CLINICAL AND EPIDEMIOLOGICAL STUDY Evaluation of potential biomarkers for the discrimination of bacterial and viral infections P. Chalupa • O. Beran • H. Herwald • N. Kaspr ˇı ´kova ´ • M. Holub Received: 9 November 2010 / Accepted: 31 May 2011 / Published online: 1 July 2011 Ó Springer-Verlag 2011 Abstract Purpose Timely knowledge of the bacterial etiology and localization of infection are important for empirical anti- biotic 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 Infec- tious 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-1b, IL-6, IL-8, IL-10, IL-12, TNF-a, IFN-c, 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 pneumo- nia (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 serum levels of HBP (0.837), IL-6 (0.830), and Cort (0.817). In addition, the serum levels of IFN-c 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. Keywords Bacterial infection Á Viral infection Á Infectious focus Á Biomarkers Á Evaluation Á Discrimination Abbreviations S-PCT Serum level of procalcitonin S-HBP Serum level of heparin-binding protein S-Cort Serum level of cortisol Purpose Timely knowledge of the bacterial or viral etiology of infection is necessary for appropriate treatment, including empirical antibiotic therapy. Because the clinical symp- toms of severe viral and bacterial infections are often similar, clinicians need reliable diagnostic biomarkers in order to make treatment decisions. Currently, C-reactive protein (CRP), white blood cell (WBC) counts, and neu- trophil counts are the most frequently used biomarkers in P. Chalupa Á O. Beran Á M. Holub (&) Department of Infectious and Tropical Diseases, First Faculty of Medicine, Charles University in Prague and University Hospital Bulovka, Budı ´nova 2, 180 81 Prague 8, Czech Republic e-mail: michal.holub@lf1.cuni.cz H. Herwald Department of Clinical Science, Division of Infection Medicine, Lund University, Lund, Sweden N. Kaspr ˇı ´kova ´ Institute of Biophysics and Informatics, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic 123 Infection (2011) 39:411–417 DOI 10.1007/s15010-011-0126-4