Longitudinal genomic surveillance of MRSA in the UK reveals transmission patterns in hospitals and the community

Longitudinal genomic and epidemiological surveillance of methicillin-resistant Staphylococcus aureus in the UK reveals extensive transmission in hospitals and the community. On the trail of MRSA Genome sequencing of methicillin-resistant Staphylococcus aureus (MRSA) has been successfully applied to investigate suspected outbreaks. Coll et al. now extend its application to the genomic surveillance of MRSA in samples from 1465 people identified over a 12-month period by a diagnostic laboratory in the East of England. This analysis identified 173 putative outbreaks involving 598 patients and included hospital outbreaks, those spanning the hospital and community, and community outbreaks among people registered with the same medical practice or living in the same household or long-term care facility. This study illustrates that sequencing is a powerful tool that could be used to identify infectious disease outbreaks as they happen. Genome sequencing has provided snapshots of the transmission of methicillin-resistant Staphylococcus aureus (MRSA) during suspected outbreaks in isolated hospital wards. Scale-up to populations is now required to establish the full potential of this technology for surveillance. We prospectively identified all individuals over a 12-month period who had at least one MRSA-positive sample processed by a routine diagnostic microbiology laboratory in the East of England, which received samples from three hospitals and 75 general practitioner (GP) practices. We sequenced at least 1 MRSA isolate from 1465 individuals (2282 MRSA isolates) and recorded epidemiological data. An integrated epidemiological and phylogenetic analysis revealed 173 transmission clusters containing between 2 and 44 cases and involving 598 people (40.8%). Of these, 118 clusters (371 people) involved hospital contacts alone, 27 clusters (72 people) involved community contacts alone, and 28 clusters (157 people) had both types of contact. Community- and hospital-associated MRSA lineages were equally capable of transmission in the community, with instances of spread in households, long-term care facilities, and GP practices. Our study provides a comprehensive picture of MRSA transmission in a sampled population of 1465 people and suggests the need to review existing infection control policy and practice.