is a higher number and makes a difference in the end. Also, regardless of the cafeteria, the tables had higher amounts of bacteria over the chairs, which shows that the object in itself also matters and the location does not necessarily define it. However, one problem stood out to the students. Why was the difference of bacteria between the two different chairs so minimal, yet the difference of bacteria between the two different tables so significant? The students suspected that an unaccounted factor or human error might have occurred, such as the table they selected in Lower Caf just happening to have a large amount of bacteria that day or being possibly tainted from another source (e.g. human contamination or another object). This led the students to think of other human errors or unaccounted factors that might have appeared during their experiment.

For example, the most likely source of error was the exposure to air that the sterile applicators underwent when swabbing the chairs and tables. The experiment was not performed in a sterile environment, allowing bacteria to contaminate the samples and therefore exaggerate the data/results. To add on, there might have been instances in which the students had come in close contact with the sterile applicators; the experiment had to be carefully conducted and the process took a long time. However, no official contact had been witnessed between the students, but they could have been looking away during the moment or not paying attention. Furthermore, another possible source of error could have been the fact that the control was switched between the other samples. When the students were done conducting the experiment, they noticed that the petri dish labeled as the “control”, actually had bacteria in it. They questioned how the control could have possibly received the bacteria in the first place until a student in their group remembered that she accidentally switched two petri dishes during the labeling phase of the experiment. Although the student had claimed/thought she switched them, she might not have, and the control might actually be tainted. This would invalidate the experiment because the independent and dependent variables would be altered. Despite the fact that these possible errors could have modified the results, the hypothesis still was not supported by the evidence.

A potential reason why the hypothesis was not supported is that Upper Caf gets cleaned more often because it is usually more populated than Lower Caf. Not only that, but Lower Caf is usually just a social location over a typical eating area, as it provides ping pong tables for student usage and is generally seen as just somewhere to meet up with friends. This means that janitors will primarily prioritize cleaning Upper Caf, as it is much larger and is primarily an eating place. Another potential reason is that Upper Caf provides hand sanitizer and other cleaning devices. This will ensure that the overall environment is hygienic, and reduces the amount of bacteria spread among the cafeteria. Although the hypothesis was not supported, it is still important to list the reasons why, in order to come up with a more accurate prediction next time.

In the end, the students learned to take precautionary measures when eating in either cafeteria. They recommend to wash hands with hand sanitizer before eating and to never eat any food that is dropped on a table. Although the chairs also had bacteria on them, they only had a small amount, leaving them fairly harmless compared to the tables. The students also learned that eating in a place designated for actual eating lowers the risk of food-borne illnesses because there are fewer bacteria. For example, the students recommend to eat in the kitchen over a bedroom because the kitchen is more likely to be cleaned for eating purposes. In the future, the testing of other cafeteria conditions should be tested (e.g. common utensils or the food), in order to spread awareness about how dirty they might actually be. In order to follow up with the results, the sterilization of the chairs and tables should be done at the same time period to ensure that the bacteria change of each sample remains consistent with how much time they had been out. In conclusion, it is important to take precautions when eating in a public setting, and the location also plays a big role in the amount of bacteria an environment has.