title: Differential arthritogenicity of Staphylococcus aureus strains isolated from biological samples.
abstract: BACKGROUND
  Staphylococcus aureus is the most common agent of septic arthritis that is a severe, rapidly progressive and destructive joint disease. Superantigens produced by S. aureus are considered the major arthritogenic factors. In this study, we compared the arthritogenic potential of five superantigen-producing staphylococcal strains.
  
  
  METHODS
  Male C57BL/6 mice were intravenously infected with ATCC 19095 SEC+, N315 ST5 TSST-1+, S-70 TSST-1+, ATCC 51650 TSST-1+ and ATCC 13565 SEA+ strains. Clinical parameters as body weight, arthritis incidence and clinical score were daily evaluated. Joint histopathological analysis and spleen cytokine production were evaluated at the 14th day after infection.
  
  
  RESULTS
  Weight loss was observed in all infected mice. ATCC 19095 SEC+, N315 ST5 TSST-1+ and S-70 TSST-1+ were arthritogenic, being the highest scores observed in ATCC 19095 SEC+ infected mice. Intermediate and lower clinical scores were observed in N315 ST5 TSST-1+ and S-70 TSST-1+ infected mice, respectively. The ATCC 13565 SEA+ strain caused death of 85% of the animals after 48 h. Arthritis triggered by the ATCC 19095 SEC+ strain was characterized by accentuated synovial hyperplasia, inflammation, pannus formation, cartilage destruction and bone erosion. Similar joint alterations were found in N315 ST5 TSST-1+ infected mice, however they were strikingly more discrete. Only minor synovial proliferation and inflammation were triggered by the S-70 TSST-1+ strain. The lowest levels of TNF-α, IL-6 and IL-17 production in response to S. aureus stimulation were found in cultures from mice infected with the less arthritogenic strains (S-70 TSST-1+ and ATCC 51650 TSST-1+). The highest production of IL-17 was detected in mice infected with the most arthritogenic strains (ATCC 19095 SEC+ and N315 ST5 TSST-1+).
  
  
  CONCLUSIONS
  Together these results demonstrated that S. aureus strains, isolated from biological samples, were able to induce a typical septic arthritis in mice. These results also suggest that the variable arthritogenicity of these strains was, at least in part, related to their differential ability to induce IL-17 production.
authors.affiliation: Department of Microbiology and Immunology, Biosciences Institute, Univ, Estadual Paulista (UNESP), Distrito de Rubião Júnior s/n, 18618-070 Botucatu, São Paulo, Brazil. sartori@ibb.unesp.br.
authors.forename: Priscila Maria
authors.initials: PM
authors.lastname: Colavite-Machado
authors.forename: Larissa Lumi Watanabe
authors.initials: LL
authors.lastname: Ishikawa
authors.forename: Thaís Graziela Donegá
authors.initials: TG
authors.lastname: França
authors.forename: Sofia Fernanda Gonçalves
authors.initials: SF
authors.lastname: Zorzella-Pezavento
authors.forename: Larissa Camargo
authors.initials: LC
authors.lastname: da Rosa
authors.forename: Fernanda
authors.initials: F
authors.lastname: Chiuso-Minicucci
authors.forename: Maria de Lourdes Ribeiro de Souza
authors.initials: Mde L
authors.lastname: da Cunha
authors.forename: Gustavo Pompermaier
authors.initials: GP
authors.lastname: Garlet
authors.forename: Alexandrina
authors.initials: A
authors.lastname: Sartori
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology; D001170:Arthritis, Infectious / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D020381:Interleukin-17 / Q000276:immunology; D015850:Interleukin-6 / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000276:immunology* / Q000302:isolation & purification; D018089:Superantigens / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D020381:Interleukin-17; D015850:Interleukin-6; D018089:Superantigens