PT - JOURNAL ARTICLE AU - Amy C. Dupper AU - Mitchell J. Sullivan AU - Kieran I. Chacko AU - Aaron Mishkin AU - Brianne Ciferri AU - Ajay Kumaresh AU - Ana Berbel Caban AU - Irina Oussenko AU - Colleen Beckford AU - Nathalie E. Zeitouni AU - Robert Sebra AU - Camille Hamula AU - Melissa Smith AU - Andrew Kasarskis AU - Gopi Patel AU - Russell B. McBride AU - Harm van Bakel AU - Deena R. Altman TI - Blurred molecular epidemiological lines between the two dominant methicillin-resistant <em>Staphylococcus aureus</em> clones AID - 10.1101/501833 DP - 2019 Jan 01 TA - bioRxiv PG - 501833 4099 - http://biorxiv.org/content/early/2019/09/18/501833.short 4100 - http://biorxiv.org/content/early/2019/09/18/501833.full AB - Background Methicillin-resistant Staphylococcus aureus (MRSA) causes life-threatening infections in both community and hospital settings and is a leading cause of healthcare-associated infections (HAIs). We sought to describe the molecular epidemiological landscape of patients with MRSA bloodstream infections (BSIs) at an urban medical center by evaluating the clinical characteristics associated with the two dominant endemic clones.Methods Comprehensive clinical data extraction from the electronic health records of 227 hospitalized patients ≥18 years old with MRSA BSI over a 33-month period in New York City were collected. The descriptive epidemiology and mortality associated with the two dominant clones was compared using logistic regression.Results Molecular analysis revealed that 91% of all single-patient MRSA BSIs were due to two equally represented genotypes, clonal complex (CC) 5 (N=117) and CC8 (N=110). MRSA BSIs were associated with a 90-day mortality of 27%. CC8 caused disease more frequently in younger age groups (56 ± 17 vs 67 ± 17 years old; p&lt;0.001) and in non-White race (OR=3.45 95% CI [1.51-7.87]; p=0.003), with few other major distinguishing features. Morbidity and mortality also did not differ significantly between the two clones. CC8 caused BSIs more frequently in the setting of peripheral intravenous catheters (OR=5.96; 95% CI [1.51-23.50]; p=0.01).Conclusion The clinical features distinguishing dominant MRSA clones continue to converge. The association of CC8 with peripheral intravenous catheter infections underscores the importance of classical community clones causing hospital-onset infections. Ongoing monitoring and analysis of the dynamic epidemiology of this endemic pathogen is crucial to inform management to prevent disease.