In recent studies, copper’s antimicrobial properties have been studied in hospitals where infections spread from contact with high-touch surfaces are common, oftentimes using high expensive and advanced equipment. While these methods of analysis are not readily available for those in smaller laboratories or in classrooms; this research project aims to analyze copper alloys’ antimicrobial properties compared to stainless steel, using a procedure that can be easily replicated and expanded upon. To test copper alloys’ effectiveness, I first had to collect samples from traditional dumbbells and analyze if microbes were present on the weights. These samples were collected and analyzed for the presence of microbes. For the in-lab part, a ten-fold serial dilution was used to make the number of bacterial colonies present quantifiable; this method used non-pathogenic Escherichia coli. Both the copper and stainless-steel metals were incubated for 15 minutes to mimic the amount of time an individual would spend with a specific weight. After the incubation, the metal pieces were taken out of the solution and dried on a sterile plate for 15 minutes. After the drying period, the metals were placed into PBS baths and immersed for 10 minutes to recover bacteria. After the PBS bath, the ten-fold dilution was performed and then plated and incubated at 37˚C for 24 hours. Once the 24-hour period was over, the colonies on the plates of both the copper and stainless-steel plates were counted, and it was determined that the plates of the copper metal had significantly fewer colonies.
95% Ethanol is commonly found to be one of the main active ingredients in most alcohol wipes, which are commonly used to disinfect the skin before a vaccination. The objective of this study was to determine the effect of contact time on the recovery of bacteria from a surface. Overnight cultures of E. coli were spotted glass slides and allowed to dry. Filter paper squares saturated with 95% ethanol were applied to the bacterial spots for varying amounts of time (10, 20, 40 and 80 seconds). After removing the filter paper 100 ul of sterile water was applied to the slide, and immediately 50 ul was removed and serially diluted to determine the number of bacteria recovered from the slide. As expected majority of the results showed that the eighty-second ethanol exposure time had the lowest number of bacterial colonies recovered. Unexpectedly, the water control (sterile water on filter paper) had an even lower number bacterial of colonies recovered when compared to the ethanol treatments. Overall, the trials performed with water were the most effective at reducing the number of bacteria recovered.
Antibiotics are routinely used as growth promoters in livestock where they help animals gain weight faster or use less food to gain weight. Since any use of antibiotics is known to increase antibiotic resistance we wanted to see if an increase in antibiotic resistance organisms could be detected using simple microbiological techniques, with an eye toward using this in an introductory microbiology lab course. Saliva samples were taken weekly from an isolated group of cattle before and after the addition of a chlortetracycline containing feed supplement to their diet. Samples were serially diluted and plated onto TSA and TSA + tetracycline agar plates. Antibiotic resistant bacteria were isolated from day 1 and their numbers remained relatively consistent throughout the trial. The proportion of antibiotic resistant organisms increased markedly following the addition of the medicated supplement. Potential applications in a microbiology course will be discussed.
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