title: Molecular characterization of methicillin-resistant Panton-valentine leukocidin positive staphylococcus aureus clones disseminating in Tunisian hospitals and in the community.
abstract: BACKGROUND
  The spread of MRSA strains at hospitals as well as in the community are of great concern worldwide. We characterized the MRSA clones isolated at Tunisian hospitals and in the community by comparing them to those isolated in other countries.
  
  
  RESULTS
  We characterized 69 MRSA strains isolated from two Tunisian university hospitals between the years 2004-2008. Twenty-two of 28 (79%) community-associated MRSA (CA-MRSA) strains and 21 of 41 (51%) healthcare-associated MRSA (HA-MRSA) strains were PVL-positive. The PVL-positive strains belonged to predicted founder group (FG) 80 in MLST and carried either type IVc SCCmec or nontypeable SCCmec that harbours the class B mec gene complex. In contrast, very diverse clones were identified in PVL-negative strains: three FGs (5, 15, and 22) for HA-MRSA strains and four FGs (5, 15, 45, and 80) for CA-MRSA strains; and these strains carried the SCCmec element of either type I, III, IVc or was nontypeable. The nucleotide sequencing of phi7401PVL lysogenized in a CA-MRSA strain JCSC7401, revealed that the phage was highly homologous to phiSA2mw, with nucleotide identities of more than 95%. Furthermore, all PVL positive strains were found to carry the same PVL phage, since these strains were positive in two PCR studies, identifying gene linkage between lukS and mtp (major tail protein) and the lysogeny region, both of which are in common with phi7401PVL and phiSa2mw.
  
  
  CONCLUSIONS
  Our experiments suggest that FG80 S. aureus strains have changed to be more virulent by acquiring phi7401PVL, and to be resistant to β-lactams by acquiring SCCmec elements. These novel clones might have disseminated in the Tunisian community as well as at the Tunisian hospitals by taking over existing MRSA clones.
authors.affiliation: Department of Infection Control Science, Juntendo University, Tokyo, Japan.
authors.forename: Ben Jomàa-Jemili
authors.initials: BJ
authors.lastname: Mariem
authors.forename: Teruyo
authors.initials: T
authors.lastname: Ito
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Jingxun
authors.initials: J
authors.lastname: Jin
authors.forename: Shanshuang
authors.initials: S
authors.lastname: Li
authors.forename: Boutiba-Ben Boubaker
authors.initials: BB
authors.lastname: Ilhem
authors.forename: Hammami
authors.initials: H
authors.lastname: Adnan
authors.forename: Xiao
authors.initials: X
authors.lastname: Han
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramatsu
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics*; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005098:Exotoxins / Q000235:genetics*; D005838:Genotype; D006785:Hospitals, University; D006801:Humans; D007956:Leukocidins / Q000235:genetics*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D039002:Prophages / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D014416:Tunisia / Q000453:epidemiology; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics; D018440:beta-Lactam Resistance
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D037521:Virulence Factors