Staphylococcus aureus infective endocarditis versus bacteremia strains: Subtle genetic differences at stake.

Abstract

Infective endocarditis (IE)((1)) is a severe condition complicating 10-25% of Staphylococcus aureus bacteremia. Although host-related IE risk factors have been identified, the involvement of bacterial features in IE complication is still unclear. We characterized strictly defined IE and bacteremia isolates and searched for discriminant features. S. aureus isolates causing community-acquired, definite native-valve IE (n=72) and bacteremia (n=54) were collected prospectively as part of a French multicenter cohort. Phenotypic traits previously reported or hypothesized to be involved in staphylococcal IE pathogenesis were tested. In parallel, the genotypic profiles of all isolates, obtained by microarray, were analyzed by discriminant analysis of principal components (DAPC)((2)). No significant difference was observed between IE and bacteremia strains, regarding either phenotypic or genotypic univariate analyses. However, the multivariate statistical tool DAPC, applied on microarray data, segregated IE and bacteremia isolates: IE isolates were correctly reassigned as such in 80.6% of the cases (C-statistic 0.83, P<0.001). The performance of this model was confirmed with an independent French collection IE and bacteremia isolates (78.8% reassignment, C-statistic 0.65, P<0.01). Finally, a simple linear discriminant function based on a subset of 8 genetic markers retained valuable performance both in study collection (86.1%, P<0.001) and in the independent validation collection (81.8%, P<0.01). We here show that community-acquired IE and bacteremia S. aureus isolates are genetically distinct based on subtle combinations of genetic markers. This finding provides the proof of concept that bacterial characteristics may contribute to the occurrence of IE in patients with S. aureus bacteremia.

• Authors: Coralie Bouchiat, Karen Moreau, Sébastien Devillard, Jean-Philippe Rasigade, Amandine Mosnier, Tom Geissmann, Michèle Bes, Anne Tristan, Gérard Lina, Frédéric Laurent, Lionel Piroth, Nejla Aissa, Xavier Duval, Vincent Le Moing, François Vandenesch, French VIRSTA Study Group
• Journal: Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases (Infect Genet Evol) Vol. 36 Pg. 524-530 (Dec 2015) ISSN: 1567-7257 [Electronic] Netherlands
• PMID: 26318542 (Publication Type: Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015. Published by Elsevier B.V.

Chemical References

• Genetic Markers

Topics

• Bacteremia (microbiology)
• Community-Acquired Infections
• Endocarditis, Bacterial (microbiology)
• Genes, Bacterial
• Genetic Markers
• Genetic Variation
• Genotype
• Humans
• Phenotype
• Reproducibility of Results
• Staphylococcal Infections (microbiology)
• Staphylococcus aureus (classification, genetics, isolation & purification)