title: High genetic diversity among community-associated Staphylococcus aureus in Europe: results from a multicenter study.
abstract: BACKGROUND
  Several studies have addressed the epidemiology of community-associated Staphylococcus aureus (CA-SA) in Europe; nonetheless, a comprehensive perspective remains unclear. In this study, we aimed to describe the population structure of CA-SA and to shed light on the origin of methicillin-resistant S. aureus (MRSA) in this continent.
  
  
  RESULTS
  A total of 568 colonization and infection isolates, comprising both MRSA and methicillin-susceptible S. aureus (MSSA), were recovered in 16 European countries, from community and community-onset infections. The genetic background of isolates was characterized by molecular typing techniques (spa typing, pulsed-field gel electrophoresis and multilocus sequence typing) and the presence of PVL and ACME was tested by PCR. MRSA were further characterized by SCCmec typing. We found that 59% of all isolates were associated with community-associated clones. Most MRSA were related with USA300 (ST8-IVa and variants) (40%), followed by the European clone (ST80-IVc and derivatives) (28%) and the Taiwan clone (ST59-IVa and related clonal types) (15%). A total of 83% of MRSA carried Panton-Valentine leukocidin (PVL) and 14% carried the arginine catabolic mobile element (ACME). Surprisingly, we found a high genetic diversity among MRSA clonal types (ST-SCCmec), Simpson's index of diversity = 0.852 (0.788-0.916). Specifically, about half of the isolates carried novel associations between genetic background and SCCmec. Analysis by BURP showed that some CA-MSSA and CA-MRSA isolates were highly related, suggesting a probable local acquisition/loss of SCCmec.
  
  
  CONCLUSIONS
  Our results imply that CA-MRSA origin, epidemiology and population structure in Europe is very dissimilar from that of USA.
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Rolo
authors.forename: Maria
authors.initials: M
authors.lastname: Miragaia
authors.forename: Agata
authors.initials: A
authors.lastname: Turlej-Rogacka
authors.forename: Joanna
authors.initials: J
authors.lastname: Empel
authors.forename: Ons
authors.initials: O
authors.lastname: Bouchami
authors.forename: Nuno A
authors.initials: NA
authors.lastname: Faria
authors.forename: Ana
authors.initials: A
authors.lastname: Tavares
authors.forename: Waleria
authors.initials: W
authors.lastname: Hryniewicz
authors.forename: Ad C
authors.initials: AC
authors.lastname: Fluit
authors.forename: Hermínia
authors.initials: H
authors.lastname: de Lencastre
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005060:Europe / Q000453:epidemiology; D005260:Female; D014644:Genetic Variation; D005828:Genetics, Population; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics*