Objective To investigate the potential role of soluble triggering receptor expressed on ayeloid cells-1(sTREM-1) expression in serum,endotracheal aspiration (ETA),bronchoalveolar lavage fluid (BALF) and exhaled breath condensate (EBC) as early biomarkers for the diagnosis of ventilator-associated pneumonia (VAP) in patients with acute ischemic stroke.Methods One hundred and thirty-two patients with clinically suspected VAP were prospectively included in this multicenter study.The levels of sTREM-1 in serum,ETA,BALF and EBC were analyzed for diagnostic evaluation at the time of VAP clinically suspected.The bacterial count over 104/CFU as a gold standard for VAP,and the receiver operating characteristic curves were used to identify the ideal cutoff values.Results VAP was confirmed in 76 patients (57.58％).In VAP patients (VAP group) and non-VAP patients (non-VAP group),the level of sTREM-1 in BALF was 32.35 (30.08-41.72) and 18.92(11.89-31.72) ng/L,and the level of sTREM-1 in EBC was 1.57 (1.02-2.61) and 0.41(0.19-1.61)ng/L respectively.The level of sTREM-1 in BALF and in EBC in VAP group was significantly higher than that in non-VAP group (P ＜0.05).The optimum cutoff value for sTREM-1 in BALF according to the maximum Youden index was 23.61 ng/L.This cutoff value had 85.5％ sensitivity and 73.1％ specificity,with 0.813 area under the curve.sTREM-1 in BALF had excellent correlation with that in EBC (R2 =0.78,P ＜ 0.05).Conclusions The results of this prospective study suggest that sTREM-1 levels in BALF and EBC have better roles in facilitating the diagnosis of VAP and thus may be practically recommended to guide the administration of antibiotics when VAP is suspected.