183 Spatiotemporal Patterns and Social Determinants of Community-Associated Methicillin Resistant Staphylococcus aureus Skin and Soft Tissue Infections Among Emergency Department Patients in North Central Florida

Abstract

To investigate spatial and social demographic patterns of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) skin or soft tissue infection (SSTI) in patients presenting to the emergency department in North Central Florida. From August 2015-January 2017, pediatric and adult patients presenting to UF Health Shands Emergency Department in Gainesville, FL with an acute SSTI were prospectively enrolled in cross-sectional study. Both nasal and SSTI site specimens were collected and cultured for spa-typing. Geographic, social, medical, and other patient-level epidemiological data was collected. Department of Defense rural-urban classification system and 2010 Census data was used for spatial and geographic analysis. Multivariate analyses were conducted to test associations of determinants and microbiological result. 171 subjects were included, spanning 24 counties and 69 zip codes based on self-reported home residence. 121 (75.4%) of subjects enrolled reported living in rural zip codes. 50 (29.2%) subjects had MRSA positive wound cultures and 24 (14%) had MRSA positive nasal cultures. MRSA positive wound culture was associated with recent exposure to livestock (p=0.006) while nasal colonization of MRSA was associated with current alcohol consumption (p=0.041), current history of smoking (p=0.003), and antimicrobial soap use (p=0.024). Nasal colonization of MRSA or MSSA was a significant predictor of positive MRSA wound cultures (p=<0.001) and positive MSSA wound cultures (p=0.004), respectively. Subjects residing in rural zip codes were 2.6 (CI:1.07-6.33, p=0.033) times more likely to have MRSA positive wound cultures. There was no association between zip code classification and nasal MRSA colonization. The geographic distribution of CA-MRSA is not uniform and has a higher prevalence in less populated more rural areas, potentially highlighting a zoonotic association in CA-MRSA transmission. Although previous studies have also shown the association of nasal MRSA colonization and MRSA positive wound culture, this study suggests an association of nasal MSSA colonization and MSSA positive wound cultures which has not been previously well recognized. Associations with nasal MRSA colonization and social demographics provide insight to possible preventative therapies to reduce CA-MRSA infections. While the effectiveness of antimicrobial soaps are disputed and regulated, the possible promotion of nasal MRSA colonization due to use requires investigation. Genetic spa-typing analysis will provide further insight regarding spatiotemporal transmission across communities.