title: Evolutionary Origin of the Staphylococcal Cassette Chromosomemec(SCCmec).
abstract: Several lines of evidence indicate that the most primitive staphylococcal species, those of theStaphylococcus sciurigroup, were involved in the first stages of evolution of the staphylococcal cassette chromosomemec(SCCmec), the genetic element carrying the β-lactam resistance genemecAHowever, many steps are still missing from this evolutionary history. In particular, it is not known howmecAwas incorporated into the mobile element SCC prior to dissemination amongStaphylococcus aureusand other pathogenic staphylococcal species. To gain insights into the possible contribution of several species of theStaphylococcus sciurigroup to the assembly of SCCmec, we sequenced the genomes of 106 isolates, comprisingS. sciuri(n= 76),Staphylococcus vitulinus(n= 18), andStaphylococcus fleurettii(n= 12) from animal and human sources, and characterized the native location ofmecAand the SCC insertion site by using a variety of comparative genomic approaches. Moreover, we performed a single nucleotide polymorphism (SNP) analysis of the genomes in order to understand SCCmecevolution in relation to phylogeny. We found that each of three species of theS. sciurigroup contributed to the evolution of SCCmec:S. vitulinusandS. fleurettiicontributed to the assembly of themeccomplex, andS. sciurimost likely provided the mobile element in whichmecAwas later incorporated. We hypothesize that an ancestral SCCmecIII cassette (an element carried by one of the most epidemic methicillin-resistantS. aureusclones) originated inS. sciuripossibly by a recombination event in a human host or a human-created environment and later was transferred toS. aureus.
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.|Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Rolo
authors.affiliation: MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.
authors.forename: Peder
authors.initials: P
authors.lastname: Worning
authors.affiliation: MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.
authors.forename: Jesper Boye
authors.initials: JB
authors.lastname: Nielsen
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Rory
authors.initials: R
authors.lastname: Bowden
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.|Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Ons
authors.initials: O
authors.lastname: Bouchami
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Damborg
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.|Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St. Kitts, West Indies.
authors.forename: Luca
authors.initials: L
authors.lastname: Guardabassi
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Vincent
authors.identifier: 0000-0001-5722-9445
authors.initials: V
authors.lastname: Perreten
authors.affiliation: Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tomasz
authors.affiliation: MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Westh
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.|Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, USA.
authors.forename: Hermínia
authors.initials: H
authors.lastname: de Lencastre
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal miragaia@itqb.unl.pt.|Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Maria
authors.initials: M
authors.lastname: Miragaia
mesh_terms: D002876:Chromosomes, Bacterial / Q000235:genetics*; D019143:Evolution, Molecular; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D013210:Staphylococcus / Q000187:drug effects / Q000235:genetics; D018440:beta-Lactam Resistance / Q000235:genetics
keywords: SCCmec; beta-lactam resistance; evolution; mecA; staphylococci