Role of cytokines (interleukin-1β, 6, 8, tumour necrosis factor-α, and soluble receptor of interleukin-2) and C-reactive protein in the diagnosis of neonatal sepsis

Aim: To investigate whether the serum levels of interleukin-1beta, 6, 8, tumour necrosis factor-alphaa and the soluble receptor of IL-2 are useful in the diagnosis of neonatal sepsis, and whether their diagnostic power is increased when in combination with classical markers such as C-reactive protein and white blood cell count. Methods: Blood samples were collected at admission from 40 neonates with suspected infection. Patients were included in different groups according to the bacteriological and laboratory results: Group I consisted of 20 newborns with positive blood cultures and other biological tests suggestive of infection. Group II included 20 neonates with negative blood cultures and biological tests not suggestive of infection. The control group included 20 healthy neonates with no clinical or biological data of infection. Results: Mean values of C-reactive protein were significantly higher in Group I. No differences were found between the groups for white blood cell count, with the exception of the presence of leucocytosis in Group II. Levels of interleukin-1beta, 6, 8, tumour necrosis factor-alpha, soluble receptor of interleukin-2, and C-reactive protein were significantly higher in infected neonates than in the control groups. Detection sensitivity and specificity were 80 and 92% for C-reactive protein, 60 and 87% for interleukin-1beta, 61 and 80% for interleukin-6, 62 and 96% for interleukin-8, 54 and 92% for tumour necrosis factor-a and 63 and 94% for soluble receptor of interleukin-2. The discriminant analysis showed that the best combination for sepsis diagnosis was C-reactive protein + interleukin-8 + soluble receptor of interleukin-2, with a sensitivity of 85% and a specificity of 97.1%. Conclusion: Our study suggests that no individual test can on its own identify infected neonates, and that although the combination of C-reactive protein, interleukin-8 and the soluble receptor of interleukin-2 exhibits a high specificity, its sensitivity is limited.