Bacteriemia/endocarditis

F. Vandenesch, PU-PH in close collaboration with P. Verhoeven PU-PH-GIMAP

Staphylococcus aureus bacteremia represents a major public health issue due to its high incidence and mortality rate. Through various approaches, the team investigates links between strain characteristics and the severity of bacteremia in order to better understand the pathophysiology of these systemic infections. 

Clinical studies have shown, on one hand, that certain inflammatory markers may be positively or negatively correlated with poor patient outcomes. In parallel, numerous in vitro and in vivo studies have focused on the interactions between S. aureus and the cellular/humoral effectors of the blood, in order to better understand how this pathogen survives in the bloodstream and evades elimination by the immune system. However, the connection between these two fields of research remains poorly documented, and we therefore still do not know how the characteristics of clinical S. aureus strains and their interaction with circulating immune components contribute to the severity of these infections. 

• Axis 1 - Targeted proteomics

Different cohorts of patients with bacteremia (past or ongoing) have made it possible to collect extensive clinical data and to isolate and preserve dozens of strains responsible for these infections. Through a targeted proteomics study, the expression levels of 41 bacterial factors have been quantified in these isolates. The clinical severity data can then be linked to the protein expression profiles to determine whether patient prognosis may be influenced and predicted by the synthesis levels of specific bacterial factors. (contact : françois.vandenesch@univ-lyon1.fr)

• Axis 2 - Phenotypic characterization

Building on the same cohorts of patients with S. aureus bacteremia, this axis aims to characterize numerous clinical strains through various phenotypic tests relevant to bloodstream infections. Among other aspects, the ability of isolates to survive and induce an inflammatory response in human blood, as well as their virulence in in vivo infection models, is evaluated. Strain behavior is then correlated with clinical data, allowing assessment of whether certain bacterial characteristics may influence the severity of bacteremia. (contact : stephane.pont@univ-lyon1.fr / françois.vandenesch@univ-lyon1.fr)