Role of bronchoalveolar lavage in differentiation between bacterial aspiration pneumonia and gastric aspiration pneumonitis

Background Differentiation between gastric aspiration pneumonitis and bacterial aspiration pneumonia is important and difficult. This study aimed to evaluate the efficacy of bronchoalveolar lavage (BAL) in differentiation between them using different biomarkers. Patients and methods Cases were divided into two groups: group A (study group) included cases admitted with suspected aspiration pneumonia. Furthermore, the cases diagnosed as aspiration pneumonia were grouped as A1 and cases diagnosed as aspiration pneumonitis were grouped as A2. Group B (control group) included cases admitted with pneumonia without risk of aspiration. Patients were subjected to history and examination, plasma C-reactive protein (CRP), serum procalcitonin (PCT), chest radiograph, and flexible bronchoscopy. BAL was collected for pH, culture and sensitivity, lipid-laden alveolar macrophages (LLAM), and starch granules. Results Serum PCT and CRP were significantly higher in group B than group A (P=0.0173 and 0.0058, respectively). BAL-pH was significantly lower in group A than group B (P=0.0115). Group A showed significantly higher frequency of positive cases with LLAM (60%) than what was recorded in group B (only 20%) (P=0.0418). Seven (35%) cases in group A and no cases in group B had positive BAL for starch granules (P=0.035). Serum PCT and CRP were significantly higher in group A1 compared with group A2. BAL-pH was significantly lower in group A2 (P<0.0001). LLAM in group A2 showed highly significant increase in the number of positive cases (P=0.007). Conclusion Analysis of BAL biomarkers (starch granules and LLAM) and cultures has important diagnostic value in differentiation between bacterial aspiration pneumonia and gastric aspiration pneumonitis.