Figure 1

Use of C-reactive protein and procalcitonin to guide antimicrobial therapy in critically ill patients. C-reactive protein (CRP) was tested only in a single center trial with predominantly medical ICU patients. This flowchart does not apply to immune-compromised patients (for example, febrile neutropenia) or to patients with infections requiring long-term antibiotic therapy (for example, infectious endocarditis, cerebral abscess, bacteremia due to Staphylococcus aureus). ^£Most trials investigating procalcitonin (PCT)-guided protocols tested the role of this marker in guiding the decision of antibiotic interruption. Initiating antibiotics for all critically ill patients with suspected infection is probably the safest decision, regardless the levels of laboratory biomarkers. However, this decision must be reassessed daily. PCT and CRP are proposed as additional tools to diagnose infection, and different cutoff levels have been proposed in the literature. ^¶Consider stopping antibiotics before day 7 in patients with no proven infection (for example, negative cultures) regardless the levels of CRP or PCT. SOFA, Sequential Organ Failure Assessment.