摘要
早期病原学精准诊断是改善感染性胰腺坏死(IPN)患者预后的突破口之一,但目前临床上缺乏早期精准识别IPN的高效方法。本研究探讨基于宏基因捕获法(MetaCAP)的二代测序技术在IPN病原学诊断中的应用价值。
采用前瞻性研究方法,选取2024年1月—7月中南大学湘雅医院29例疑似急性坏死性胰腺炎患者进行血MetaCAP检测和常规病原学培养。将胰周积液病原学培养结果作为金标准,比较两种检测方法的诊断效能。
由于3例未获胰周积液培养结果,纳入最终分析的病例总数为26例。全组病死率为23.1%(6/26)。住院期间,确诊IPN的病例为9例(34.6%)。MetaCAP诊断IPN的敏感度和阴性预测值均明显高于常规病原学培养(77.8% vs. 11.1%,P=0.031;86.7% vs. 65.2%,P=0.032),而两种方法的特异度(76.5% vs. 88.2%,P=0.689)和阳性预测值(63.6% vs. 33.3%,P=0.347)差异无统计学意义。MetaCAP的平均检测耗时33(20~49)h,微生物培养耗时125(45~142)h,差异有统计学意义(P<0.001)。血MetaCAP检测的平均费用为2 500元/例,但MetaCAP检测仅占平均住院费用的1.19%。
关键词
感染性胰腺坏死(infected pancreatic necrosis,IPN)是急性胰腺炎的严重并发症,病死率可高达30%,是急性胰腺炎的主要死因之
2024年1月—2024年7月间中南大学湘雅医院连续收治的疑似感染的ANP患者29例。符合疑似感染的ANP病例需满足以下条件:⑴ 符合急性胰腺炎诊断标准;⑵ 增强CT扫描显示胰腺和(或)胰周组织坏死;⑶ 病程中体温≥38.5 ℃;⑷ 未接受腹腔及腹膜后侵入性外科干预。有3例患者在外科干预前因多器官功能衰竭死亡,未能获得胰周引流液病原体培养结果,无法确诊胰周感染,因此被排除,最终纳入分析的病例数为26例。IPN诊断标准为首次外科干预获取胰腺或胰周坏死组织或积液经细菌或真菌培养阳性

图1 病例入组流程图
Figure 1 Flowchart of case enrollment
对于符合纳入标准的ANP患者,当在病程中体温达到或超过38.5 ℃时,采集双上肢静脉血各10 mL并分别放入需氧和厌氧血培养瓶中进行微生物培养。同时,从上肢静脉采集10 mL血液至游离核酸样本保存管中用于MetaCAP检验。
MetaCAP检验步骤为:将静脉血放置于游离核酸样本保存管中,并将采集的样本保存在4 ℃冰箱内。在24 h内,专人将样本送至金域医学检验实验室,进行样本处理、核酸提取、文库构建及MetaCAP测序。MetaCAP样本的收集、保存和运输均严格依照标准化规范进行。测序与数据处理按照金域基因Illumina平台的标准流程进行,通过比对获得匹配病原体的序列数,并根据序列数的高低、覆盖度及相对丰度等指标最终出具检测报告。若检出细菌或真菌,则报告为阳性结果。
所有病例均按照国内外最新指南进行规范化治
采用SPSS 26.0软件作为数据统计分析工具。根据数据类型和分布特点,计量资料以中位数(范围)[M(范围)]表示;计数资料以例数(百分比)[n(%)]表示,组间阳性率比较采用
26例患者中,男22例,女4例;中位年龄49.5(18~67)岁;中位住院时间31.5(6~102)d。病因包括高脂血症性14例(53.8%)、胆源性8例(30.7%)、酒精性2例(7.6%),不明原因2例(7.6%)。根据2012年亚特兰大分
MetaCAP的敏感度为77.8%(7/9),特异度为76.5%(13/17),阳性预测值为63.6%,阴性预测值为86.7%。4例假阳性结果中,其中1例检出德氏根霉菌和热带念珠菌,序列数分别为194和2,补充检测GM试验为阳性。而血培养的敏感度为11.1%(1/9),特异度为88.2%(15/17),阳性预测值为33.3%,阴性预测值为65.2%。1例假阳性检测出头状葡萄球菌,另1例假阳性检测出人葡萄球菌。两种方法在诊断IPN的敏感度和阴性预测值方面差异有统计学意义(敏感度:P=0.031,阴性预测值:P=0.032),而在特异度和阳性预测值方面则差异无统计学意义(特异度:P=0.689,阳性预测值:P=0.347)(

图2 外周血MetaCAP和培养诊断IPN的敏感度与特异度对比
Figure 2 Comparison of sensitivity and specificity of peripheral blood MetaCAP and culture in diagnosing IPN
9例IPN患者的血MetaCAP有2例为阴性,其它7例病原学相符率为100%。7例相符病例中,5例MetaCAP病原学结果完全覆盖培养病原学结果,2例MetaCAP病原学结果与培养病原学结果存在交集。4例IPN患者的血MetaCAP检测出耐药基因,分别为KPC-77:30、OXA-23:115、KPC-2:10264和OXA:84,均与相应的胰周积液培养出的耐药菌表型相符(

图3 外周血MetaCAP病原学和耐药结果与胰周积液培养结果的相符性
Figure 3 The concordance of peripheral blood MetaCAP pathogen detection and drug resistance results with peritoneal fluid culture results
由于IPN的治疗难度大、病死率高、治疗费用昂贵,早期识别并预防IPN的发生至关重要。细针穿刺术(fine-needle aspiration,FNA)获取胰周培养结果被认为是诊断IPN的金标准,但目前主流治疗策略是延迟干预。早期进行穿刺可能导致脏器损伤、出血以及无菌性胰腺组织继发感染的风险,甚至可能促使感染扩散。因此,目前并不建议常规早期使用FNA来确诊IP
MetaCAP技术是在mNGS基础之上,使用百万探针捕获技术,可检测不同样本类型中微生物组的高通量测序方法。但目前仍没有应用于IPN的研究报道。本研究首次应用MetaCAP技术探讨IPN病原学诊断中的应用。与传统血培养相比,MetaCAP展现了其在敏感度、耐药预测、检测速度和成本效益等方面的潜在优势。类似于本团队前期研究显示mNGS的优异检验效
大量研
同时,本研究结果显示,MetaCAP技术不仅在病原微生物的早期识别能发挥作用,在防治耐药菌上也能起到重要的作用。随着抗菌药物在临床得到广泛应用,IPN多重耐药菌感染具有较高发生率,与之相关的外科干预次数增多、ICU住院时间和总住院时间明显延长、住院费用增加,且病死率也明显增
综上所述,MetaCAP技术在IPN的病原学诊断中展现出较短的检测耗时、优良的检验效能及卫生经济学价值。与传统血培养相比,MetaCAP在敏感度、阴性预测值和耐药检测方面具有明显优势,能够为临床医生提供更及时的诊断信息,有助于优化抗菌药物的使用和避免不必要的外科干预,进而减轻患者的经济负担。但目前MetaCAP属于新兴技术,在胰腺炎的治疗领域目前仍没有相应的临床研究报道,也没有统一的报告解释标准,缺乏与传统诊断方法较大规模的比较验证,检测结果的临床解释存在一定争议。因此,临床上需进一步扩大样本量对MetaCAP检测结果进行解析,探讨其病原学检测的效能,使MetaCAP技术能真正在IPN的早期诊断中发挥其精准快速的优点。
作者贡献声明
刘柏岐负责实验设计、病例收集、数据统计分析、文章撰写;李嘉荣负责实验设计、数据统计分析、数据整理;洪晓悦、林嘉晏负责数据整理;孙泽芳、宁彩虹负责病例收集;陈璐、朱帅负责研究指导;申鼎成负责研究指导、论文审阅、经费支持;余艳负责研究指导、技术支持;黄耿文负责研究指导、论文审阅、经费支持。
利益冲突
所有作者均声明不存在利益冲突。
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