Diagnostic utility of the soluble triggering receptor expressed on myeloid cells-1 in bronchoalveolar lavage fluid from patients with bilateral lung infiltrates

Background Differential diagnosis of patients with bilateral lung infiltrates remains a difficult problem for intensive care clinicians. Here we evaluate the diagnostic role of soluble triggering receptor expressed on myeloid cells-1 ( sTREM-1) in bronchoalveolar lavage ( BAL) specimens from patients with bilateral lung infiltrates. Methods We conducted a prospective observational study on 80 patients with bilateral lung infiltrates with clinical suspicion of infectious pneumonia. Patients were categorized into three groups: bacterial or fungal infection, intracellular or viral infection, and noninfectious inflammatory disease. sTREM-1 concentrations were measured, and BAL fluid and Clinical Pulmonary Infection Score ( CPIS) were analyzed. Results The sTREM-1 concentration was significantly increased in patients with bacterial or fungal pneumonia ( n = 29, 521.2 +/- 94.7 pg/ ml), compared with that in patients with viral pneumonia, atypical pneumonia or tuberculosis ( n = 14, 92.9 +/- 20.0 pg/ ml) or noninfectious inflammatory disease ( n = 37, 92.8 +/- 10.7 pg/ ml). The concentration of sTREM-1 in BAL fluid, but not CPIS, was an independent predictor of bacterial or fungal pneumonia, and a cutoff value of more than 184 pg/ ml yielded a diagnostic sensitivity of 86% and a specificity of 90%. Conclusion The sTREM-1 level in BAL fluid from patients with bilateral lung infiltrates is a potential marker for the differential diagnosis of pneumonia due to extracellular bacteria.