微滴数字PCR在重症急性胰腺炎疑似血流感染病原学诊断中的应用

Application of droplet digital PCR in etiological diagnosis of severe acute pancreatitis patients with suspected bloodstream infection

摘要:

目的 探讨微滴数字聚合酶链反应(ddPCR)在重症急性胰腺炎(SAP)合并疑似血流感染(BSI)病原学诊断中的价值。 方法 选取2022年7—9月某院重症医学科收治的SAP患者, 在疑似BSI发作时同步采集静脉血进行ddPCR检测和血培养(BC)及药敏试验(AST), 记录两种检测方法的耗时, 比较ddPCR与BC的检测结果, 计算ddPCR的病原学诊断效能, 并探讨ddPCR检测病原菌载量值与感染指标水平的相关性。 结果 共纳入22例患者, 采集52份静脉血标本进行检测, BC阳性17份(32.7%), 检出病原体29株; ddPCR阳性41份(78.8%), 检测出病原体73株。ddPCR耗时低于BC[(0.16±0.03)d VS (5.92±1.20)d, P＜0.001]。在ddPCR检测范围内, 以BC为金标准, ddPCR检测的灵敏度和特异度分别为80.0%、28.6%;联合检测前1周内非血标本微生物证据综合判定BSI, ddPCR检测的灵敏度和特异度分别提高至91.9%、76.9%。ddPCR耐药基因检测中, 19份检出bla_KPC, 9份检出bla_NDM/IMP, 6份检出VanA/VanM, 5份检出mecA。相关性分析显示病原菌载量值与C反应蛋白、降钙素原水平呈正相关(r分别为0.347、0.414, 均P＜0.05)。 结论 ddPCR作为一种辅助BC诊断BSI的检测方法具有灵敏度高、耗时低等优势, 值得进一步探讨其在临床中的应用。

Abstract:

Objective To explore the value of droplet digital polymerase chain reaction (ddPCR) in the etiological diagnosis of severe acute pancreatitis (SAP) patients with suspected bloodstream infection (BSI). Methods SAP patients admitted to the department of critical care medicine in a hospital July to September 2022 were enrolled. When BSI was suspected, venous blood was collected for both ddPCR detection and blood culture (BC) with antimicrobial susceptibility testing (AST) simultaneously. The time required for two detection methods was recorded, and the detection results of ddPCR and BC were compared. The etiological diagnostic efficacy of ddPCR was calculated, and the correlation between the value of pathogen load detected by ddPCR and the level of infection parameters was explored. Results A total of 22 patients were included in the analysis, and 52 venous blood specimens were collec-ted for detection. BC revealed 17 positive specimens (32.7%) and 29 pathogenic strains, while ddPCR showed 41 positive specimens (78.8%) and 73 pathogenic strains. Detection time required for ddPCR was significantly lower than that of BC ([0.16±0.03] days vs [5.92±1.20] days, P<0.001). Within the detection range of ddPCR and taking BC results as the gold standard, the sensitivity and specificity of ddPCR were 80.0% and 28.6%, respectively. With the combined assessment of BSI based on non-blood specimen microbial evidence within a week, the sensitivity and specificity of ddPCR detection increased to 91.9% and 76.9%, respectively. ddPCR detected resistance genes of bla_KPC, bla_NDM/IMP, VanA/VanM, and mecA from 19, 9, 6, and 5 specimens, respectively. Correlation analysis showed a positive correlation between pathogen load and levels of C-reactive protein as well as procalcitonin (r=0.347, 0.414, P<0.05). Conclusion As a supplementary detection method for BC in BSI diagnosis, ddPCR has the advantages of higher sensitivity and shorter detection time, and is worthy of further exploration in clinical application.