Haddad Gabriel, Bellali Sara, Takakura Tatsuki, Fontanini Anthony, Ominami Yusuke, Bou Khalil Jacques, Raoult Didier
Institut Hospitalo-Universitaire Méditerranée Infection 19-21 Boulevard Jean Moulin, 13005 Marseille, France.
Aix-Marseille Université, IRD, APHM, MEPHI, 27 Boulevard Jean Moulin, 13005 Marseille, France.
Microorganisms. 2021 May 28;9(6):1170. doi: 10.3390/microorganisms9061170.
Blood culture is currently the most commonly used method for diagnosing sepsis and bloodstream infections. However, the long turn-around-time to achieve microbe identification remains a major concern for clinical microbiology laboratories. Gram staining for preliminary identification remains the gold standard. We developed a new rapid strategy using a tabletop scanning electron microscope (SEM) and compared its performance with Gram staining for the detection of micro-organisms and preliminary identification directly from blood cultures. We first optimised the sample preparation for twelve samples simultaneously, saving time on imaging. In this work, SEM proved its ability to identify bacteria and yeasts in morphotypes up to the genus level in some cases. We blindly tested 1075 blood cultures and compared our results to the Gram staining preliminary identification, with MALDI-TOF/MS as a reference. This method presents major advantages such as a fast microbe identification, within an hour of the blood culture being detected positive, low preparation costs, and data traceability. This SEM identification strategy can be developed into an automated assay from the sample preparation, micrograph acquisition, and identification process. This strategy could revolutionise urgent microbiological diagnosis of infectious diseases.
血培养是目前诊断败血症和血流感染最常用的方法。然而,实现微生物鉴定的周转时间较长,仍然是临床微生物实验室主要关注的问题。革兰氏染色进行初步鉴定仍是金标准。我们开发了一种使用台式扫描电子显微镜(SEM)的新型快速策略,并将其与革兰氏染色在直接从血培养物中检测微生物和进行初步鉴定方面的性能进行了比较。我们首先同时优化了12个样本的制备,节省了成像时间。在这项工作中,扫描电子显微镜证明了在某些情况下能够将细菌和酵母鉴定到属水平的形态类型。我们对1075份血培养物进行了盲测,并将我们的结果与革兰氏染色初步鉴定结果进行比较,以基质辅助激光解吸电离飞行时间质谱(MALDI-TOF/MS)作为参考。该方法具有诸多主要优点,如在血培养检测呈阳性后一小时内即可快速鉴定微生物、制备成本低以及数据可追溯性强。这种扫描电子显微镜鉴定策略可以从样本制备、显微图像采集和鉴定过程发展为自动化检测方法。该策略可能会彻底改变传染病的紧急微生物诊断。