Evaluation of potential biomarkers for the discrimination of bacterial and viral infections

Purpose Timely knowledge of the bacterial etiology and localization of infection are important for empirical antibiotic therapy. Thus, the goal of this study was to evaluate routinely used biomarkers together with novel laboratory parameters in the diagnosis of infection. Methods In this prospective study, 54 adult patients with bacterial infections admitted to the Department of Infectious Diseases were included. For comparison, 27 patients with viral infections were enrolled. In these patients, white blood cell (WBC) counts, differential blood counts, serum levels of procalcitonin (PCT), IL-1 beta, IL-6, IL-8, IL-10, IL-12, TNF-alpha, IFN-gamma, soluble CD14 (sCD14), heparin-binding protein (HBP), cortisol (Cort), and monocyte surface expression of TLR2, TLR4, HLA-DR, and CD14 were analyzed. Also, these biomarkers were evaluated in 21 patients with acute community-acquired bacterial pneumonia (CABP), as well as in 21 patients with pyelonephritis and urosepsis. Results The highest sensitivity and specificity (expressed as the area under the curve [AUC]) for bacterial infection were observed in serum concentration of PCT (0.952), neutrophil and lymphocyte counts (0.852 and 0.841, respectively), and serumlevels of HBP (0.837), IL-6 (0.830), and Cort (0.817). In addition, the serum levels of IFN-gamma and Cort were significantly higher and IL-8 levels were lower in CABP when compared to pyelonephritis or urosepsis. Conclusions From the novel potential biomarkers, only PCT demonstrated superiority over the routine parameters in the differentiation of bacterial from viral infections. However, some of the novel parameters should be further evaluated in larger and better characterized cohorts of patients in order to find their clinical applications.