Necrotizing soft tissue infections (NSTI) are rapidly progressing and life-threatening conditions that require prompt diagnosis. However, differentiating NSTI from other non-necrotizing skin and soft tissue infections (SSTIs) remains challenging. We aimed to evaluate the diagnostic value of the biochemical analysis of soft tissue infectious fluid in distinguishing NSTIs from non-necrotizing SSTIs. This cohort study prospectively enrolled adult patients between May 2023 and April 2024, and retrospectively included patients from April 2019 to April 2023. Patients with a clinical suspicion of NSTI in the limbs who underwent successful ultrasound-guided aspiration to obtain soft tissue infectious fluid for biochemical analysis were evaluated and classified into the NSTI and non-necrotizing SSTI groups based on their final discharge diagnosis. Common extravascular body fluid (EBF) criteria were applied. Of the 72 patients who met the inclusion criteria, 10 patients with abscesses identified via ultrasound-guided aspiration were excluded. Based on discharge diagnoses, 39 and 23 patients were classified into the NSTI and non-necrotizing SSTI groups, respectively. Biochemical analysis revealed significantly higher albumin, lactate, lactate dehydrogenase (LDH), and total protein levels in the NSTI group than in the non-necrotizing SSTI group, and the NSTI group had significantly lower glucose levels and pH in soft tissue fluids. In the biochemical analysis, LDH demonstrated outstanding discrimination (area under the curve (AUC) = 0.955; p < 0.001) among the biochemical markers. Albumin (AUC = 0.884; p < 0.001), lactate (AUC = 0.891; p < 0.001), and total protein (AUC = 0.883; p < 0.001) levels also showed excellent discrimination. Glucose level (AUC = 0.774; p < 0.001) and pH (AUC = 0.780; p < 0.001) showed acceptable discrimination. When the EBF criteria were evaluated, the total scores of Light’s criteria (AUC = 0.925; p < 0.001), fluid-to-serum LDH ratio (AUC = 0.929; p < 0.001), and fluid-to-serum total protein ratio (AUC = 0.927; p < 0.001) demonstrated outstanding discrimination. Biochemical analysis and EBF criteria demonstrated diagnostic performances ranging from acceptable to outstanding for NSTI when analyzing soft tissue infectious fluid. These findings provide valuable diagnostic insights into the recognition of NSTI. Further research is required to validate these findings.

中文翻译：

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软组织感染液的生化分析及其在坏死性软组织感染中的诊断价值：一项为期 5 年的队列研究


坏死性软组织感染 （NSTI） 进展迅速，危及生命，需要及时诊断。然而，将 NSTI 与其他非坏死性皮肤和软组织感染 （SSTI） 区分开来仍然具有挑战性。我们旨在评估软组织感染液生化分析在区分 NSTI 和非坏死性 SSTI 中的诊断价值。该队列研究前瞻性地招募了 2023 年 5 月至 2024 年 4 月期间的成年患者，并回顾性纳入了 2019 年 4 月至 2023 年 4 月期间的患者。对临床怀疑肢体 NSTI 的患者，成功接受超声引导下抽吸以获取软组织感染液进行生化分析，根据其最终出院诊断进行评估并分为 NSTI 组和非坏死性 SSTI 组。应用常见的血管外体液 （EBF） 标准。在符合纳入标准的 72 例患者中，排除了 10 例通过超声引导下抽吸发现的脓肿患者。根据出院诊断，39 例和 23 例患者分别分为 NSTI 组和非坏死性 SSTI 组。生化分析显示，NSTI 组白蛋白、乳酸、乳酸脱氢酶 （LDH） 和总蛋白水平显著高于非坏死性 SSTI 组，NSTI 组软组织液中葡萄糖水平和 pH 值显著降低。在生化分析中，LDH 在生化标志物中表现出出色的区分力 （曲线下面积 （AUC） = 0.955;p < 0.001）。白蛋白 （AUC = 0.884;p < 0.001）、乳酸 （AUC = 0.891;p < 0.001） 和总蛋白 （AUC = 0.883;p < 0.001） 水平也显示出极好的区分力。血糖水平 （AUC = 0.774;p < 0.001） 和 pH 值 （AUC = 0.780;p < 0.001） 显示出可接受的区分度。当评估 EBF 标准时，Light 标准的总分 （AUC = 0.925;p < 0.001）、体液与血清 LDH 比值 （AUC = 0.929;p < 0.001） 和体液与血清总蛋白比值 （AUC = 0.927;p < 0.001） 表现出出色的区分力。生化分析和 EBF 标准表明，在分析软组织感染性液体时，NSTI 的诊断性能从可接受到优秀不等。这些发现为 NSTI 的识别提供了有价值的诊断见解。需要进一步的研究来验证这些发现。