Abstract
BACKGROUND: Currently-available conventional diagnostic tests to identify the causative pathogen of community-acquired pneumonia in children have several limitations. However, the lack of timely and accurate etiological diagnosis could substantially affect childhood pneumonia outcomes. Therefore, this study assessed the efficacy of cytological analysis of bronchoalveolar lavage fluid (BALF) in rapidly distinguishing between bacterial and non-bacterial pneumonia in paediatric patients. PATIENTS: We enrolled patients with community-acquired pneumonia who underwent bronchoalveolar lavage at the Affiliated Hospital of Guangdong Medical University. Pathogens were detected in the BALF, and BALF cytological analysis was performed. RESULTS: Overall, 154 patients were enrolled, among whom 141 had pneumonia (68 severe cases), with 116 cases of bacterial pneumonia and 25 cases of viral pneumonia. The bacterial pneumonia group exhibited a significantly higher neutrophil percentage in the BALF (BALF-NE%) than the viral pneumonia group (p<0.001). Additionally, 100% (13/13), 96.0% (24/25), and 89.7% (104/116) of cases in the control, viral pneumonia, and bacterial pneumonia groups had a BALF-NE% ≤10%, ≤30%, and >30%, respectively. The area under the receiver operating characteristics curve for diagnosing bacterial pneumonia using BALF-NE% was 0.986 (95% confidence interval: 0.963-1.000, standard error: 0.012) (p<0.0001), surpassing that of the white blood cell count, NE%, C-reactive protein level, and procalcitonin level. When setting the threshold to BALF-NE% >28%, the sensitivity and specificity for diagnosing bacterial pneumonia were 98.8% and 94.1%, respectively. Among patients with pneumonia caused by Chlamydia pneumoniae, Mycoplasma pneumoniae, and Bordetella pertussis, the proportions with a BALF-NE% >70% were 92.3% (12/13), 100% (16/16), and 80.0% (8/10), respectively. CONCLUSION: The BALF-NE% outperforms conventional diagnostic indicators and allows reliable, rapid differentiation between bacterial and viral pneumonia in children.