Accuracy of bronchoscopic alveolar lavage inflammatory biomarkers in early diagnosis of ventilator associated pneumonia in critically Ill patients

Abstract

Abstract Background Ventilator-associated pneumonia (VAP) is a frequent complication among critically ill patients in intensive care units. Its clinical diagnosis remains challenging because clinical criteria are subjective and diagnostic tests have limited ability to distinguish cases accurately. This study was conducted to validate the diagnostic ability of single and combined BAL biomarkers for identifying bacterial VAP in mechanically ventilated patients. Patients and methods This study was conducted in the respiratory, surgical, emergency, and internal medicine ICUs of the Faculty of Medicine, Zagazig University Hospitals from May to December 2025. It included 64 mechanically ventilated adult patients who underwent (BAL) for suspected (VAP). Baseline demographic, clinical, laboratory, radiological, and comorbidity data were recorded at the time of BAL. Lung ultrasound was performed within 6 h of detecting a new infiltrate on chest X-ray to assess sonographic signs suggestive of VAP .Microbiological confirmation was based on quantitative BAL cultures, with VAP diagnosed when bacterial growth reached ≥ 10⁴ CFU/mL.Patients were classified into definite VAP, indeterminate VAP, or definite absence of VAP according to clinical, imaging, microbiological, and treatment findings. Laboratory evaluation included inflammatory biomarkers such as suPAR, sTREM-1, MIF, IL-1β, and IL-8. Result The study enrolled 64 patients who were classified into three groups: Definite VAP ( n = 24), Indeterminate ( n = 15), and No VAP ( n = 25). Analysis of (BAL) fluid showed that IL-1β and suPAR were the most significant biomarkers for distinguishing Definite VAP from the other groups ( p < 0.001). IL-1β concentrations were substantially higher in Definite VAP arm, with a median of 702 pg/mL, compared with 25 pg/mL in the No VAP arm. Likewise, suPAR levels were significantly increased in Definite VAP cases (6.9 ng/mL) compared with the Indeterminate (3.3 ng/mL) and No VAP (4.6 ng/mL) groups. In contrast, sTREM-1, MIF, and IL-8 did not demonstrate significant differences among the three groups in univariate analysis. Conclusions BAL-based biomarkers, particularly IL-1β and suPAR, offer significant incremental value and may help reduce diagnostic uncertainty, inappropriate antibiotic use, and delays in targeted therapy.