The purpose of this experiment was to investigate bacterial contamination on frequently touched surfaces around Santa Clara University’s campus. By swabbing nine different locations, including door handles, elevator buttons, and tables, and culturing the samples on petri dishes, the study aimed to identify which commonly touched surfaces contained the most germs and bacteria. Understanding bacterial presence in public spaces is important for maintaining hygiene and preventing the spread of illness, especially in areas with high foot traffic. Many people may not consider how much bacteria accumulates on everyday objects, making studies like this valuable for raising awareness about cleanliness. The results of this experiment can also provide insight into which surfaces may require more frequent or thorough sanitation. Additionally, the findings may encourage individuals to adopt better hygiene practices, such as washing their hands more often or being mindful of what they touch before eating or touching their face. By identifying areas that may be overlooked by the cleaning crew, this study contributes to a broader understanding of how bacteria spread in shared environments and how they can be better managed.
A list of frequently touched but less frequently cleaned surfaces was created for sampling, focusing on areas with high foot traffic and frequent human contact. These locations were chosen based on their likelihood of harboring bacteria due to continuous use throughout the day. To collect bacterial samples, agar petri dishes and sterile swabs were used. Each swab was first dipped in bottled water to ensure proper collection, then firmly rubbed across the selected surface in a consistent motion to pick up any bacteria present. The swab was then immediately transferred onto a petri dish using a streaking technique to evenly distribute the sample. After swabbing, each petri dish was labeled with the corresponding surface name to ensure accurate identification. To promote optimal bacterial growth, the dishes were securely taped together to prevent contamination and placed in a warm, dark environment, mimicking conditions that allow bacteria to thrive. This step was crucial in ensuring that any bacteria collected had the opportunity to multiply and form visible colonies. After five days, the petri dishes were carefully examined, and the bacterial growth was analyzed. Instead of measuring the total area covered by bacteria, the number of distinct bacterial colonies, visible as small dots on the agar, was counted. This method allowed for a more precise comparison of contamination levels across different surfaces, as some bacteria spread out while others grow in defined clusters.
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Results show a clear variation in bacterial contamination across different surfaces, with some areas harboring significantly more bacteria than others. The sink handle/soap dispenser had the highest bacterial count, with 325 colonies, which is particularly interesting given that it is a location where people go to wash their hands. This suggests that while handwashing removes bacteria from the skin, the act of turning the sink on and off or dispensing soap may contribute to bacterial buildup, especially if the area is not cleaned frequently.
The soda machine in Benson (227 colonies) and SmartPrint station (209 colonies) also exhibited high levels of bacterial growth, likely due to frequent use by numerous individuals throughout the day. These surfaces are touched repeatedly, often without individuals considering their cleanliness, making them prime locations for bacterial accumulation. Additionally, these areas may not be sanitized as often as other high-contact surfaces, allowing bacteria to thrive.
Surprisingly, the library tables (83 colonies) and Swig elevator buttons (97 colonies) had more bacterial growth than commonly suspected dirty surfaces like door handles. People might assume that door handles, such as those on bathroom doors, would have higher contamination levels due to constant contact. However, the results indicate that shared study spaces and elevator buttons, which are touched by many people but may not be cleaned as frequently, can serve as unexpected hotspots for bacterial presence. These findings highlight the importance of regular surface cleaning, particularly in areas where students and faculty gather, as well as increased awareness about the unseen bacteria that accumulate on everyday objects.