Biomarkers of inflammation in respiratory tract infections: a narrative review

Biomarkers of inflammation in respiratory tract infections

Abstract

Background and purpose: Respiratory tract infections (RTIs) are a global public health issue and one of the major causes of morbidity and mortality worldwide, especially in immune sensitive or compromised population. It is particularly challenging to distinguish viral from bacterial RTI based only on the symptoms presentations. Bacterial cultures are the gold standard in detecting the causative pathogens. However, they have several shortcomings such as variable diagnostic sensitivity, a relatively long turnaround time and the fact that not all possible pathogens can be detected using one culture. In such case, tests detecting host-response blood-based biomarkers are a valuable contribution in diagnosis making and patient management.

Materials and methods: A literature search was conducted in the PubMed electronic database from January 1st 2005 to March 31st 2025 using the following search terms “Clinical Laboratory Techniques” AND “Serum” AND “Infections” AND “Respiratory tract diseases” AND “Diagnosis” AND “Prognosis”. Randomized,non-randomized studies as well as reviews were taken into consideration.

Results: C-reactive protein and procalcitonin are at the present the most robust and widely used biomarkers; however newer biomarkers such as serum calprotectin, pentraxin 3 and presepsin, as well as combinations of different biomarkers with high potential for clinical utility are emerging.

Conclusions: Host-response biomarkers of inflammation are useful tools in RTIs management when used together in conjunction with clinical symptoms. Depending on the kinetics of their release into the circulation and their elimination, they can be used as either early markers of inflammation or as a prognostic marker for disease severity and mortality.