RT Journal Article SR Electronic(1) A1 Donker, Tjibbe A1 Reuter, Sandra A1 Scriberras, James A1 Reynolds, Rosy A1 Brown, Nicholas M. A1 Török, M. Estée A1 James, Richard A1 Network, East of England Microbiology Research A1 Aanensen, David M. A1 Bentley, Stephen D. A1 Holden, Matthew T. G. A1 Parkhill, Julian A1 Spratt, Brian G. A1 Peacock, Sharon J. A1 Feil, Edward J. A1 Grundmann, HajoYR 2017 T1 Population genetic structuring of methicillin-resistant Staphylococcus aureus clone EMRSA-15 within UK reflects patient referral patterns JF Microbial Genomics, VO 3 IS 7 OP SP e000113 DO https://doi.org/10.1099/mgen.0.000113 PB Microbiology Society, SN 2057-5858, AB Antibiotic resistance forms a serious threat to the health of hospitalised patients, rendering otherwise treatable bacterial infections potentially life-threatening. A thorough understanding of the mechanisms by which resistance spreads between patients in different hospitals is required in order to design effective control strategies. We measured the differences between bacterial populations of 52 hospitals in the United Kingdom and Ireland, using whole-genome sequences from 1085 MRSA clonal complex 22 isolates collected between 1998 and 2012. The genetic differences between bacterial populations were compared with the number of patients transferred between hospitals and their regional structure. The MRSA populations within single hospitals, regions and countries were genetically distinct from the rest of the bacterial population at each of these levels. Hospitals from the same patient referral regions showed more similar MRSA populations, as did hospitals sharing many patients. Furthermore, the bacterial populations from different time-periods within the same hospital were generally more similar to each other than contemporaneous bacterial populations from different hospitals. We conclude that, while a large part of the dispersal and expansion of MRSA takes place among patients seeking care in single hospitals, inter-hospital spread of resistant bacteria is by no means a rare occurrence. Hospitals are exposed to constant introductions of MRSA on a number of levels: (1) most MRSA is received from hospitals that directly transfer large numbers of patients, while (2) fewer introductions happen between regions or (3) across national borders, reflecting lower numbers of transferred patients. A joint coordinated control effort between hospitals, is therefore paramount for the national control of MRSA, antibiotic-resistant bacteria and other hospital-associated pathogens., UL https://www.microbiologyresearch.org/content/journal/mgen/10.1099/mgen.0.000113