The value of C-reactive protein as a marker of bacterial infection in patients with septicaemia/endocarditis and influenza.

In order to evaluate the capacity of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count (WBC) and polymorphonuclear neutrophils (PMNs) to differentiate between bacterial and viral infection we studied 176 patients with septicaemia/endocarditis (SE), 59 patients with uncomplicated influenza (UI) and 22 patients with complicated influenza (CI) retrospectively. All 4 parameters were significantly more elevated in SE and CI than in UI. Among patients with SE 10 176 had a CRP value less than 50 mg/l and in patients with UI 5/56 had a CRP value greater than 100 mg/l. Patients with SE caused by pneumococci had the highest CRP levels and patients with alfa-haemolytic streptococci the lowest. The sensitivity and specificity favours the use of CRP as an indicator of bacterial superinfection in influenza.