The diagnosis of ventilator associated pneumonia (VAP) is both contentious and frustrating for the intensivist. This study evaluates the effectiveness of using soluble triggering receptor expressed on myeloid cells (sTREM)-1, a member of the immunoglobulin superfamily expressed in response to bacterial or fungal infections, as a tool for the rapid diagnosis of VAP. A total of 148 patients requiring mechanical ventilation and with a clinical suspicion of pneumonia were prospectively enrolled in the study. Mini bronchoalveolar lavage was performed and the collected sample used for quantitative bacterial culture and assay of sTREM-1 and the inflammatory cytokines tumour necrosis factor (TNF)-α and interleukin (IL)-1β. VAP was diagnosed on the basis of new persistent infiltrates on chest radiography, significant bacterial growth on culture (⩾10³ CFU/ml of lavage fluid), and either purulent tracheal secretions, pyrexia, leucocytosis, or leucopenia. The sTREM-1 assay reliably diagnosed pneumonia with a sensitivity of 98% and specificity of 90%. Using multiple logistic regression analysis among the predictors of pneumonia (clinical pulmonary infection score, sTREM-1, TNF-α and IL-1β), sTREM-1 emerged as the strongest indicator (odds ratio 41.5).

The authors conclude that sTREM-1 assay may be a useful tool in both the rapid diagnosis of VAP and the reliable differentiation from non-infectious causes of fever and radiographic pulmonary infiltrates in ventilated patients.