Procalcitonin in the early diagnosis of nosocomial sepsis in preterm neonates

Aim: To examine the diagnostic usefulness of procalcitonin (PCT), C-reactive protein and immature to total neutrophil ratio (I : T) in nosocomial sepsis among neonates treated in an intensive care unit. Methods: A retrospective analysis and comparison of diagnostic utility performed in preterm neonates using receiver operating characteristic curves for the diagnosis of culture-proven sepsis. Results: A total of 78 clinically suspected sepsis episodes in 73 newborns were analysed. The median values of PCT were: 0.56 ng/mL (interquartile range (IQR) 0.33-1.32) in group with aseptic blood culture (n = 15), 2.69 ng/mL (IQR 1.10-5.29) in Gram-positive (n = 47) and 9.36 ng/mL (IQR 3.11-39.35) in Gram-negative sepsis (n = 16). Only PCT values were significantly different (P < 0.01) among all groups. This was also true when correction for differences in blood withdrawal time was implemented. The positive and negative predictive values of PCT in the diagnosis of sepsis equalled 97.5% and 88.9%, respectively, for a cut-off value of 0.99 ng/mL. PCT was significantly better in diagnosis of sepsis than I : T (P = 0.03). No other significant differences in diagnostic efficacy were noted. The diagnostic efficacy was the highest for measurements made two or more hours since the onset of symptoms. Conclusions: The PCT serum concentration is a valuable tool for early detection of nosocomial sepsis in infants. Highest levels of PCT were observed in Gram-negative infections.