The study group consisted of 144 healthy noninfected controls and 288 patients with confirmed etiology of their infections, 185 patients with bacterial infection (Bacterial pneumonia and Streptococcal tonsillitis), 54 with viral infection, 26 with mycoplasma infection and 23 with bacterial infection as a secondary infection to influenza.
Performance of Calprotectin in diagnosis of bacterial infections as well as in distinguishing between bacterial and viral infections was compared to performance of two more investigated biomarkers, Procalcitonin (PCT) and Heparin Binding Protein (HBP). Compared to healthy subjects, all three biomarkers were significantly elevated in all diagnosis. Calprotectin level was significantly higher in all diagnosis caused by bacterial infections compared to levels in viral infections. Concentration of PCT in bacterial pneumonia was significantly higher than the concentration in the viral group, whereas the levels in Streptococcal tonsillitis and in Mycoplasma pneumoniae were not significantly different compared to levels in patients with viral infections. HBP concentration was not significantly different in viral and bacterial infections. Calprotectin was the only biomarker with ability to distinguish between bacterial infections caused by Streptococcus or Mycoplasma and viral infections.
Study results indicate that Calprotectin is a promising biomarker for diagnosis of bacterial infections as well as for differentiation between bacterial and viral infections. Calprotectin is superior to HBP in differentiation between viral and bacterial infections. It is also superior to Procalcitonin in differentiation between viral infections, and Streptococcal or Mycoplasma infections. Rapid determination of serum/plasma calprotectin might improve the management of infections and allow more selective use of antibiotics.