PROBIC

Rationale: Procalcitonin measurements can reduce the number of blood cultures in the ICU.

Objective: The investigators suggest that PCT is a marker for blood stream infection in all patients in the ICU in whom attending physicians/ intensivists order blood culturing in the suspicion of microbial infection. The investigators want to demonstrate that its use for guiding blood culturing is cost-effective and safe compared with blood cultures alone.

Study design: Prospective, non- inferiority, multicenter, single-blinded, cluster- randomised cross-over clinical trial.

Intervention (if applicable): The intensive care units will be allocated into two groups: a control group (blood culture) and the intervention group (procalcitonin).

Main study parameters/endpoints: Safety, expressed as mortality at day 28 and 90, with a mortality difference not exceeding a between groups difference of 10% by non-inferiority analysis.

Cost-effectiveness, expressed in euro, calculated by deducting costs of procalcitonin testing from saved blood cultures compared with standard treatment spending on blood cultures in the control group.

ICIS

Rationale: The aim was to evaluate the Intensive Care Infection Score (ICIS) in predicting microbial infection and its sequelae in critically ill patients in whom attending physicians/ intensivists order blood culturing in the suspicion of microbial infection.

Objective: Because of the complexity of the pathophysiology of systemic inflammation it is unlikely that a single parameter will have sufficient diagnostic accuracy for infection. Therefore we will study combining parameters producing a diagnostic score.

Study design: Prospective, multicenter, cohort trial. Supplement for the control arm of the ProBIC study.

Intervention (if applicable): Blood is drawn for daily routine laboratory measurements and collected in K3EDTA aliqnots. The ICIS score is composed of five blood-cell derived parameters which can be extracted using the same aliqnots.

Main study parameters/endpoints: To develop and evaluate a blood- cell derived score to enable the diagnosis of microbial infection, its likelihood, its invasiveness and severity.

Inclusion Criteria:

• Patients will need to be over the age of 18 and suffering from an assumed infection deemed clinically worthy for blood culturing.

Exclusion Criteria:

• Uncontrolled malignancy
• Immunosuppressive or immunostimulatory therapy
• Neutropenia, defined as leukocyte count less then 0.5x109/L
• Moribund patients
• Predetermined illness with an expected death within 24 hours