[Diagnostic Approaches in Sepsis - Part 1: General Diagnostic Principles, Focus Identification and Source Control]

Sepsis and septic shock represent medical emergencies with persistently high mortality rates. According to the lately revised Surviving Sepsis Campaign (SSC) guidelines, focus identification/pathogen detection and the initial administration of broad-spectrum antibiotics are to be secluded within one hour after recognition of the symptoms of sepsis. However, there is dispute concerning the so called hour-1 bundle. Being a core aspect of focus identification, imaging modalities mainly depend on the suspected site of infection and the individual patient. Contrast agent-enhanced computed tomography (CT) is the modality usually used in critically ill patients. The microbiological pathogen detection still largely remains culture-based. This emphasizes the significance of microbiological specimen obtained from easily accessible body compartments and at least 2 blood culture sets. If possible, blood cultures should be drawn prior to antibiotic administration. Intraoperatively obtained swabs of otherwise sterile body compartments are of utmost importance with regard to microbiological pathogen detection. Catheters and implanted medical devices (i.e. cardiac pacemakers or defibrillators) suspicious of infection should be explanted and sent in for microbiological workup as soon as possible. All necessary source control measures should be realized as soon as medically possible but at least within 6 - (12) hours after the onset of symptoms. There is no specific biomarker for sepsis so far. Procalcitonin (PCT) and C-reactive protein (CRP) are crucial biomarkers in terms of infectious disease management and guidance of antimicrobial therapy in the ICU. Positive clinical trials showed that biomarkers like the midregional pro-adrenomedullin (MR-proADM) or presepsin might be promising candidates in the diagnosis of sepsis in the future. As an important marker of microcirculatory failure and disrupted cell metabolism, lactate serum concentrations (and lactate-clearance, respectively) are of prognostic value in septic patients.