Septic shock is defined as a subset of sepsis with severe metabolism alterations, leading to organ failure. Septic shock is associated with a high mortality, around 40% according to the SEPSIS 3 definition. Metabolic alterations are responsible for lactic acidosis, and results in mitochondrial dysfunction. This study aims at evaluate the impact of exogenous metabolites on restoring mitochondrial function in septic shock patients with lactate acidosis. Mitochondrial metabolism (quantitative analysis, mitochondrial function) in intact Peripheral Blood Mononuclear Cells (PBMC) will be isolate and analyse from patients at the early phase of septic shock (admission), at day 2 and 4. Participant's medical history will be recorded: renal and liver metabolism, severity scores and outcomes and the need for supportive care in the intensive care unit (ICU) until 28 days after admission. Furthermore, the investigators will evaluate wether selected metabolites added to the cell culture medium may improve mitochondrial metabolism.