Triggering receptor (TREM-1) expressed on myeloid cells predicts bacteremia better than clinical variables in community-acquired pneumonia

Background and objective: Some clinical variables are associated with bacteremia in patients with community-acquired pneumonia (CAP). The aim of this study was to analyse the accuracy of the soluble form of triggering receptor expressed on myeloid cells-1 (sTREM-1) to predict positive blood cultures in comparison with established clinical prognostic variables. Methods: In addition to collecting clinical and laboratory information, a commercially available immunoassay kit was used to measure the serum sTREM-1 levels on the first day of admit ion in patients with CAP. Receiver operating characteristic (ROC) curves were used to compare the ability of sTREM-1 and commonly used clinical variables to identify bacteremia. Results: Blood cultures yielded a pathogen in 13 (10.4%) out of 124 patient samples. The microorganisms isolated were Streptococcus pneumoniae (11 patients) and Klebsiella pneumoniae (2 patients). The presence of pleuritic chest pain, tachycardia and extreme white cell count (WCC) were associated with bacteremia. However, ROC curve analysis showed an accuracy of sTREM-1 (area under the receiver operating characteristic curve (AUC) 0.84, 95% CI: 0.72-0.95), which was higher than pleuritic chest pain (AUC 0.71, 95% CI: 0.57-0.84), tachycardia (AUC 0.73, 95% CI: 0.58-0.88) and extreme WCC (AUC 0.70, 95% CI: 0.55-0.85) for predicting positive blood cultures. Low admission sTREM-1 serum values had a high negative predictive value for excluding bacteremia (sTREM-1 <120 pg/mL = 98.8%). Conclusions: This preliminary study suggests that the determination of sTREM-1 serum levels on admission may be more accurate than clinical variables for identifying bacteremic patients.