Serum procalcitonin as a diagnostic tool of bacteremia
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KeywordsStaphylococcus Aureus Pseudomonas Aeruginosa Acne Streptococcus Pneumoniae Klebsiella Pneumoniae
Procalcitonin (PCT) is a highly specific marker of severe bacterial infections and organ failure due to sepsis. The aim of the present study was to determine the diagnostic value of serum PCT in ICU patients with bacteremia caused by either Gram-negative or Gram-positive bacteria.
During this prospective study, PCT levels were measured in 163 adult patients with proven systemic monobacterial infections. Bacteremia was defined as the recovery of any bacterial species and for coagulase-negative Staphylococci (CNS) the species that were included were those harboring the same antibiotic pattern grown from at least two consecutive samples. Blood for PCT levels and culture was drawn simultaneously at the onset of bacteremia. Eighty-eight episodes of bacteremia were caused by Gram-positive bacteria: Staphylococcus aureus 12, CNS 56, Enterococcus spp. 13, Streptococcus pneumoniae 3, Clostridium perfrigens 1 and Corynebacterium acnes 3. The remaining 75 episodes of bacteremia were caused by Gram-negative bacteria: Escherichia coli 16, Klebsiella pneumoniae 19, Pseudomonas aeruginosa 15, Acinetobacter baumannii 24, and Serratia marscensens 1. Serum PCT was estimated with an assay based on immunochemiluminescence (BRAHMS Diagnostica, Berlin, Germany).
According to our results, PCT levels in all patients with bacteremia caused by Gram-negative bacteria (75/75) were >2 ng/ml. In more details in 41 patients with Gram-negative bacteremia (54.7%) the PCT levels were 2 to 10 ng/ml and in 34 patients (45.3%) were >10 ng/ml while in patients with CNS bacteremia the PCT levels were >2 ng/ml only in 14% (6/56). In addition, in all patients with bacteremia caused by S. aureus the PCT levels were >2 ng/ml and by Streptococcus spp., C. perfrigens, and C. acnes the PCT levels were 2 to 10 ng/ml.
PCT levels were markedly higher in patients with bacteremia associated with Gram-negative bacteria than in those with Gram-positive bacteremia, especially caused by CNS. Future research is needed to confirm our results.