Department of Laboratory Medicine, College of Medicine, Korea University, Seoul, Korea.
Department of Laboratory Medicine, College of Medicine, Chosun University, Gwangju, Korea.
Eur J Clin Microbiol Infect Dis. 2023 Jun;42(6):691-700. doi: 10.1007/s10096-023-04592-y. Epub 2023 Apr 3.
This study aimed to assess the performance of our in-house method for rapid direct bacterial identification (ID) and antimicrobial susceptibility testing (AST) using a positive blood culture (BC) broth. For Gram-negative bacteria, 4 mL of BC broth was aspirated and passed through a Sartorius Minisart syringe filter with a pore size of 5 µm. The filtrate was then centrifuged and washed. A small volume of the pellet was used for ID, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and for AST, using automated broth microdilution. For Gram-positive cocci, 4 mL of BC broth was passed through the Minisart syringe filter. Then, 4 mL of sterile distilled water was injected in the direction opposite to that of the filtration to collect the bacterial residue trapped in the filter. Compared with the conventional method performed with pure colonies on agar plates, 94.0% (234/249) were correctly identified using the in-house method, with rates of 91.4% (127/139) and 97.3% (107/110) for Gram-positive and Gram-negative isolates, respectively. Of 234 correctly identified isolates, 230 were assessed by AST. Categorical agreement and essential agreement were 93.3% and 94.5%, respectively, with a minor error rate of 3.8%, a major error rate of 3.4%, and a very major error rate of 1.6%. Our in-house preparation method showed good performance in rapid direct ID and AST using positive BC broths compared to the conventional method. This simple method can shorten the conventional turnaround time for ID and AST by at least 1 day, potentially contributing to better patient management.
本研究旨在评估我们使用阳性血培养肉汤进行快速直接细菌鉴定 (ID) 和抗菌药物敏感性测试 (AST) 的内部方法的性能。对于革兰氏阴性菌，吸取 4 mL 的 BC 肉汤并通过 Sartorius Minisart 注射器过滤器进行过滤，该过滤器的孔径为 5 µm。然后将滤液离心并洗涤。使用基质辅助激光解吸/电离飞行时间质谱法对一小部分沉淀进行 ID，使用自动肉汤微量稀释法进行 AST。对于革兰氏阳性球菌，将 4 mL 的 BC 肉汤通过 Minisart 注射器过滤器。然后，向相反方向注入 4 mL 无菌蒸馏水，以收集被困在过滤器中的细菌残渣。与使用琼脂平板上的纯菌落进行的常规方法相比，使用内部方法正确鉴定了 94.0%（234/249）的菌株，革兰氏阳性和革兰氏阴性分离株的鉴定率分别为 91.4%（127/139）和 97.3%（107/110）。在 234 株正确鉴定的分离株中，有 230 株进行了 AST 评估。分类一致性和基本一致性分别为 93.3%和 94.5%，错误率为 3.8%，主要错误率为 3.4%，非常主要错误率为 1.6%。与常规方法相比，我们的内部制备方法在使用阳性 BC 肉汤进行快速直接 ID 和 AST 方面表现出良好的性能。这种简单的方法可以将 ID 和 AST 的常规周转时间至少缩短 1 天，从而有助于更好地管理患者。
