【摘要】 目的 血流感染的死亡率和致残率较高，每年的死亡病例数可达800万，准确及时的病原学诊断至关重要。本研究的目的是评估液滴数字PCR（droplet digital PCR，ddPCR）在诊断血流感染的应用价值。方法 作为一项前瞻性研究，2021-2023年收集了55例疑似血流感染患者的血浆，将液滴数字PCR检测（3小时左右）与传统的血培养（blood culture，BC；最快48小时左右）结果进行比较。结果 ddPCR敏感性和阴性预测值较高，达到69.2%和90%，阳性率为70%，显著高于血培养。在ddPCR+/BC+组中，ddPCR检测出的病原菌的基因拷贝数与降钙素原、C反应蛋白、白细胞呈同步变化趋势；不过ddPCR阳性与血浆中的炎性因子降钙素原、C反应蛋白、白细胞没有显著相关性。通过药敏试验发现了6株碳青霉烯耐药的肺炎克雷伯菌，ddPCR全部从相应标本检测出丝氨酸酶（blaKPC）或者金属酶（blaNDM和blaIMP）；分离出3株耐甲氧西林葡萄球菌的标本亦全部检测出mecA基因，ddPCR还从未培养出细菌的9份标本中检出耐药基因。结论 液滴数字PCR是一种快速的病原体的检测手段，可作为传统血培养的附加补充，与临床患者的症状相结合，可以快速诊断可疑的血流感染病例，同时对耐药基因的检测亦有潜在的优势。

【Abstract】Purposes Bloodstream infection (BSI) has a high mortality and disability rate, and accurate and timely pathogen diagnosis is crucial. Our aim is to evaluate the value of droplet digital PCR (ddPCR) in diagnosing bloodstream infections. Methods We conducted a prospective study, collecting 55 patients suspected of bloodstream infection and comparing droplet digital PCR detection (approximately 3 hours) with traditional blood culture (BC, at least 48 hours). Results The sensitivity and negative predictive value of ddPCR were high, and the positive rate was significantly higher than that of blood culture; It was not significantly correlated with the inflammatory factors procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBC) in plasma; However, in the ddPCR+/BC+ group, the number of gene copy of pathogenic bacteria detected by ddPCR showed a synchronous trend with PCT, CRP, and WBC. In addition, all the six samples with carbapenem-resistant Klebsiella pneumoniae isolates identified through antimicrobial susceptibility testing were also detected by ddPCR, with serinase (blaKPC) or metalloenzymes (blaNDM and blaIMP). The mecA gene was also detected in all the three samples with methicillin-resistant Staphylococcus isolates. Moreover, ddPCR detected antimicrobial resistance genes in other nine culture-negative samples. Conclusion Droplet digital PCR is a rapid pathogen-detecting method that can be supplementary to traditional blood culture. When combined with clinical symptoms, ddPCR can be used to quickly diagnose patients with suspected bloodstream infections. At the same time, it also has potential advantages in detecting antimicrobial resistance genes.