Introduction. Contamination of specimens and overuse of broad spectrum antibiotics contribute to false positives and false negatives, respectively. Therefore, useful and applicable biomarkers of bacteremia are still required. Hypothesis/Gap Statement. IL-6 can be used as a serum biomarker to discriminate among bacterial infections and fungal infections in febrile patients with a bloodstream infection. Aim. We aimed to evaluate the diagnostic efficiency of neutrophil/lymphocyte ratio (NLR), procalcitonin (PCT) and interleukin-6 (IL-6) in discriminating Gram-negative (G−) bacteria from Gram-positive (G+) bacteria and fungi in febrile patients. Methodology. A total of 567 patients with fever were evaluated. Serum levels of IL-6, PCT, NLR and CRP were compared among a G− group (n=188), a G+ group (n=168), a fungal group (n=38) and a culture negative group (n=173). Sensitivity, specificity, Yuden’s index and area under the Receiver operating characteristic (ROC) curve (AUC) were obtained to analyse the diagnostic abilities of these biomarkers in discriminating bloodstream infection caused by different pathogens. Results. Serum IL-6 and PCT in the G− group increased significantly when compared with both the G+ group and fungal group (P <0.05). AUC of IL-6 (0.767, 95 % CI:0.725–0.805) is higher than AUC of PCT (0.751, 95 % CI:0.708–0.796) in discriminating the G− group from G+ group. When discriminating the G− group from fungal group, the AUC of IL-6 (0.695, 95 % CI:0.651–0.747) with a cut-off value of 464.3 pg ml−1 was also higher than the AUC of PCT (0.630, 95 % CI:0.585–0.688) with a cut-off value of 0.68 ng ml−1. Additionally, AUC of NLR (0.685, 95 % CI:0.646–0.727) in discriminating the fungal group from G+ group at the cut-off value of 9.03, was higher than AUC of IL-6, PCT and CRP. Conclusion. This study suggests that IL-6 could be used as a serum biomarker to discriminate among bacterial infections and fungal infections in febrile patients with a bloodstream infection. In addition, NLR is valuable to discriminate fungal infections from Gram-positive infections in febrile patients with a bloodstream infection.

中文翻译：

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区分发热患者革兰氏阴性、革兰氏阳性和真菌感染的血清生物标志物

介绍。标本的污染和广谱抗生素的过度使用分别导致假阳性和假阴性。因此，仍然需要有用和适用的菌血症生物标志物。假设/差距陈述。IL-6 可用作血清生物标志物，以区分伴有血流感染的发热患者的细菌感染和真菌感染。目标。我们旨在评估中性粒细胞/淋巴细胞比值 (NLR)、降钙素原 (PCT) 和白细胞介素 6 (IL-6) 在区分革兰氏阴性 (G - ) 细菌与革兰氏阳性 (G + ) 细菌和真菌方面的诊断效率在发热患者中。方法。共评估了 567 名发热患者。IL-6的血清水平，PCT，NLR和CRP中A G进行比较-组（ñ = 188），G的+组（Ñ = 168），真菌组（Ñ = 38）和培养阴性组（Ñ =173）。获得敏感性、特异性、Yuden's指数和接受者操作特征（ROC）曲线下面积（AUC）以分析这些生物标志物在区分不同病原体引起的血流感染方面的诊断能力。结果。血清IL-6和PCT在G -当与两个克，比组显著增加+组和真菌组（P<0.05）。在区分 G -组和 G +组方面，IL-6 的 AUC（0.767，95% CI：0.725-0.805）高于 PCT 的 AUC（0.751，95% CI：0.708-0.796）。当区分 G -组和真菌组时，截断值为 464.3 pg ml -1的 IL-6 的 AUC（0.695，95 % CI：0.651–0.747）也高于 PCT 的 AUC（0.630， 95 % CI：0.585–0.688），临界值为 0.68 ng ml -1。此外，NLR 的 AUC（0.685，95% CI：0.646–0.727）在以 9.03 的临界值区分真菌组与 G +组时，高于 IL-6、PCT 和 CRP 的 AUC。结论。这项研究表明，IL-6 可用作血清生物标志物，以区分伴有血流感染的发热患者的细菌感染和真菌感染。此外，NLR 可用于区分血流感染发热患者的真菌感染和革兰氏阳性菌感染。