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

Area of Science:

• Infectious Diseases
• Microbiology
• Genetics

Background:

• Infective endocarditis (IE) is a severe complication of Staphylococcus aureus bacteremia.
• Host factors for IE are known, but bacterial determinants remain unclear.

Purpose of the Study:

• To identify distinct genetic features differentiating Staphylococcus aureus isolates causing IE versus bacteremia.
• To explore the role of bacterial characteristics in IE pathogenesis.

Main Methods:

• Prospective collection of S. aureus isolates from definite IE and bacteremia cases.
• Phenotypic characterization of isolates.
• Genotypic profiling using microarray analysis and Discriminant Analysis of Principal Components (DAPC).

Main Results:

• Univariate analyses showed no significant differences between IE and bacteremia isolates.
• Multivariate DAPC analysis of microarray data successfully segregated IE and bacteremia isolates (80.6% correct reassignment).
• A discriminant function based on 8 genetic markers showed high performance in validation cohorts (up to 86.1%).

Conclusions:

• Community-acquired S. aureus isolates causing IE are genetically distinct from bacteremia isolates.
• Subtle combinations of genetic markers can differentiate these isolate types.
• Bacterial genetic factors likely contribute to the development of IE in S. aureus bacteremia.