title: Procalcitonin levels in bloodstream infections caused by different sources and species of bacteria.
abstract: OBJECTIVE
  The aim of this study was to evaluate procalcitonin (PCT) diagnostic accuracy in discriminating gram-negative (GN) from gram-positive (GP) bloodstream infections and determining the relationship between PCT levels, infection sites, and pathogen types.
  
  
  METHODS
  Clinical and laboratory data were collected from patients with blood culture (BC)-positive sepsis between January 2014 and December 2015. PCT levels at different infection sites were compared, as was the presence of GN and GP bloodstream infection. A receiver operating characteristic (ROC) curve was generated to assess diagnostic accuracy.
  
  
  RESULTS
  Of the 486 monomicrobial BCs, 254 (52.26%) were positive for GN bacteria (GNB), and 202 (42.18%) for GP bacteria (GPB). Median PCT levels were higher in BCs positive for GN (2.42ng/ml, IQR: 0.38-15.52) than in those positive for GPB (0.49ng/ml, IQR: 0.13-5.89) (P<0.001). In the ROC analysis to differentiate between GNB and GPB, the area under the curve was 0.628 (95% CI: 0.576-0.679). When the cutoffs for PCT were 10.335 and 15.000ng/ml, the specificity of GNB infection was 80.2% and 84.2%, respectively. PCT levels caused by GNB differed between Escherichia coli and Acinetobacter baumanni/Burkholderia cepacia, Klebsiella pneumonia and Acinetobacter baumanni. PCT levels caused by GPB differed between Staphylococcus epidermidis/Staphylococcus aureus and Staphylococcus hominis/Staphylococcus haemolyticus, Enterococcus faecium and Enterococcus faecalis/S.hominis/S. haemolyticus. Among patients with known infection sites, there were statistical differences in PCT levels between abdominal infection and pneumonia/infective endocarditis, urinary tract infection and pneumonia/catheter-related infection/infective endocarditis.
  
  
  CONCLUSIONS
  PCT can distinguish between GNB and GPB infection, as well as between different bacterial species and infection sites.
authors.affiliation: Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Sheng Tao
authors.initials: ST
authors.lastname: Yan
authors.affiliation: Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Li Chao
authors.initials: LC
authors.lastname: Sun
authors.affiliation: Clinical Microbiology Unit, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Hong Bing
authors.initials: HB
authors.lastname: Jia
authors.affiliation: Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Gao
authors.affiliation: Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Jian Ping
authors.initials: JP
authors.lastname: Yang
authors.affiliation: Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing, China. Electronic address: zhangchong2003@vip.sina.com.
authors.forename: Guo Qiang
authors.initials: GQ
authors.lastname: Zhang
mesh_terms: D000151:Acinetobacter Infections / Q000097:blood / Q000382:microbiology; D040981:Acinetobacter baumannii; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000097:blood* / Q000382:microbiology; D015415:Biomarkers / Q000097:blood; D019121:Burkholderia Infections / Q000097:blood / Q000382:microbiology; D016956:Burkholderia cepacia; D002116:Calcitonin / Q000097:blood*; D055499:Catheter-Related Infections / Q000097:blood* / Q000382:microbiology; D004636:Emergency Service, Hospital; D004697:Endocarditis, Bacterial / Q000097:blood* / Q000382:microbiology; D013293:Enterococcus faecalis; D016984:Enterococcus faecium; D004926:Escherichia coli; D004927:Escherichia coli Infections / Q000097:blood / Q000382:microbiology; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000097:blood* / Q000382:microbiology; D016908:Gram-Positive Bacterial Infections / Q000097:blood* / Q000382:microbiology; D006801:Humans; D007362:Intensive Care Units; D007710:Klebsiella Infections / Q000097:blood / Q000382:microbiology; D007711:Klebsiella pneumoniae; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000097:blood* / Q000382:microbiology; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000097:blood / Q000382:microbiology; D013211:Staphylococcus aureus; D013212:Staphylococcus epidermidis; D041162:Staphylococcus haemolyticus; D041181:Staphylococcus hominis; D014552:Urinary Tract Infections / Q000097:blood* / Q000382:microbiology
chemical_list: D015415:Biomarkers; D002116:Calcitonin
keywords: Bacterial species; Gram-negative bacteria; Gram-positive bacteria; Infection sites; Positive blood culture; Procalcitonin; Sepsis