The Significance Of Measurement Of Serum Interleukin-8 In Combination With C-reactive Protein In Diagnosis Of Bacterial Infection And Rational Use Of Antibiotics In Neonate

Background and purposeBacterial infections contribute significantly to morbidity and mortality in newborn infants.Successful treatment depends on early initiation of appropriate antibiotic therapy, but early diagnosis of neonatal bacterial infections is difficult because clinical signs are nonspecific and may initially be subtle.Therefore, a frequently adopted strategy is to start antibiotics in all infants with clinical signs or obstetric risk factors suggesting infection.Consequently,on retrospective reevaluations, the majority of infants received antibiotics "unnecessarily".In light of the ever-increasing emergence of resistant bacteria, restrictive use of antibiotic therapy is indispensable and efforts to ensure a more cautious use of antibiotic therapy in newborn infants are important. The use of laboratory tests to rule out infection was suggested to reduce unnecessary antibiotic therapy.C-reactive protein (CRP), an marker for established neonatal bacterial infections,is not useful for early diagnosis.Interleukin-8 (IL-8), a proinflammatory cytokine,rises early in thecourse of neonatal bacterial infections. Studies suggested that measurements of IL-8 and CRP may help to reduce unnecessary antibiotic therapy, and this diagnostic strategy seemed to be safe.This study was designed to test a diagnostic algorithm that includes measurements of interleukin-8 and C-reactive protein 1) is a sensitive test for diagnosing neonatal bacterial infection early and 2) provides clues for diagnosing neonatal infection early and decide whether to start antibiotic therapy in infants with "suspected infection signs" and 3) finds the clinical phenomenon of excessive antibiotic therapy and reduces unnecessary antibiotic therapy in neonates.Materials and methods1. Objects and groupingPatients admitted to the neonatal intensive care unit of the Third Affiliated Hospital of Zhengzhou University between December,2009 and November,2010 were included in the study. Patients with infection or suspected infection were divided into three groups:the clinical infection group:50 infants who were diagnosed as neonatal sepsis or pneumonia; the suspected infection group:50 infants who have more than one "suspected infection signs";the control group:50 preterm or full-term infants without infection or suspected infection in the same period.2. MethodsBlood samples for determining serum IL-8, CRP, and hematological parameters (total leukocyte count, differential count, platelet count) were collected from all the neonates in this study before starting treatment,and neonates in each group start antibiotic therapy based on their own standard. Measurement of serum IL-8 and CRP in the clinical infection group and in the suspected infection group were repeated on the 7th and 14th day of treatment if these were necessary based on their own standard. Neonates in the control group did not determine serum IL-8, CRP again.3. Statistics analysisAll the results were presented as the mean±tandard deviation(x±S),and were analysed by SPSS10.0 statistical software. One-way analysis of variance was used to compare the means during groups,and LSD-t test was used between groups. P<0.05 was considered as statistically significant. Paired-sample t test was used to compare the means before and after treatment in the same group, but independent-sample t test was used in different groups. P<0.05 was considered as statistically significant. Count data was analysed by Chi-square test. P<0.05 was considered as statistically significant.Results1. Comparison of serum IL-8 and CRP levels before and after treatment during groupsSerum IL-8 and CRP levels before treatment in the clinical infection group and in the suspected infection group were significantly different compared with the control group,and they were significantly higher in the clinical infection group than these in the suspected infection group and in the control group,and these were significantly higher in the suspected infection group than in the control group.There was no statistical significance of white blood cell count during groups. Serum IL-8 and CRP levels before treatment were significantly higher than these after treatment in the clinical infection group and the suspected infection group. Serum IL-8 and CRP levels on the 7th day of treatment in the suspected infection group and on the 14th day of treatment in the clinical infection group were no statistical significance compared with these in the control group. Serum IL-8 levels on the 7th day of treatment in the clinical infection group were significantly higher than these before treatment in the suspected infection group,while there was no statistical significance of serum CRP levels between them.2. Comparison of the rates of antibiotic therapy in each groupThe rates of antibiotic therapy in the suspected infection group according to the indications for antibiotic therapy on the 7th day of treatment were 22% higher than these based on IL-8≥70pg/ml and or CRP>10mg/L, and the difference was statistically significant. The rates of antibiotic therapy in the clinical infection group based on experience on the 14th day of treatment were 20% higher than these based on IL-8≥70pg/ml and or CRP>10mg/L,and the difference was statistically significant. So,the higher parts were the sections of excessive antibiotic therapy and reduced unnecessary antibiotic therapy. Conclusions1 Measurement of serum interleukin 8 in combination with C-reactive protein could diagnose neonatal infection early and reduce unnecessary antibiotic therapy with the best cut-off value of IL-8>70pg/ml and or CRP>10mg/L.2 The high-risk history and early clinical signs of neonatal infection were valuable to start precautionary antibiotic therapy,and if the course of antibiotic therapy was determined on experience that could lead to use antibiotics excessively.