Background: For quick detection or exclusion of neonatal early-onset bacterial infection (EOBI) or late-onset bacterial infection (LOBI), interleukin (IL)-6 is used. Its clinical use is sometimes limited due to prolonged recall times. Therefore, an IL-6 bedside test was established. Objective: To compare the diagnostic value of plasma IL-6 and an IL-6 bedside test at the time of clinical suspicion in the course of EOBI and LOBI. Methods: Eighteen term (mean gestational age 40.2 weeks, SD 1.3) and 88 preterm (mean gestational age 30.1 weeks, SD 4.2) neonates with clinical and serological signs of bacterial infection were analysed. Eight had an EOBI, and 24 had a LOBI, of whom 13 were blood culture positive. Twelve term and 62 preterm neonates with risk factors but without proven EOBI/LOBI served as a non-infected group. Results: At the time of clinical suspicion, the sensitivity of the IL-6 bedside test in comparison to plasma IL-6 was 69 versus 75% (p = 0.7744, McNemar’s test), and specificity was 77 versus 81% (p = 0.6476, McNemar’s test; cutoff level 50 ng/l). For LOBI, both the sensitivity (75%) and specificity (82%) of the bedside test exceeded values calculated for EOBI (sensitivity 50%, specificity 75%). Conclusion: No significant difference between the bedside and established plasma IL-6 test was detected for LOBI. For detection of EOBI, the bedside test was not sensitive enough. Larger studies are needed to verify our findings before IL-6 bedside tests can be recommended routinely.

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