Department of Laboratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, People's Republic of China.
National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, People's Republic of China.
Infection. 2024 Jun;52(3):1027-1039. doi: 10.1007/s15010-023-02157-x. Epub 2023 Dec 21.
Nosocomial bloodstream infections (nBSI) have emerged as a clinical concern for physicians treating COVID-19 patients. In this study, we aimed to evaluate the effectiveness of a multiplex ddPCR in detecting bacterial pathogens in the blood of COVID-19 critically ill patients.
This prospective diagnostic study included RT-PCR-confirmed COVID-19 patients admitted to our hospital from December 2022 to February 2023. A multiplex ddPCR assay was used to detect common bacterial pathogens and AMR genes in blood samples of the patients, along with antimicrobial susceptibility testing (AST). The diagnostic performance of the ddPCR assay was evaluated by comparing the results with those obtained through blood culture and clinical diagnosis. Additionally, the ability of ddPCR in detecting bacterial resistance was compared with the AST results.
Of the 200 blood samples collected from 184 patients, 45 (22.5%) were positive using blood culture, while 113 (56.5%) were positive for bacterial targets using the ddPCR assay. The ddPCR assay outperformed blood culture in pathogen detection rate, mixed infection detection rate, and fungal detection rate. Acinetobacter baumannii and Klebsiella pneumoniae were the most commonly detected pathogens in COVID-19 critically ill patients, followed by Enterococcus and Streptococcus. Compared to blood culture, ddPCR achieved a sensitivity of 75.5%, specificity of 51.0%, PPV of 30.9%, and NPV of 87.8%, respectively. However, there were significant differences in sensitivity among different bacterial species, where Gram-negative bacteria have the highest sensitivity of 90.3%. When evaluated on the ground of clinical diagnosis, the sensitivity, specificity, PPV and NPV of ddPCR were 78.1%, 90.5%, 94.7%, and 65.5%, respectively. In addition, the ddPCR assay detected 23 cases of bla, which shown a better consistent with clinical test results than other detected AMR genes. Compared to bla, there were few other AMR genes detected, indicating that the application of other AMR gene detection in the COVID-19 critically ill patients was limited.
The multiplex ddPCR assay had a significantly higher pathogen detection positivity than the blood culture, which could be an effective diagnostic tool for BSIs in COVID-19 patients and to improve patient outcomes and reduce the burden of sepsis on the healthcare system, though there is room for optimization of the panels used.- Adjusting the targets to include E. faecalis and E. faecium as well as Candida albicans and Candida glabrata could improve the ddPCR' s effectiveness. However, further research is needed to explore the potential of ddPCR in predicting bacterial resistance through AMR gene detection.
医院获得性血流感染（nosocomial bloodstream infections，nBSI）已成为治疗 COVID-19 患者的医生关注的临床问题。在这项研究中，我们旨在评估多重 ddPCR 检测 COVID-19 危重症患者血液中细菌病原体的有效性。
这是一项前瞻性诊断研究，纳入了 2022 年 12 月至 2023 年 2 月期间我院收治的经 RT-PCR 确诊的 COVID-19 患者。采用多重 ddPCR 法检测患者血液中的常见细菌病原体和 AMR 基因，并进行抗菌药物敏感性检测（AST）。通过与血培养和临床诊断结果进行比较，评估 ddPCR 检测的诊断性能。此外，还比较了 ddPCR 检测细菌耐药性的能力与 AST 结果。
从 184 例患者的 200 份血样中，45 份（22.5%）经血培养阳性，113 份（56.5%）经 ddPCR 检测到细菌靶标阳性。ddPCR 检测在病原体检测率、混合感染检测率和真菌检测率方面均优于血培养。鲍曼不动杆菌和肺炎克雷伯菌是 COVID-19 危重症患者中最常见的病原体，其次是肠球菌和链球菌。与血培养相比，ddPCR 的敏感性分别为 75.5%、特异性为 51.0%、PPV 为 30.9%和 NPV 为 87.8%。然而，不同细菌种类的敏感性存在显著差异，革兰氏阴性菌的敏感性最高，为 90.3%。当基于临床诊断进行评估时，ddPCR 的敏感性、特异性、PPV 和 NPV 分别为 78.1%、90.5%、94.7%和 65.5%。此外，ddPCR 检测到 23 例 bla，与临床检测结果的一致性优于其他检测的 AMR 基因。与 bla 相比，其他 AMR 基因的检测数量较少，表明在 COVID-19 危重症患者中，其他 AMR 基因的检测应用有限。
多重 ddPCR 检测的病原体检测阳性率明显高于血培养，可能是 COVID-19 患者菌血症的有效诊断工具，有助于改善患者预后并减轻脓毒症对医疗系统的负担，但用于检测的panel 仍有优化空间。通过调整靶标，包括屎肠球菌和屎肠球菌以及白色念珠菌和光滑念珠菌，可以提高 ddPCR 的效果。然而，需要进一步研究探索通过 AMR 基因检测预测细菌耐药性的 ddPCR 的潜力。
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