Correlation of procalcitonin values with sepsis in blood cultures

Abstract

Background: In patients with bacterial or fungal infections, serum procalcitonin (PCT) levels vary and are substantially elevated in patients with Gram-negative bacteraemia. The study evaluates the diagnostic accuracy of PCT levels in patients with positive blood culture (BC) results for Gram-negative sepsis and a comparison is made with PCT levels.

Methods: The study analysed data of 180 patients with a diagnosis of sepsis. Data consisted of all diagnostic episodes of BC and PCT values. The diagnostic performance of PCT was calculated using the receiver operating curve (ROC) characteristics.

Results: A total of 180 episodes met the inclusion criteria. According to BC classifications, a significantly higher value of PCT was observed in bloodstream infections caused by Gram-negative bacteria (14.5 ng/ml, interquartile range [IQR] 3.8–32.0) when compared to bloodstream infections caused by Gram-positive bacteria (3.0 ng/ml, [IQR] 0.05–6.4) or Candida species. (0.8 ng/ml, [IQR] 0.3–1.0). ROC analysis revealed an optimal cut off value of 9.5 ng/ml for PCT when discriminating Gram-negative sepsis from Gram-positive sepsis, which  yielded a sensitivity of 60.0% and specificity of 71.0%. An optimal cut-off value of 1.2 ng/ml for PCT was used, when discriminating Gram-negative sepsis from fungal sepsis. The PCT test had a sensitivity and specificity of 70.0% and 93.0% respectively.

Conclusion: In patients with Gram-negative sepsis, the serum PCT levels were significantly higher than in thos with Gram-positive or fungal sepsis. Therefore, to differentiate Gram-negative sepsis from Gram-positive and fungal sepsis, PCT could be a possible marker.