Procalcitonin and the role of biomarkers in the diagnosis and management of sepsis.

Sepsis and severe sepsis cause significant morbidity and mortality among populations worldwide; the rapid diagnosis poses a considerable challenge to physicians in acute care settings. An ideal biomarker should allow, with high diagnostic accuracy, for an early and rapid recognition of sepsis. Procalcitonin (PCT) is a recently rediscovered biomarker that fulfills many of these requirements, especially in comparison to "older" and commonly used biomarkers, and that has demonstrated superior diagnostic accuracy for a variety of infections, including sepsis. While blood cultures are still considered the "gold standard" for the diagnosis of bacteremia and sepsis, and are perhaps one of the most important functions of the clinical microbiology laboratory, PCT provides important information in early stages of sepsis as well as during antimicrobial treatment. In fact, PCT can be useful for antimicrobial stewardship and its utilization may safely lead to significant reduction of unnecessary antimicrobial therapy. However, PCT is also less than a universal and perfect biomarker, as it can also be increased in noninfectious disease conditions. Laboratories and clinicians must appreciate the complexity of diagnostic algorithms for sepsis and understand the particular information that biomarkers, such as PCT, can offer. In that context, it is necessary to not only recognize the importance of critical clinical awareness and thorough physical patient examination, but also to understand traditional microbiological methods and the need for highly sensitive biomarker assays in order to facilitate an early diagnosis and goal-directed therapy in patients suspected of sepsis. This review is intended to provide additional information for clinicians and microbiologists to better understand the physiology and diagnostic utility of procalcitonin for sepsis and other infectious disease conditions.