Pan Hong-Wei, Li Wei, Li Rong-Guo, Li Yong, Zhang Yi, Sun En-Hua
Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China.
Department of Clinical Laboratory, Jinan Maternal and Child Care Hospital, Jinan, China.
Front Microbiol. 2018 Mar 20;9:481. doi: 10.3389/fmicb.2018.00481. eCollection 2018.
Rapid identification and determination of the antibiotic susceptibility profiles of the infectious agents in patients with bloodstream infections are critical steps in choosing an effective targeted antibiotic for treatment. However, there has been minimal effort focused on developing combined methods for the simultaneous direct identification and antibiotic susceptibility determination of bacteria in positive blood cultures. In this study, we constructed a lysis-centrifugation-wash procedure to prepare a bacterial pellet from positive blood cultures, which can be used directly for identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and antibiotic susceptibility testing by the Vitek 2 system. The method was evaluated using a total of 129 clinical bacteria-positive blood cultures. The whole sample preparation process could be completed in <15 min. The correct rate of direct MALDI-TOF MS identification was 96.49% for gram-negative bacteria and 97.22% for gram-positive bacteria. Vitek 2 antimicrobial susceptibility testing of gram-negative bacteria showed an agreement rate of antimicrobial categories of 96.89% with a minor error, major error, and very major error rate of 2.63, 0.24, and 0.24%, respectively. Category agreement of antimicrobials against gram-positive bacteria was 92.81%, with a minor error, major error, and very major error rate of 4.51, 1.22, and 1.46%, respectively. These results indicated that our direct antibiotic susceptibility analysis method worked well compared to the conventional culture-dependent laboratory method. Overall, this fast, easy, and accurate method can facilitate the direct identification and antibiotic susceptibility testing of bacteria in positive blood cultures.
快速鉴定和确定血流感染患者感染病原体的抗生素敏感性谱，是选择有效靶向抗生素进行治疗的关键步骤。然而，目前很少有人致力于开发联合方法，用于同时直接鉴定阳性血培养中的细菌并测定其抗生素敏感性。在本研究中，我们构建了一种裂解-离心-洗涤程序，用于从阳性血培养物中制备细菌沉淀，该沉淀可直接用于基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）鉴定和Vitek 2系统的抗生素敏感性测试。使用总共129份临床细菌阳性血培养物对该方法进行了评估。整个样品制备过程可在15分钟内完成。革兰氏阴性菌直接MALDI-TOF MS鉴定的正确率为96.49%，革兰氏阳性菌为97.22%。革兰氏阴性菌的Vitek 2抗菌药物敏感性测试显示，抗菌药物类别的符合率为96.89%，轻微错误率、主要错误率和非常主要错误率分别为2.63%、0.24%和0.24%。针对革兰氏阳性菌的抗菌药物类别符合率为92.81%，轻微错误率、主要错误率和非常主要错误率分别为4.51%、1.22%和1.46%。这些结果表明，与传统的依赖培养的实验室方法相比，我们的直接抗生素敏感性分析方法效果良好。总体而言，这种快速、简便且准确的方法有助于对阳性血培养中的细菌进行直接鉴定和抗生素敏感性测试。
