Carriage Rates of Methicillin-Resistant Staphylococcus aureus (MRSA) Among College Students Ryan Kitzinger, Leigh Nelson, Chad Sethman, Ph.D. ABSTRACT Discovered in 1881 by Dr. Alexander Ogston, M.D., Staphylococcus aureus is a Gram- Positive cocci that has since emerged as one of the most medically significant pathogens. Recent studies suggest S.aureus has reached epidemic levels, and now asymptomatically colonizes approximately 30% of the population at any given time. S.aureus has also developed into one of the most common resistant pathogens, with greater than 50% of all community-acquired S.aureus infections being caused by a MRSA strain in some populations. Previous studies have suggested that individuals who engage in contact sports are at an increased risk for the transmission of MRSA. This increase is thought to come from the physical contact and increased risk for skin abrasion, as well as the sharing of improperly sanitized athletic equipment and facilities. Prior research has also suggested that there is a significant rise in risk in MRSA contraction among healthcare workers due to the frequent exposure to disease which is associated with the profession. Based on these findings, it was hypothesized that college students engaging in these activities (contact sports and nursing clinicals) would have the highest risk of S. aureus and MRSA contact, and would thus demonstrate a higher prevalence of S.aureus and MRSA carriage. Nasal swabs of student participants were screened for the presence of S. aureus, which was characterized by its resistance to methicillin. Each subject also completed a brief questionnaire, with special attention given to the identification of potential risk factors and assessment of public health awareness. Our data reveals that football players are more likely to carry S. aureus, but the prevalence of MRSA in this group is significantly lower than the control group. We also show that carriage rates among nursing students were comparable to a control population with 26.9 percent S. aureus carriage rate and 10.5 percent MRSA carriage rate. BACKGROUND S. aureus can be harmlessly carried as normal flora primarily in the anterior nares. S. aureus is a common cause of infections ranging from mild skin infections to severe, invasive infections. Methicillin resistance, facilitated by the MecA gene, can complicate treatment and prolong disease and recovery Previous research has suggested persons engaged in contact sports have an increased risk for MRSA carriage Previous research has also shown that healthcare workers have one of the highest rates of MRSA This research aims to address risk factors for MRSA carriage among groups of college students, and also assess public health awareness of MRSA METHODS Mannitol salt agar (MSA) was used to differentiate S. aureus from other nasal flora based on a yellowing of the medium indicating mannitol fermentation (fig. 1) Growth on MSA supplemented with methicillin was used to indicate methicillin resistance RESULTS ACKNOWLEDGEMENTS We would like to thank Dr. Chad Sethman for his advice throughout the course of this study, Dr. James Bush for his assistance in data analysis and the Waynesburg University Center for Research and Economic Development for their financial support. CONCLUSIONS Football Players are at an increased risk for S.aureus carriage, however rates of MRSA carriage were much lower than controls. Increased activity levels appear to reduce the risk for MRSA carriage. This phenomenon will have to be investigated in more detail. Use of athletic/fitness facilities may be correlated with S. aureus carriage but the risk for MRSA carriage is not evident. Neither hospital work nor clinical exposure appear to be correlated with MRSA carriage risk in this study. More detailed investigation will be required to elucidate this correlation. Figure 1. Growth of S. aureus on MSA Table 1. Survey questions used in this study. Percent of S. aureus and MRSA-colonized individuals as a correlate of survey answers. Questions are arranged according to odds ratio from highest to lowest. * indicates p <0.05. Figure 2. S. aureus and MRSA carriage rates for individual student groups. Figure 3. Prevalence of MRSA among S. aureus isolates in various student groups. Figure 4. Prevalence of MRSA carriage in two groups defined by activity level. Figure 5. Prevalence of MRSA carriage in groups representing increasing time spent utilizing athletic/fitness facilities. Figure 6. Prevalence of S. aureus and MRSA carriage in hospital workers/volunteers. Figure 7. Prevalence of MRSA carriage in groups representing increasing time spent in nursing clinicals. Figure 8. Prevalence of S. aureus and MRSA carriage in male students versus female students.