Heparin-binding protein and procalcitonin in the diagnosis of pathogens causing community-acquired pneumonia in adult patients: a retrospective study

Abstract

The performance of inflammatory markers in community-acquired pneumonia (CAP) caused by different pathogens has not been fully studied. We sought to find the differences in the concentrations of procalcitonin (PCT) and heparin-binding protein (HBP) between patients with CAP caused by different pathogens. We enrolled 162 patients with CAP, divided into three groups on the basis of bacterial (n = 108), fungal (n = 21) and viral (n = 33) infection. Complete leukocyte counts and the concentration of HBP and PCT were measured, and the differences were compared with nonparametric tests. The receiver operating characteristic (ROC) curve was used to evaluate the significant differences in the sensitivity and specificity of the indicators. The leukocyte and neutrophils counts and the concentrations of HBP and PCT in the viral group were significantly lower than those in the other two groups (p < 0.001). The area under the ROC curve (AUC) of the concentration of HBP and PCT as well as leukocyte and neutrophils counts were 0.927, 0.892, 0.832 and 0.806 for distinguishing bacterial from viral infection, respectively. The best cut-off value was 20.05 ng/mL for HBP, with a sensitivity of 0.861 and specificity of 0.939. The best cut-off value was 0.195 ng/mL for PCT, with a sensitivity of 0.991 and specificity of 0.636. The best cut-off value was 5.195 × 10⁹/L and 4.000 × 10⁹/L for leukocyte and neutrophils counts, with sensitivity of 0.694 and 0.880 and specificity of 0.667 and 0.636, respectively. The AUC of HBP, PCT and leukocyte and neutrophil counts for distinguishing fungal from viral infection were 0.851, 0.883, 0.835 and 0.830, respectively. The best cut-off values were 29.950 ng/mL, 0.560 ng/mL, 5.265 × 10⁹/L and 3.850 × 10⁹/L, with sensitivity of 0.667, 0.714, 0.905 and 0.952 and specificity of 0.970, 0.879 0.667 and 0.606, respectively. There were no significant differences in the three indicators between the bacterial and fungal infection groups. The concentration of CRP showed no significant differences among the three groups. Consequently, the stronger immune response characterized by higher inflammation markers including HBP and PCT can help distinguish bacterial and fungal CAP from viral CAP.

Keywords: C-reactive protein; Community acquired pneumonia; Heparin-binding protein; Procalcitonin.

Figure 1. The concentration of inflammatory markers in peripheral plasma of three groups.

The concentrations of HBP (A), CRP (B), PCT (C) as well as the counts of leukocyte (D) and neutrophils (E) in the bacterial, fungal and viral groups. note: HBP, heparin-binding protein; CRP, C-reactive protein; PCT, procalcitonin; NS, no significance; ***, P < 0.001.

Figure 2. The sensitivity and specificity of inflammatory markers for distinguishing bacterial infection and fungal infection from viral infection.

(A) The AUC of HBP, PCT, leukocyte and neutrophils counts for distinguishing bacterial infection from virus infection are 0.927, 0.892, 0.832 and 0.806, respectively. (B) The AUC of HBP, PCT, leukocyte and neutrophils counts for distinguishing fungal infection from virus infection are 0.851, 0.883, 0.835 and 0.830, respectively.