Assessing the Procalcitonin-guidance and Molecular-guided Diagnosis for Therapy of Severe Infections (the MODIFY Trial)

Inclusion Criteria: * Male or female * For women of child-bearing potential, willingness to avoid pregnancy during the study and agreement to notify investigator if pregnancy occurs. * Age more than or equal to 18 years * Patients who have completed their participation in another study for more than 30 days can be included in this study. * Written informed consent provided by the patient or by their legal representative in case of patients unable to consent due to sepsis onset affecting their mental capacity. * Sepsis defined by the Sepsis-3 definition; this is defined separately for community-acquired sepsis and for hospital-acquired sepsis. Community-acquired sepsis is defined as any SOFA score 2 points or more for patients admitted in hospital emergencies with community-acquired pneumonia (CAP), community-acquired acute pyelonephritis (AP) or community-acquired primary bacteremia (BSI). CAP, AP and BSI are considered community-acquired for patients who have no history of hospitalization lasting more than 2 days the last 90 days or who are not under hemodialysis or who are not residents of long-term care facilities. Hospital-acquired sepsis is defined as any SOFA score increase by 2 points or more from the admission SOFA score for patients with onset of hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), acute pyelonephritis (AP) or primary bacteremia (BSI) at least 48 hours after hospital admission. For patients with history of hospitalization lasting more than 2 days the last 90 days or who are under hemodialysis or who are residents of long-term care facilities and are admitted to hospital with HAP, VAP, AP and BSI the definition of hospital-acquired sepsis applies. In this case, the baseline SOFA score is considered as the known SOFA score before infection onset. * Presence of one of the following infections: community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), acute pyelonephritis (AP) and primary bacteremia (BSI). * Positive blood culture Exclusion Criteria: * Failure to obtain written consent to participate * Previous enrollment in this study within the past 90 days. Patients enrolled in another study will not be accepted. * Patients in pregnancy or breastfeeding. Women of child-bearing potential will be screened by a urine pregnancy test before inclusion in the study * Patients receiving prolonged antibiotic therapies (e.g. endocarditis, implantable device-associated infection, cerebral/hepatic abscess, osteomyelitis, meningitis) * Patients with severe infections due to viruses or parasites (e.g. Dengue, Toxoplasma gondii, Plasmodium spp.) * Patients with infection due to Mycobacterium tuberculosis. * Patients suffering from cystic fibrosis * Severely immunocompromised patients such as a) patients with infection by the human immunodeficiency virus and with a CD4 count of less than 200 cells/mm3; b) neutropenic patients with less than 500 neutrophils/mm3; and c) patients with solid organ transplantation.