Dominance of EMRSA-15 and -16 among MRSA causing nosocomial bacteraemia in the UK: analysis of isolates from the European Antimicrobial Resistance Surveillance System (EARSS)

Abstract

Sir, The scale of the public health problem posed by methicillin-resistant Staphylococcus aureus (MRSA) in England and Wales increased significantly during the 1990s. Most dramatically, the proportion of cases of S. aureus bacteraemia due to MRSA increased from 1–2% in 1990–1992 to c. 40% in 2000.1–3 This increase coincided with the emergence of two particular epidemic MRSA (EMRSA) strains, EMRSA-15 and EMRSA-16,4 which now dominate MRSA submissions to the S. aureus Reference Service (SaRS) of the Laboratory of Hospital Infection.5 Nevertheless, EMRSA-15 and -16 have not formally been shown to be the principal agents of MRSA bacteraemia in the UK. Increasing MRSA prevalence rates have also been documented in many other countries. In response to widespread concern about resistance, the European Commission (Directorate General V) has funded pan-European surveillance of resistance. This programme, designated the European Antimicrobial Resistance Surveillance System (EARSS), currently has participants from all countries of the EU, plus Iceland, Norway and Switzerland.6 Since its commencement in late 1998, EARSS has focused on MRSA from nosocomial bacteraemia and penicillin-resistant pneumococci from community-acquired bacteraemia or meningitis. In the participating countries, data are collected from sentinel laboratories by national co-ordinators, then submitted to a central database maintained at the National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands. As methods of susceptibility testing vary between participating laboratories, the laboratories are encouraged, where possible, to obtain MIC data.