1. Efficacy of Cotton Sheets as a Barrier Against Bacterial Transmission in Hospital Environments Nikol Ann Rainwater and Carolyn Mathur, Ph.D. Department of Biological Sciences, York College of Pennsylvania Department of Biological Sciences, York College of Pennsylvania Materials & Methods Petri dishes with vinyl and cotton squares stacked Introduction Hospitals and clinics commonly use cotton sheets as a barrier between patients and equipment, such as transportation equipment, mattresses, and exam tables. While it is assumed these surfaces are disinfected prior to being covered and used, it is possible that bacteria may still reside on them (Oie S., et al. 2005). If a cotton sheet is ineffective as a barrier it would be beneficial to be aware of the possibility of nosocomial infections (Boyce, J.M., et al. 1997). Due to the prevalence of nosocomial infections and the cost of treating such patients it is important to look at the efficacy of the use of cotton sheets as a barrier. Staphylococcus aureus is a coccus shape, and Klebsiella pneumoniae and Escherichia coli are rod shaped. The objective of this study is to simulate and test the efficacy of cotton sheets as barriers between patients and contaminated transportation equipment with bacteria commonly found in hospital environments. Additionally, this study investigates the possibility size and shape may play a role in bacterial transmission through cotton fibers. Hypothesis Results Conclusion The sheet was ineffective as a barrier when the culture or sheet was wet, but effective when both the culture and the sheet were left dry. However, previous research suggests a dry cotton sheet placed on dry cultures is ineffective when friction is applied. The data suggests the size and shape of the bacteria may play a role in the ability of the bacteria to transmit through the fibers of the cotton sheet. Efforts should be made to control bacteria transmission by increasing efforts to disinfect mattresses before a cotton sheet is used. Works Cited Barrett, S. P., Mummery, R. V., and Chattopadhyay, B. 1998. Trying to control MRSA causes more problems than it solves. Journal of Hospital Infection 39:85-93. Boyce, J. M., et al. 1997. Environmental contamination due to methicillin- resistant Staphlyococcus aureus: possible infection control implications. Infection Control and Hospital Epidemiology 18:622-627. Oie, S., et al. 2005. Contamination of environmental surfaces by Staphylococcus aureus in a dermatological ward and its preventative measures. Biological Pharmicological Bulletin 28:120-123. Sattar, S.A., Springthorpe, S., Mani, S., Gallant, M., Nair, R.C., Scott, E. and Kain, J. (2001), Transfer of bacteria from fabrics to hands and other fabrics: development and application of a quantitative method using Staphylococcus aureus as a model. Journal of Applied Microbiology, 90: 962–970. doi: 10.1046/j.1365-2672.2001.01347.x Discussion The sheet was ineffective as a barrier when the bacteria cultures were left wet on the vinyl, and when dried cultures were rewetted with sterile water. The sheet was effective as a barrier when the bacteria cultures were dried first and remained dry during sampling with the RODAC plate. Due to extreme variance in means of transmission between organisms and patient susceptibility, it is difficult to conclude if a positive result for the presence of a bacteria would result in a nosocomial infection. S. aureus showed a higher rate of transmission than E. coli and K. pneumoniae, which is made even more dangerous due to the capability of S. aureus to cause infections in skin lesions that would likely come in contact with the cotton sheet. Quality of cleaning and proper handwashing techniques are cited as the most effective control mechanisms for nosocomial infections (Barrett 1998). Due to the inefficacy of cotton sheets as a barrier medical facilities quality of cleaning techniques should be a primary focus in the fight against nosocomial infections. Replicate Organism Detection and Counting Plates (RODAC) Wet 10 uL of each bacteria culture diluted to 10 -3 pipetted on the vinyl square in the petri dish Cotton sheet placed over bacteria covered vinyl RODAC plate pressed on top of sheet instantly RODAC plate incubated overnight and colonies counted Dry 100 uL of each bacteria culture pipetted on the vinyl square in the petri dish Dried in the incubator for 1 hour Cotton sheet placed over the bacteria covered vinyl, and the lid of the petri dish was used as a base with the base inverted to apply light pressure to the sheet for optimal contact RODAC plate pressed on top of sheet at times 5, 10, 15, and 30 minutes RODAC plate incubated overnight and colonies counted Prepared overnight cultures of Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli. Prepared RODAC plates with nutrient agar Vinyl squares and cotton sheet squares cut and placed within a petri dish Re-Wet 100 uL of each bacteria culture diluted to 10 -3 pipetted on the vinyl square in the petri dish Dried in the incubator for 1 hour Cotton sheet placed over the bacteria covered vinyl and 100 uL sterile water was pipetted over the sheet RODAC plate pressed on top of sheet after 1 minute RODAC plate incubated overnight and colonies counted Bacterial colonies on RODAC plates Cotton sheets will be ineffective as a barrier against bacterial transmission for all methods; wet, dry, and re-wet. The S. aureus will transmit through the cotton sheet more effectively than the K. pneumoniae and E. coli due to it’s smaller size and coccus shape. sample surface nutrient agar RODAC plate Figure 1. Wet trials of bacteria transmission through cotton sheet. Error bars represent 95% CI. Kruskal- Wallis showed significance between E. coli and S. aureus. Figure 2. Re-wet trials of bacteria transmission through cotton sheet. Error bars represent 95% CI. Kruskal-Wallis showed significance between E. coli and S. aureus. Discussion Continued Research by Sattar et al. suggests the sheet is ineffective as a barrier once friction is applied, which simulates the effect a patient would have when sitting or laying on the sheet (Sattar, S.A., et al. 2001). As such, the results for the dry trial are void and should not be viewed as an indication of efficacy as a barrier.