C-Reactive Protein and Serum Procalcitonin Levels as Markers of Bacterial Upper Respiratory Tract Infections

Abstract

Problem statement: Upper Respiratory Tract Infections (URTIs) are the most frequent of the community with major social and financial impact. Hence, early and proper diagnosis is of utmost importance. Biomarkers such as the circulating levels of Procalcitonin (PCT) have been shown to be elevated in systemic bacterial infections, but remain relatively low in viral infections and inflammatory diseases and have been suggested as signals for the initiation of antimicrobial therapy. Experience evaluating the value of PCT as a marker of URTIs is limited. Approach: Forty patients with bacterial URTIs were studied in order to assess the role of PCT, measured by using the semi-quantitative test, as bacterial inflammation marker and to compare with other markers, such as C-Reactive Protein (CRP), White Blood Cell (WBC) counts and Polymorphonuclear (PMN) cell counts. Results: In all cases, 22 with tonsillopharyngitis, 10 with peritonsillar abscess and 8 with rhinosinusitis, PCT levels remained below detection limits. On the other hand, serum CRP levels strongly correlated with body temperature, WBC and PMN cell counts. Patients with rhinosinusitis were older than those with peritonsillar abscess, had lower body temperature than those with tonsillopharyngitis and had lower serum CRP levels than patients with either peritonsillar abscess or tonsillopharyngitis. Conclusion: Therefore CRP could be used as a marker to predict the severity of URTIs while PCT, although promising in cases of other severe bacterial infections, did not prove to be suitable for patients with less severe or localized infections, such as URTIs.