Plasma procalcitonin levels remain low at the onset of gram-positive bacteremia regardless of severity or the presence of shock: A retrospective analysis of patients with detailed clinical characteristics.

Objectives: Procalcitonin (PCT) is an early diagnosis marker of sepsis/bacteremia. However, some reports refer to its lower responsiveness to gram-positive bacteremia. We retrospectively evaluated the PCT values at the onset of bacteremia in relation to severity index.
Methods: Patients with bacteremia caused by two gram-negative bacteria (46 E. coli and 50 Klebsiella pneumoniae) and three gram-positive bacteria (45 S. aureus, 56 S. epidermidis, and 10 S. mitis) were studied. The plasma PCT and C-reactive protein (CRP) levels were compared between species and different Sequential Organ Failure Assessment (SOFA) score groups.
Results: The median PCT level was higher in gram-negative than in gram-positive bacteremia in overall (13.09 vs. 0.50 ng/mL, p < 0.0001), in SOFA score≥4 group (28.85 vs.1.72 ng/mL, p < 0.0001) and in SOFA<4 group (2.64 vs. 0.42 ng/mL, p < 0.0001). Only 46%, and 11% of patients showed PCT ≥0.5 ng/mL in S. epidermidis, and S. mitis bacteremia, respectively. PCT was significantly better than CRP in discriminating gram-negative from gram-positive bacteremia (AUCROC; 0.828 and 0.634, p < 0.001), but it was low in Staphylococcus epidermidis bacteremia regardless of SOFA scores.
Conclusions: PCT levels are lower in gram-positive bacteremia regardless of SOFA scores or the presence of shock. The conventional sepsis cutoff of 0.5 ng/mL may overlook certain proportions of gram-positive bacteremia.
Competing Interests: Declaration of competing interest None of the authors have financial relationships with any commercial entity with an interest in the subject of this manuscript.
(Copyright © 2020. Published by Elsevier B.V.)