Procalcitonin Levels in Bloodstream Infections Caused by Different Sources and Species of Bacteria

Am J Emerg Med. 2017 Apr;35(4):579-583. doi: 10.1016/j.ajem.2016.12.017. Epub 2016 Dec 10.


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.

Conclusion: PCT can distinguish between GNB and GPB infection, as well as between different bacterial species and infection sites.

Keywords: Bacterial species; Gram-negative bacteria; Gram-positive bacteria; Infection sites; Positive blood culture; Procalcitonin; Sepsis.

MeSH terms

  • Acinetobacter Infections / blood
  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii
  • Aged
  • Aged, 80 and over
  • Bacteremia / blood*
  • Bacteremia / microbiology
  • Biomarkers / blood
  • Burkholderia Infections / blood
  • Burkholderia Infections / microbiology
  • Burkholderia cepacia
  • Calcitonin / blood*
  • Catheter-Related Infections / blood*
  • Catheter-Related Infections / microbiology
  • Emergency Service, Hospital
  • Endocarditis, Bacterial / blood*
  • Endocarditis, Bacterial / microbiology
  • Enterococcus faecalis
  • Enterococcus faecium
  • Escherichia coli
  • Escherichia coli Infections / blood
  • Escherichia coli Infections / microbiology
  • Female
  • Gram-Negative Bacterial Infections / blood*
  • Gram-Negative Bacterial Infections / microbiology
  • Gram-Positive Bacterial Infections / blood*
  • Gram-Positive Bacterial Infections / microbiology
  • Humans
  • Intensive Care Units
  • Klebsiella Infections / blood
  • Klebsiella Infections / microbiology
  • Klebsiella pneumoniae
  • Male
  • Middle Aged
  • Pneumonia, Bacterial / blood*
  • Pneumonia, Bacterial / microbiology
  • Retrospective Studies
  • Staphylococcal Infections / blood
  • Staphylococcal Infections / microbiology
  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Staphylococcus haemolyticus
  • Staphylococcus hominis
  • Urinary Tract Infections / blood*
  • Urinary Tract Infections / microbiology


  • Biomarkers
  • Calcitonin