title: Assessment of virulence diversity of methicillin-resistant Staphylococcus aureus strains with a Drosophila melanogaster infection model.
abstract: BACKGROUND
  Staphylococcus aureus strains with distinct genetic backgrounds have shown different virulence in animal models as well as associations with different clinical outcomes, such as causing infection in the hospital or the community. With S. aureus strains carrying diverse genetic backgrounds that have been demonstrated by gene typing and genomic sequences, it is difficult to compare these strains using mammalian models. Invertebrate host models provide a useful alternative approach for studying bacterial pathogenesis in mammals since they have conserved innate immune systems of biological defense. Here, we employed Drosophila melanogaster as a host model for studying the virulence of S. aureus strains.
  
  
  RESULTS
  Community-associated methicillin-resistant S. aureus (CA-MRSA) strains USA300, USA400 and CMRSA2 were more virulent than a hospital-associated (HA)-MRSA strain (CMRSA6) and a colonization strain (M92) in the D. melanogaster model. These results correlate with bacterial virulence in the Caenorhabditis elegans host model as well as human clinical data. Moreover, MRSA killing activities in the D. melanogaster model are associated with bacterial replication within the flies. Different MRSA strains induced similar host responses in D. melanogaster, but demonstrated differential expression of common bacterial virulence factors, which may account for the different killing activities in the model. In addition, hemolysin α, an important virulence factor produced by S. aureus in human infections is postulated to play a role in the fly killing.
  
  
  CONCLUSIONS
  Our results demonstrate that the D. melanogaster model is potentially useful for studying S. aureus pathogenicity. Different MRSA strains demonstrated diverse virulence in the D. melanogaster model, which may be the result of differing expression of bacterial virulence factors in vivo.
authors.affiliation: Department of Pathology & Laboratory Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada.
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Wu
authors.forename: John
authors.initials: J
authors.lastname: Conly
authors.forename: Michael
authors.initials: M
authors.lastname: Surette
authors.forename: Christopher
authors.initials: C
authors.lastname: Sibley
authors.forename: Sameer
authors.initials: S
authors.lastname: Elsayed
authors.forename: Kunyan
authors.initials: K
authors.lastname: Zhang
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000382:microbiology; D004195:Disease Models, Animal; D004331:Drosophila melanogaster / Q000382:microbiology*; D015870:Gene Expression; D014644:Genetic Variation; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000472:pathogenicity*; D013203:Staphylococcal Infections / Q000382:microbiology / Q000473:pathology; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: D037521:Virulence Factors