Diagnostic Utility of HBP, PCT, and CRP in Identifying Bacterial Complications in Severe COVID-19

To address the challenge of delayed bacterial infection diagnosis in critically ill COVID-19 patients, we evaluated the performance of serum procalcitonin (PCT), C-reactive protein (CRP), and heparin-binding protein (HBP), and bronchoalveolar lavage fluid HBP as potential biomarkers for guiding antibiotic therapy.

Patients meeting the inclusion criteria for severe and critical COVID-19 were enrolled as the case group, while age- and gender-matched healthy individuals were selected as the control group. Levels of PCT, CRP, and HBP were measured. The case group was further stratified based on bacterial culture results, and differences in serum, sputum, or bronchoalveolar lavage fluid markers were subjected to statistical analysis.

Plasma levels of PCT and HBP were significantly higher in patients with bacterial infection compared to both the COVID-19 group and the healthy control group, while CRP was only significant in distinguishing cases from the healthy control group. The AUC for PCT in differentiating COVID-19 patients from those with bacterial infection was 0.937 with a sensitivity of 0.828 and specificity of 0.933, while the AUC for CRP was 0.564 with a sensitivity of 0.828 and specificity of 0.400. The AUC for HBP was 0.775 with a sensitivity of 0.690 and specificity of 0.967. The combined detection of PCT+CRP+HBP exhibited the highest diagnostic performance, with an AUC of 0.978, a sensitivity of 0.966, and a specificity of 0.933.

The combined detection of PCT, CRP, and HBP can enable more precise classification of COVID-19 patients with concurrent bacterial infections and inform the optimal timing of antibiotic initiation.