title: Evaluation of procalcitonin, C-reactive protein, interleukin-6 & serum amyloid A as diagnostic biomarkers of bacterial infection in febrile patients.
abstract: OBJECTIVE
  Early identification of bacterial infection in patients with fever is important for prompt treatment. However, the available parameters such as C-reactive protein (CRP) and leukocyte counts are not very specific. This study was aimed to assess the diagnostic value of procalcitonin (PCT), CRP, interleukin-6 (IL-6) and serum amyloid A (SAA) for bacterial infection in febrile patients.
  
  
  METHODS
  Serum samples were collected from febrile patients between January and December 2012 and processed for blood cultures. PCT, IL-6, CRP and SAA levels were measured. The patients were divided into three groups according to the final diagnosis: bacteraemia group (group1), bacterial infection with negative blood culture (group 2) and non-bacterial infection group (group 3).
  
  
  RESULTS
  There were significant (P<0.05) difference in the levels of PCT, CRP, IL-6 and SAA among the three groups. The PCT levels of patients with g0 ram-positive bacterial infections were lower than g0 ram-negative bacterial infections (0.53 vs 2.13, P < 0.01). The best cut-off value to detect bacterial infections was 0.26 ng/ml for PCT. PCT, CRP, IL-6 and SAA had areas under the curve of 0.804, 0.693, 0.658 and 0.687, respectively.
  
  
  CONCLUSIONS
  Our results showed PCT as a valuable marker of bacterial infections in febrile patients. PCT was superior to CRP, IL-6 or SAA in the early identification of bacterial infection. More prospective and large scale studies are warranted to confirm these findings.
authors.forename: Junyan
authors.initials: J
authors.lastname: Qu
authors.affiliation: Center of Infectious Disease, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Xiaoju
authors.initials: X
authors.lastname: L
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
mesh_terms: D040981:Acinetobacter baumannii / Q000302:isolation & purification / Q000472:pathogenicity; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001424:Bacterial Infections / Q000097:blood* / Q000473:pathology; D015415:Biomarkers / Q000097:blood*; D002097:C-Reactive Protein / Q000378:metabolism*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D004926:Escherichia coli / Q000302:isolation & purification / Q000472:pathogenicity; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011498:Protein Precursors / Q000097:blood*; D000685:Serum Amyloid A Protein / Q000378:metabolism*
chemical_list: D015415:Biomarkers; C000606589:CALCA protein, human; D015850:Interleukin-6; D011498:Protein Precursors; D000685:Serum Amyloid A Protein; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide