The Effects of Classroom Cleaning Protocols on Parasitic Bacterial Growth


Bacteria can be found on nearly all surfaces that come into contact with humans. Although many bacteria are harmless, those deemed pathogenic are capable of causing human disease. When humans share an environment, such as a school, many surfaces become a source for transmissible bacteria. With large numbers of people confined in a single building, different types of bacteria from different people can be transmitted to surfaces. Once on a surface, another person may come into contact with a parasitic bacterium and become infected, specially at home you need to be very careful with the bacteria, cleaning services dublin can help you doing a deep cleaning to prevent the spread.
Some common illnesses are caused by bacteria which could have been prevented with the proper use of cleaning agents. Without knowing which surfaces have the highest concentrations of bacteria, cleaning implementations cannot be properly established. The purpose of this study is to learn the specific locations of abundant bacteria so adjustments can be made to cleaning procedures. With less pathogenic bacteria on surfaces, it is likely to improve the health of students and staff. Further, the rationale of this research is exploratory and not based on a hypothesis.
A common misconception is most pathogenic bacteria are found in bathrooms. However, there are also bacteria on surfaces not commonly thought about such as desks, light switches, door handles, and hall passes. Most cleaning protocols have been formed around several general locations, with bathrooms being cleaned the most. By investigating which specific areas need more cleaning attention, the major misconception can be fixed. There are several dependent variables which affect the amounts and levels of certain bacteria. The location is a significant variable since differences in temperature and humidity may affect the growth of specific bacteria more than others. School-wide attendance also plays a key role. For instance, levels of bacteria may be different on a Monday compared to a Friday since Saturday and Sunday are unpopulated before Monday. The avoidance of cross-contamination is furthermore critical. If a swab or petri dish becomes contaminated by mistake, it cannot be used. Time and date may also be a dependent variable, depending on the location. For example, the exit doors are most commonly used at the beginning and end of the school day. It is likely levels will fluctuate during and between the usage times.
Due to the sensitivity of bacteria, there are several limitations and boundaries. Firstly, colony counts are rough, estimated numbers. Without the use of specialized equipment, all amounts of bacteria are determined as colony groups. While the estimations are stable enough for comparison, they are not perfect representations. Secondly, safety takes priority. Since a majority of the study is impacted by infectious bacteria, procedures must be followed for disposal when necessary. If a seriously dangerous bacterium such as MRSA were to be found while culturing, it would not be suitable for continued use. Growing large amounts of antibiotic-resistant bacteria is further dangerous. In the cases of harmful bacteria, their presence will be recorded but will not be continuously cultured. Thirdly, the study is confined to Williamston High School; no other buildings will be tested. As follows, only a limited number of surfaces can be tested as there is not enough time or resources to sample more than what has been planned.

Literature Review

In Andersson et al.’s (1998) study, it presents dust-borne bacteria in animal sheds, schools, and daycare centers. Of the bacteria, the article looks into Gram-positive and Gram-negative bacteria, as well as the exotoxins produced. In the end, \”dusts from schools and children\’s day care centres contained 0.2-0.3 ng of endotoxin mg-1 and 0.5-1.4 ng of β-D-glucan mg-1\” (Anderson et al., 1998). In most cases, endotoxins are dangerous to the health of humans and animals. Before reviewing this article, endotoxins were not accounted for. More or less, the focus point was mostly on the types and amounts of bacteria. However, endotoxins may still be considered. The tables used to display data were a good example of how to organize results. Bacteria were categorized into Gram-positive, Gram-negative, and neither, followed by being ordered alphabetically. Then, the colony forming units were listed for both within the air and settled dust. A similar type of table and results sections has been considered from this study.1
Archibald et al.’s (2008) article analyzed MRSA in a college locker room after a player had a positive test for MRSA, or Methicillin-resistant Staphylococcus aureus. While S. aureus alone is a pathogenic bacterium, the “MR” part makes it resistant to Methicillin and other antibiotics. For that reason, it is becoming difficult to treat, and more measures are being taken to prevent infection. It would not have been surprising to find MRSA within a school, especially in the locker rooms and on gym surfaces. The study used nasal swabs to cultivate bacteria and determine if a player or staff member had the S. aureus bacterium. While a nasal swab could be beneficial to determining if people were infected, it does not focus specifically on infection from the environment. Also, a nasal swab would include the requirement of finding volunteers and having enough experience to complete such a test. Before protocols were issued to prevent MRSA were implicated, 3.7% of students and 7.9% of staff tested positive. After the new disinfecting protocols had been released, only 1.4% of students remained MRSA-positive. In this study, the data from the experiment was used to increase the awareness of a dangerous bacterium. The results showed the raised awareness of MRSA led to a drop in active cases. Being able to implicate data to reduce the number of infections of pathogenic bacteria would be an excellent achievement.2
Garret et al.’s (2008) research investigates the impact of bacterial biofilms. When bacteria live on a surface, it is usually either planktonic or sessile. Planktonic bacteria tend to be unrestrained while sessile are attached to a surface via a biofilm. Previously, the impact of biofilms was not account for; but in fact, they play a fundamental role in the survival of the bacteria. They also affect the effectiveness of many cleaning agents. According to this study, a biofilm is similar to a protective layer which harbors bacteria. Usually, the biofilm will be attached to a surface and contain adhered bacteria. Around 99% of surface bacteria are in a biofilm form at some point. Not knowing what a biofilm was previously, the information in the article is critical. In the end, biofilms may support a claim regarding better disinfecting procedures. A significant advantage to bacteria living within a biofilm is the protective qualities. Biofilms protect bacteria, “[from] antibiotic, disinfectants, and dynamic environments” (Garrett et al., 2008). These protective biofilms may prevent surfaces from being cleaned as effectively as they could be cleaned. The study also notes since biofilms prevent many surfaces from being properly disinfected, many cases of food poisoning are caused by them. Biofilms may play a crucial role in the development of bacteria in schools, as they impact the effectiveness of disinfectants used.3
Gazi et al.’s (2004) study is focused on bacteria within students, which they may spread to other students and surfaces in the school. It also included data about the risks of antibiotic resistant bacteria, which make drugs less effective when people are sick. However, none of these experiments can be safely or legally re-conducted. To determine the types of bacteria students had, throat swabs were used. Not only would finding volunteers be difficult, but there are too many restrictions on human testing. While this study looks into bacteria harbored inside the human body, the external bacteria would be an easier subject. The results had proven a large number of students had pathogenic bacteria in their upper respiratory tract but did not display symptoms. However, these bacteria can be dispersed into the air, onto objects, and transmitted by the hands. While internal bacteria may not be testable, what has been found in the school environment can be compared to what is found in the upper respiratory tract. In an additional part, the study looks into which bacteria were resistant to antibiotics. Almost 25% of the bacteria were found to be resistant to Penicillin, one of the most common drugs used for URIs and strep throat. While looking into the resistance would have been interesting, it would not have been effective. To study antibiotic resistance in bacteria, there are many laws and restrictions to do so. -It is also unsafe to do so. All in all, it was still shocking 25% of bacteria cultures were resistant to Penicillin. Although antibiotic resistant bacteria will not be cultured on purpose, it was likely to be found in a public environment.4
Hurst’s (n.d) study followed multiple experiments to address various hypotheses. Of the experiments, bacteria were cultivated and identified, DNA was sequenced for PCR, bacterial pigmentation, and the copper effect were all evaluated. While the single study covers four topics, it would be far better to focus on one main point. The study became a run-on and should have been separated. Of the four major experiments, the most useful part regarded bacterial cultivation and identification. The issues with going into DNA sequencing and pigmentation is the availability of technology. These tests often require high-end equipment, software, and skills. To carry out the bacterial identification and count, the investigation focused on collection and cultivation of bacteria. To effectively cultivate and count, procedures must be followed carefully. One variable was cultivation temperature. To mimic the environment, the cultivation temperature should be the same. In this case, room temperature. The study also cultivated at the internal human body temperature to experiment with bacteria living within people. A fascinating find was also made in the study. When cultivating bacteria, Kaistella sp. was discovered. However, Kaistella sp. was foreign to Luxembourg and native to South Korea. Ironically, there was a native South Korean student who tested positive for Kaistella sp. The study suspects the bacterium was carried from South Korea to the school by the student, and later mutated DNA to suit better the foreign environment. Being able to trace a particular bacterium back to a region, followed by a specific person, would have been an outstanding discovery.5
In Meadow et al.’s (2014) article, it presents information regarding bacterial communities within classrooms, including whether the numbers and types vary with human contact. Given as background information, the composition of microbial communities was formed based on constraints in the environment and method of dispersion. Would the type of surface impact the amounts and types? From this background, it would. It has also been noted, “If dispersal from human is a major determinant, then community structure should vary with frequency and nature of human contact” (Meadow et al., 2014). In the case of a school environment, human nature is an essential component. By understanding how persons physically act, knowledge can be learned to the point of which surfaces are most likely to contain bacteria. A valid point of, “It is not whether more indirect skin-to-surface contact… might result in similar bacterial transmission” (Meadow et al., 2014), must also be considered. It would be interesting to have seen if indirect contact, such as sitting in chairs, had any impact. To perform an unbiased experimentation, many procedures were followed. First, classrooms were occupied daily for a full week before experimentation. The classrooms were also used on the day of testing. This protocol might be a major factor as some lifespans of bacteria would not last long enough. Second, samples were taken in multiple locations of the room to prevent CFU (colony forming unit, or an estimated number of viable bacteria) outliers. Thirdly, all surfaces were visibly clean with no standing dust. However, why not test the area, even if it appears dirty or dusty? After all, the dust could contain bacteria, which would add to the theory. Following collection, rRNA was analyzed to determine the types and amounts of bacteria. Since rRNA procedures are expensive, time consuming, and require a vast knowledge of microbiology, the likelihood of use is low. The study determined human interaction resulted in the transfer of bacteria from people to the surfaces. It was also determined transmission was possible, even if contact was indirect.6
As determined by Ray et al.’s (2011) research, hand washing is a key element in preventing the spread of bacteria and other microorganisms. A surface cannot become infectious without first being infected. Human contact is a significant aspect for bacteria, including location, types, and amounts. Hand washing could significantly impact the research conducted. Since most of the bacteria found in a school are due to human contact, an understanding of hand washing is necessary. In the study carried out by the Indian Public Health Association, many pathogenic bacteria were identified on students’ hands, including E. coli, staph infections such as Staphylococcus aureus, Salmonella sp., and Pneumococci Group A. It is shocking to know the number of pathogenic bacteria on hands alone. There were some other bacteria; however, they were non-pathogenic. Since many of the identified bacteria are on the hands of students, they are likely to be on other surfaces. A note has been taken of the particular strains, as they were liable to be found.7
Wang’s (2007) study focuses on pathogenic microorganisms which are threats inside school buildings. Experiments consisted of CFUs to determine the levels of three types of organisms: bacteria, molds, and yeasts. However, this study focuses on a wider array of microorganisms than bacteria alone. Highlighted in the introduction, it was noted only a small percentage of these microorganisms are pathogenic. Experimentation was composed of the collection, identification, quantity, and categorization of bacteria. A similar process would be practical and informative. Collection consisted of using sterile swabs, water, and products, to prevent cross-contamination. To determine the quantity, a CFU was used. To determine the CFU accurately, the experiment used a product called Petrifilm, made by 3M. Petrifilm will be investigated, as it may save time and be more accurate. Noted in the results, a significant amount of Staphylococcus aureus was identified. Since, “S. aureus is known to cause pneumonia, septicemia, and toxic shock syndrome,” (Wang, 2007) certain precautions have been taken while experimenting. Although these pathogens are less hazardous in smaller quantities, cultivating larger amounts may pose a health hazard. From this, it would have been worth using certain protective equipment, such as gloves, and to wash hands frequently while handling. Personal protective equipment may also aid in the prevention of cross-contamination.8


Sample Population
Three classrooms from Williamston High School have been chosen for sampling. These classrooms include a science laboratory, mathematics classroom, and a history classroom. Respectively, they have been named Sample Room One, Sample Room Two, and Sample Room Three. All classrooms contain: a door, light switches, hall pass, and pencil sharpener. Classroom specific, Sample Room One is equipped with sinks, laminate flooring, non-porous laboratory desks, and porous plastic laboratory chairs. Sample Room Two and Three have carpet flooring, laminate/artificial semi-porous wood desks, and porous plastic chairs. The term ‘porous’ is relating to whether the surface is smooth, somewhat smooth, or rough. Each classroom is populated daily, with students in the classroom four of six periods.
Cultures were grown using standard nutrient agar and 100mm x 15mm sterile petri dishes. The nutrient agar is stored in dehydrated form, but must be prepared into a gel-form. To create the gel medium, 200mL of distilled water is mixed with 4.6g of dehydrated nutrient agar. The mixture is boiled for one minute, given several minutes to cool, and is then poured into sterile petri dishes. The prepared plates are stored in the refrigerator to prevent bacterial growth and spoilage of the agar. Each petri dish is inverted to prevent the formation of condensation on the agar surface.
Culturing of the surface bacteria is done so by taking a sterile cotton swab, rubbing the swab on the surface for thirty seconds, followed by inoculation on a prepared nutrient agar petri dish at room temperature. Inoculation of the agar is completed by producing zig-zag lines on the agar surface. To prevent cross contamination, gloves and a mask are worn. The petri dish is then given a unique identification number which corresponds with information recorded on a computer. Recorded information connected to the identification number includes: date/time of sample, specific location, room location, and any dish-specific notes. Following inoculation and recording, it is moved into an incubator heated to 37 degrees Celsius. By heating to human body temperature, pathogenic/illness-causing bacteria favor the conditions.9 The inoculator is kept out of direct sunlight and disturbances. Following 48 hours of incubation, the petri dishes are removed. Due to the nature of pathogenic bacteria, gloves and a mask are equipped. A photograph of the petri dish is taken alongside the identification number and a ruler for colony size reference. The photograph is then uploaded to the computer where it corresponds with the identification number and sample information. Each petri dish is counted for the number of colonies grown; the number is then recorded. Disposal of used petri dishes is done so by decontamination with concentrated chlorine bleach, sealing, and placement into a biohazardous waste receptacle.
Experimentation is broken into two phases. Phase I focuses on determining the levels of bacteria on seven commonly touched surfaces: chairs, desks, door handles, floors, hall passes, light switches, and pencil sharpeners. Using the culturing and inoculation procedure as explained, samples were examined for the number of colonies grown post-incubation. To effectively count the number of colonies, pictures are taken of each sample. The pictures are then uploaded to the computer and counted using a digital pen to ensure accuracy.
Phase II focuses on the effectiveness of disinfecting wipe use on student desks. The desks from each sample room are tested for three days. The procedure consists of first sampling the desk, disinfecting with a disinfectant wipe, and waiting 24 hours to repeat the sample. Samples are taken for a total of three days from each sample room. On the first day, a sample is collected to note the start bacterial count. The desks are then wiped with a Clorox® brand disinfecting wipe. Twenty-four hours later, the desks are resampled. Forty-eight hours following the initial sample, another sample was collected. Each sample follows the standard methodology of inoculation, incubation, and examination.


Demonstrated by Table 1 is the number of colony counts per sample, per location, per sample room. Each sample room contained seven surfaces which underwent biological sampling. To form a more ideal bacterial count, samples from each surface are taken twice, each occasion being noted under “Test Occurrence.” With two separate occurrences, the mean is taken to produce the average colony count for the surface.

Phase I: Sample Colony Counts
Table 1
Source Room Sample Location Test Occurrence Occurrence Colony Count Mean Colony Count
Sample Room 1 Student Chair 1 32 88
2 144
Student Desk 1 187 198
2 208
Door Handle 1 16 24
2 31
Floor 1 182 147
2 112
Hall Pass 1 0 0
2 0
Light Switch 1 9 7
2 5
Pencil Sharpener 1 48 43
2 38
Sample Room 2 Student Chair 1 16 16
2 16
Student Desk 1 24 86
2 148
Door Handle 1 206 112
2 17
Floor 1 32 37
2 41
Hall Pass 1 2 3
2 4
Light Switch 1 3 3
2 2
Pencil Sharpener 1 29 15
2 1
Sample Room 3 Student Chair 1 27 19
2 11
Student Desk 1 31 69
2 107
Door Handle 1 47 33
2 19
Floor 1 69 39
2 9
Hall Pass 1 79 81
2 83
Light Switch 1 7 7
2 6
Pencil Sharpener 1 2 1
2 0

Established by Table 2 is the number of colony counts per sample, per desk, per sample room following the disinfection procedure. Test occurrence one had no disinfection, occurrence two had a single disinfection 24 hours prior, and occurrence three had two disinfection events 24 hours and 48 hours prior.

Phase II: Effectiveness of Disinfecting
Table 2
Source Room Sample Location Test Occurrence Occurrence Colony Count
Sample Room 1 Student Desk 1 199
2 178
3 151
Sample Room 2 Student Desk 1 113
2 87
3 69
Sample Room 3 Student Desk 1 87
2 62
3 51


In conclusion, there is a strong level of support proving certain areas in the classroom must be regularly disinfected. Further, it has also been proven the use of disinfecting wipes daily on student desks is an effective method of decreasing bacterial levels. With Sample Room One, the use of disinfecting wipes reduced bacteria on student desks by more than 24%. Sample Room Two saw more than a 39% decrease and Sample Room Three saw an outstanding 41% decrease. Knowing the disinfection procedure reduced bacteria between 24% and 41% over a three-day stretch is an exceptional result and an effective motivator to use the method in a multitude of settings.
Although none of the reviewed literature contained a similar study, the findings are concrete. All of the evidence in support of the results came from samples and cultures within the sample rooms. Each and every sample was treated the same way in terms of the collection, inoculation, and incubation to prevent as much variance as possible. By following a strict methodology, the results are accurate to support the claims.
Some limitations do apply to the results given. While several surfaces have been flagged as hotspots, there are hundreds of other surfaces within schools that have just as much contact and possibly more bacteria. However, based on the amount of allotted time and resources, only so many samples could be collected. Regarding the surfaces that were tested, numbers can always fluctuate –especially with live organisms such as bacteria. There are so many factors which go into bacterial development and not all of them can be accounted. Bacterial counts may be higher or lower, day to day, based upon levels of human contact, environmental conditions, janitorial conditions, and other factors. Many of these factors cannot be controlled. Keeping a steady environment or level of contact is impossible. Even if a bacterial count is low on a given day, it does not illustrate a steady statistic.
All in all, the knowledge learned can be applied immediately to any school. Now with the understanding of where hidden numbers lie, surfaces previously thought of as clean can now be exposed to janitorial staff. Students and staff now have an incentive to clean student desks. By cleaning the desks with an antibacterial agent or disinfecting wipe, harmful bacterial levels can be cut significantly. Therefore, student and staff health can be significantly improved.
However, this research does not provide the answer to each and every bacterial problem in schools. Future research is vital to improving the health and well-being of people who are in constant contact with a school environment. More information still needs to be understood about other sources of bacteria, which specific bacteria are existent, and if there are stronger or more efficient measures to reduce it.