The stealthy superbug: the role of asymptomatic enteric carriage in maintaining a long-term hospital outbreak of ST228 methicillin-resistant Staphylococcus aureus

Laurence Senn, Olivier Clerc, Giorgio Zanetti, Patrick Basset, Guy Prod'hom, Nicola Gordon, Anna Sheppard, Derrick Crook, Richard James, Harry Arthur Frank Wright Thorpe, Edward Feil, Dominique Blanc

Research output: Contribution to journalArticle

36 Citations (Scopus)
44 Downloads (Pure)


Whole-genome sequencing (WGS) of 228 isolates was used to elucidate the origin and dynamics of a long-term outbreak of methicillin-resistant Staphylococcus aureus (MRSA) sequence type 228 (ST228) SCCmec I that involved 1,600 patients in a tertiary care hospital between 2008 and 2012. Combining of the sequence data with detailed metadata on patient admission and movement confirmed that the outbreak was due to the transmission of a single clonal variant of ST228, rather than repeated introductions of this clone into the hospital. We note that this clone is significantly more frequently recovered from groin and rectal swabs than other clones (P < 0.0001) and is also significantly more transmissible between roommates (P < 0.01). Unrecognized MRSA carriers, together with movements of patients within the hospital, also seem to have played a major role. These atypical colonization and transmission dynamics can help explain how the outbreak was maintained over the long term. This “stealthy” asymptomatic colonization of the gut, combined with heightened transmissibility (potentially reflecting a role for environmental reservoirs), means the dynamics of this outbreak share some properties with enteric pathogens such as vancomycin-resistant enterococci or Clostridium difficile.
Original languageEnglish
Article numbere02039-15
Pages (from-to)1-9
Number of pages9
Issue number1
Early online date19 Jan 2016
Publication statusPublished - 28 Feb 2016

Cite this