Role of Procalcitonin in Respiratory Infections.

BACKGROUND: Respiratory infections remain a leading cause of morbidity and mortality worldwide, encompassing a broad spectrum of conditions ranging from mild upper respiratory tract infections to severe pneumonia and sepsis. One of the major clinical challenges in their management is differentiating bacterial from viral infections, which has direct implications for appropriate antibiotic use. Overuse and misuse of antibiotics contribute significantly to antimicrobial resistance, making the identification of reliable biomarkers increasingly important. Procalcitonin has emerged as a promising biomarker that aids in the diagnosis and management of respiratory infections by reflecting systemic bacterial infection and inflammatory response.

OBJECTIVE: To review the role of procalcitonin in the diagnosis, prognosis, and antibiotic stewardship of respiratory infections.

METHODOLOGY: A narrative review was conducted using literature from electronic databases including PubMed, Scopus, and Google Scholar. Relevant studies published in English were identified using keywords such as "procalcitonin," "respiratory infections," "pneumonia," "sepsis," and "antibiotic stewardship." Clinical trials, observational studies, guidelines, and review articles focusing on the clinical utility of procalcitonin were included. Studies lacking clinical relevance or focusing on nonrespiratory conditions were excluded.

FINDINGS: Procalcitonin is a sensitive biomarker that rises in response to bacterial infections and remains low in viral infections and noninfectious inflammatory states. It has demonstrated significant utility in differentiating bacterial from viral respiratory infections, guiding initiation and discontinuation of antibiotic therapy, and reducing unnecessary antibiotic exposure. In conditions such as community-acquired pneumonia, acute exacerbations of chronic obstructive pulmonary disease, and sepsis, procalcitonin-guided strategies have been associated with improved antibiotic stewardship without compromising patient outcomes. In addition, procalcitonin levels may have prognostic value, correlating with disease severity and risk of complications. However, factors such as cost, availability, and variability in cutoff values may influence its routine clinical use.

CONCLUSION: Procalcitonin is a valuable biomarker in the management of respiratory infections, particularly in guiding antibiotic therapy and improving clinical decision-making. Its integration into clinical protocols can enhance diagnostic accuracy and support antimicrobial stewardship efforts. Further standardization and wider accessibility are needed to optimize its use across diverse healthcare settings.