Use of Procalcitonin as a Tool to Enhance Antimicrobial Stewardship

Advances in rapid diagnostic methods have significantly enhanced the management of community-acquired pneumonia (CAP). Molecular testing methods have brought forth new potential for identification of respiratory pathogens. Additionally, studies have suggested that the biomarker procalcitonin (PCT), can help to distinguish between bacterial and viral etiologies, reduce antibacterial use, and can predict severity of infection. In this issue, Deshpande et al, in a multihospital observational study, demonstrated that PCT testing in non-intensive care unit patients admitted with CAP was associated with modest but significant reduction in antibiotic duration [1]. This finding adds support for use of PCT to enhance optimal antimicrobial stewardship. PCT is a peptide precursor of calcitonin that is released by parenchymal cells in response to certain bacterial-specific proinflammatory mediators (ie, interleukin 1, tumor necrosis factor-alpha, and interleukin-6) leading to elevated serum levels in patients with bacterial infections [2, 3]. In contrast, PCT is downregulated in patients with viral infections because of the release of cytokines typically associated with viral infections (eg, interferon-gamma). PCT shows a prompt increase upon initial infection within 6–12 hours and a rapid reduction when the bacterial infection is controlled by the host immune system and antimicrobial therapy. The kinetics of PCT production closely mirror the course of a bacterial infection, making it an effective tool to support initiation and deescalation of antibiotic treatment. Because of these characteristics, PCT can provide helpful information regarding the decision for use of or discontinuation of antibacterial agents.