Expression of the triggering receptor expressed on myeloid cells-1 mRNA in a heterogeneous infected population

This study is to investigate the clinical utility of detection of peripheral blood triggering receptor expressed on myeloid cells (TREM)-1 mRNA as an early indicator of sepsis among critically ill patients and to compare the results of TREM-1 with those of C-reactive protein (CRP). A prospective, non-interventional study of 127 patients with at least two criteria of the systemic inflammatory response (SIRS) was performed. TREM-1 was assessed by real-time quantitative reverse transcription-polymerase chain reaction. The diagnosis of SIRS only was made in 41 patients (32%), and the diagnosis of sepsis was made in other 86 patients (68%). TREM-1 mRNA expression had the comparably discriminative value to differentiate the presence from the absence of infection, with an area under the receiver-operating characteristic curve (AUC) of 0.75 [95% confidence interval (95% CI), 0.67-0.84] than CRP [AUC, 0.72 (95% CI, 0.62-0.81)]. As an indicator of sepsis, a TREM-1 mRNA expression ratio cutoff value of 58.8 had a sensitivity of 72%, a specificity of 71%, a positive likelihood ratio of 2.5 and a negative likelihood ratio of 0.39. Furthermore, TREM-1 mRNA expression was selectively higher in septic patients caused by extracellular bacteria or fungi [112.4 (19.3-680.1)], than in those caused by intracellular bacteria or viruses [18.8 (7.6-53.0), p < 0.001]. There was no difference in plasma CRP levels between both septic groups (p = 0.782). TREM-1 and CRP are similar diagnostic markers of sepsis. The different ability of extracellular and intracellular pathogens to induce TREM-1 expression may provide a potential marker for differential diagnosis.