Procalcitonin Levels in Gram-Positive, Gram-Negative, and Fungal Bloodstream Infections

Abstract

Procalcitonin (PCT) can discriminate bacterial from viral systemic infections and true bacteremia from contaminated blood cultures. The aim of this study was to evaluate PCT diagnostic accuracy in discriminating Gram-positive, Gram-negative, and fungal bloodstream infections. A total of 1,949 samples from patients with suspected bloodstream infections were included in the study. Median PCT value in Gram-negative (13.8 ng/mL, interquartile range (IQR) 3.4–44.1) bacteremias was significantly higher than in Gram-positive (2.1 ng/mL, IQR 0.6–7.6) or fungal (0.5 ng/mL, IQR 0.4–1) infections (P < 0.0001). Receiver operating characteristic analysis showed an area under the curve (AUC) for PCT of 0.765 (95% CI 0.725–0.805, P < 0.0001) in discriminating Gram-negatives from Gram-positives at the best cut-off value of 10.8 ng/mL and an AUC of 0.944 (95% CI 0.919–0.969, P < 0.0001) in discriminating Gram-negatives from fungi at the best cut-off of 1.6 ng/mL. Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative Gram-negative bacteria (17.1 ng/mL, IQR 5.9–48.5 versus 3.5 ng/mL, IQR 0.8–21.5; P < 0.0001). This study suggests that PCT may be of value to distinguish Gram-negative from Gram-positive and fungal bloodstream infections. Nevertheless, its utility to predict different microorganisms needs to be assessed in further studies.

Procalcitonin, c-reactive protein, leukocyte, mean platelet volume levels in bloodstream infections

“…The diagnostic accuracy of PCT for this differentiation was determined by ROC analysis, revealing an optimal cutoff value of 3.11 ng/mL, resulting in 93.3% specificity and 63.9% sensitivity [16]. In a similar study, Leli et al [18] found that an optimal PCT cutoff value of 1.6 ng/mL could be used to distinguish GN infections from fungal infections with 96% specificity and 77% sensitivity. Martini et al [19] also demonstrated that an optimal PCT cutoff value of 2 ng/mL could be used to distinguish Candida sepsis from bacterial sepsis with 92% sensitivity and 93% specificity.…”

“…According to several studies, low concentrations of PCT in critically ill patients might suggest fungal infection. Thus, PCT levels could be used specifically and sensitively to distinguish GN sepsis from fungal sepsis [15,16,17]. The diagnostic accuracy of PCT for this differentiation was determined by ROC analysis, revealing an optimal cutoff value of 3.11 ng/mL, resulting in 93.3% specificity and 63.9% sensitivity [16].…”

“…Furthermore, patients treated with broad-spectrum antibiotics and invasive surgeries have a greater risk of developing fungal infections, and therefore such patients with elevated PCT levels should be screened for fungal infections [19]. PCT levels have been shown to be able to distinguish GN bacterial sepsis from GP bacterial and fungal sepsis [15,16,20]. Charles et al reported that an optimal PCT cutoff value of 16 ng/mL resulted in 75.0% sensitivity and 82.2% specificity in distinguishing GN sepsis from GP sepsis.…”

Procalcitonin-guided antibiotic treatment in critically ill patients

“…In a critically ill patient with clinical sepsis, Gram-negative bacteraemia seems to be associated with higher PCT levels than Gram-positive bacteraemia [14]. Although the mechanism underlying different PCT production in response to different bacterial pathogens is not completely clear, it could possibly be explained by the different interactions of Grampositive or Gram-negative bacteria with host's cells and different pathogen-associated molecular patterns [41]. E. coli bacteraemia/sepsis usually triggers an extremely high, S. aureus bacteraemia/sepsis only a moderate rise of PCT levels.…”

Diagnostic Usefulness of Procalcitonin and C-Reactive Protein in Gram Negative Bacterial Infections.

“…Additional results showed a significant difference in median PCT values between Enterobacteriaceae and nonfermentative G-bacteria. 4 An early diagnosis of bacteraemia is crucial to facilitate adequate treatment of severe infections. A PCT level > 2 ng/mL was reported in 71% cases in G-bacteraemia patients, whereas in patients with G+ bacteraemia this level of PCT was reported only in 33%.…”