Molecular Characterization of Endocarditis-Associated Staphylococcus aureus

ABSTRACTInfective endocarditis (IE) is a life-threatening infection of the heart endothelium and valves. Staphylococcus aureusis a predominant cause of severe IE and is frequently associated with infections in health care settings and device-related infections. Multilocus sequence typing (MLST), spatyping, and virulence gene microarrays are frequently used to classify S. aureusclinical isolates. This study examined the utility of these typing tools to investigate S. aureusepidemiology associated with IE. Ninety-seven S. aureusisolates were collected from patients diagnosed with (i) IE, (ii) bloodstream infection related to medical devices, (iii) bloodstream infection not related to medical devices, and (iv) skin or soft-tissue infections. The MLST clonal complex (CC) for each isolate was determined and compared to the CCs of members of the S. aureuspopulation by eBURST analysis. The spatype of all isolates was also determined. A null model was used to determine correlations of IE with CC and spatype. DNA microarray analysis was performed, and a permutational analysis of multivariate variance (PERMANOVA) and principal coordinates analysis were conducted to identify genotypic differences between IE and non-IE strains. CC12, CC20, and spatype t160 were significantly associated with IE S. aureus. A subset of virulence-associated genes and alleles, including genes encoding staphylococcal superantigen-like proteins, fibrinogen-binding protein, and a leukocidin subunit, also significantly correlated with IE isolates. MLST, spatyping, and microarray analysis are promising tools for monitoring S. aureusepidemiology associated with IE. Further research to determine a role for the S. aureusIE-associated virulence genes identified in this study is warranted.