Molecular Biomarkers for Sepsis

Inclusion Criteria: * Admission to the ICU of one of the participating centers. * Cases: severe community acquired pneumonia with requirement for ICU admission. * Controls: Clinical phenotype of inflammation not due to suspected sepsis In addition, control patients will be patients with fever \>38°C, CRP \>100mg/L, no infection focus expected in ≥ 24h. * All required sample types can most likely be collected within the first 24h visits. * Expected ICU stay of more than 24h. Exclusion Criteria: * Admission to the hospital within the prior 14 days. * Patients with psychosis * Evidence of a hospital acquired pneumonia. * One of the following respiratory conditions: Acute exacerbation of chronic obstructive pulmonary disease (COPD) or bronchiectasis, acute severe asthma, aspiration pneumonia, tuberculosis, clinical suspected viral pneumonia without bacterial infection, cardiogenic pulmonary oedema. * Patients with an acute respiratory distress Syndrome (ARDS). * Patient which can be managed as outpatients and do not require an ICU. * Patient where a transmission to another institution is likely within the next 24h. * Documented rejection of the general consent or participation to research in general. * Patients with a palliative situation and a life expectancy due to other diseases (e.g. progressed cancer) less than 28 days.