Serum IL-6, IL-8 and CRP as Markers for Prediction of Bacteremia byGram Negative Rods in Febrile Cancer Patients and in Irradiated Rats

In this study, serum inflammatory mediator’s levels (IL-6 and IL-8) at fever onset to predict gram negative bacteremia in cancer patients have been determined. Also, the effect of gamma irradiation on IL-6 serum levels has been investigated using animal model at dose level 24.4 Gy. Seventy feverish in-patients were enrolled in the study. Blood samples were collected at onset of fever for assay of IL-6, IL-8, CRP, C3 and total leukocytic count. IL-6 and IL-8 serum levels were higher in patients with gram negative bacteremia than in those with non-microbial fever. For patients with gram negative bacteremia and those without there was significant difference in IL-6 and IL-8 serum levels (P=0.0001 and P=0.0059 respectively). While, CRP and C3 serum levels showed non-significant differences. Using (ROC), IL-6 was potentially useful with Sp, NPV of 100% and 398.6 pg/ml cut-off value and AUC of 1.000 compared to Sp 77.8%, NPV 60% and AUC of 0.844 for CRP. On the other hand, IL-8 values didn't show overlapping in the groups. In the animal model, (ROC) for IL-6 serum concentration in bacteremia groups (due to Pseudomonas aeruginosa and Klebsiella pneumoniae) with exposure to gamma radiation and bacteremia groups without exposure to gamma radiation showed a cut-off value of 25740 pg/ml with 58.3% Sn, NPV 64.3%. These results showed the potential usefulness of IL-6 and IL-8 as early predictors of gram-negative bacteremia than commonly used markers such as CRP and C3. Also, usefulness of serum IL-6 as marker discriminating between different fever episodes in cancer patients under radiotherapy.