title: Impact of sarA and Phenol-Soluble Modulins on the Pathogenesis of Osteomyelitis in Diverse Clinical Isolates of Staphylococcus aureus.
abstract: We used a murine model of acute, posttraumatic osteomyelitis to evaluate the virulence of two divergent Staphylococcus aureus clinical isolates (the USA300 strain LAC and the USA200 strain UAMS-1) and their isogenic sarA mutants. The results confirmed that both strains caused comparable degrees of osteolysis and reactive new bone formation in the acute phase of osteomyelitis. Conditioned medium (CM) from stationary-phase cultures of both strains was cytotoxic to cells of established cell lines (MC3TC-E1 and RAW 264.7 cells), primary murine calvarial osteoblasts, and bone marrow-derived osteoclasts. Both the cytotoxicity of CM and the reactive changes in bone were significantly reduced in the isogenic sarA mutants. These results confirm that sarA is required for the production and/or accumulation of extracellular virulence factors that limit osteoblast and osteoclast viability and that thereby promote bone destruction and reactive bone formation during the acute phase of S. aureus osteomyelitis. Proteomic analysis confirmed the reduced accumulation of multiple extracellular proteins in the LAC and UAMS-1 sarA mutants. Included among these were the alpha class of phenol-soluble modulins (PSMs), which were previously implicated as important determinants of osteoblast cytotoxicity and bone destruction and repair processes in osteomyelitis. Mutation of the corresponding operon reduced the cytotoxicity of CM from both UAMS-1 and LAC cultures for osteoblasts and osteoclasts. It also significantly reduced both reactive bone formation and cortical bone destruction by CM from LAC cultures. However, this was not true for CM from cultures of a UAMS-1 psmα mutant, thereby suggesting the involvement of additional virulence factors in such strains that remain to be identified.
authors.affiliation: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Allister J
authors.initials: AJ
authors.lastname: Loughran
authors.affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Dana
authors.initials: D
authors.lastname: Gaddy
authors.affiliation: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Beenken
authors.affiliation: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Meeker
authors.affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Roy
authors.initials: R
authors.lastname: Morello
authors.affiliation: Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Biochemistry, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Stephanie D
authors.initials: SD
authors.lastname: Byrum
authors.affiliation: Department of Biochemistry, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Tackett
authors.affiliation: Department of Pediatrics and Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Cassat
authors.affiliation: Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA smeltzermarks@uams.edu.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Smeltzer
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation / Q000235:genetics; D009876:Operon / Q000235:genetics; D010006:Osteoblasts / Q000382:microbiology / Q000473:pathology; D010010:Osteoclasts / Q000382:microbiology / Q000473:pathology; D010019:Osteomyelitis / Q000382:microbiology* / Q000473:pathology*; D040901:Proteomics / Q000379:methods; D013203:Staphylococcal Infections / Q000382:microbiology / Q000473:pathology; D013211:Staphylococcus aureus / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C492107:SarA protein, Staphylococcus aureus; D037521:Virulence Factors