title: Usefulness of triggering receptor expressed on myeloid cells-1 in differentiating between typical and atypical community-acquired pneumonia.
abstract: OBJECTIVE
  The purpose of this study is to investigate the clinical use of inflammatory marker triggering receptor expressed on myeloid cells (TREM)-1 at admission for differentiating between typical and atypical bacterial community-acquired pneumonia (CAP).
  
  
  METHODS
  A prospective, noninterventional study of patients with CAP hospitalized through the emergency department was performed. Surface expression of TREM-1 was analyzed using flow cytometry on peripheral blood cells, and soluble TREM-1 (sTREM-1) concentration was determined in plasma.
  
  
  RESULTS
  Eighty-eight patients with clinical suspicion of CAP were eligible. The causative pathogen was identified in 39 patients (44.3%). After excluding 4 mixed pneumonia cases, 21 typical and 14 atypical bacterial infections were enrolled. Patients with typical bacterial CAP demonstrated increased TREM-1 surface expression on monocytes and neutrophils. Median plasma sTREM-1 levels at admission were 65.2 pg/mL (range, 17.6-138.1 pg/mL) in patients with typical CAP and 25.9 pg/mL (range, 11.5-54.8 pg/mL) in patients with atypical CAP (P < .001). Soluble TREM-1 had good discriminative value to differentiate typical from atypical pathogens with an area under the receiver operating characteristic curve of 0.87 (95% confidence interval, 0.75-0.98). At a cutoff level of 44.2 pg/mL, sTREM-1 yielded a sensitivity of 81%, a specificity of 79%, a positive likelihood ratio of 3.79, and a negative likelihood ratio of 0.24.
  
  
  CONCLUSIONS
  In newly admitted patients with CAP, determination of the TREM-1 levels may provide useful additional diagnostic information on the bacterial etiology.
authors.affiliation: Emergency Department, Taipei Veterans General Hospital, Taiwan.
authors.forename: Chorng-Kuang
authors.initials: CK
authors.lastname: How
authors.forename: Sen-Kuang
authors.initials: SK
authors.lastname: Hou
authors.forename: Hsin-Chin
authors.initials: HC
authors.lastname: Shih
authors.forename: David Hung-Tsang
authors.initials: DH
authors.lastname: Yen
authors.forename: Chun-I
authors.initials: CI
authors.lastname: Huang
authors.forename: Chen-Hsen
authors.initials: CH
authors.lastname: Lee
authors.forename: Gau-Jun
authors.initials: GJ
authors.lastname: Tang
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D016009:Chi-Square Distribution; D017714:Community-Acquired Infections / Q000378:metabolism* / Q000382:microbiology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008875:Middle Aged; D022423:Myeloid Cells / Q000378:metabolism; D018410:Pneumonia, Bacterial / Q000378:metabolism* / Q000382:microbiology; D011446:Prospective Studies; D012372:ROC Curve; D011971:Receptors, Immunologic / Q000378:metabolism*; D018709:Statistics, Nonparametric; D000073871:Triggering Receptor Expressed on Myeloid Cells-1
chemical_list: D015415:Biomarkers; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; C408842:TREM1 protein, human; D000073871:Triggering Receptor Expressed on Myeloid Cells-1