U.O.C. Laboratory Analysis Unit, A.O.U. "Policlinico-San Marco", Via S. Sofia 78, Catania, 95123, Italy.
Clinical Microbiology, Department of Biomedical and Biotechnological Sciences, Policlinico Hospital, University of Catania, Via Santa Sofia 97 Third floor, Est tower, Catania, 95124, Italy.
Ann Clin Microbiol Antimicrob. 2023 Aug 11;22(1):72. doi: 10.1186/s12941-023-00617-8.
Sepsis represents a time-sensitive disease requiring early therapeutical intervention to avoid adverse patient outcomes. Rapid microbiological diagnosis is essential to investigate sepsis aetiological agents. The FAST™ system (Qvella, ON, Canada) provides a concentrated microbial suspension, known as a Liquid Colony™ (LC), directly from positive blood samples (PBCs) in 30-40 min to perform rapid identification (ID) and antimicrobial susceptibility testing (AST).
Qvella's FAST™ System and FAST PBC Prep cartridges were tested on PBCs from the Policlinico Hospital of Catania during a six-month study. Two millilitres of PBC were converted into an LC for rapid ID and AST using Bruker Biotyper Sirius MALDI and BD Phoenix systems. Standard of care (SOC) methods were used as a reference, requiring 48-72 h. Agreement between the innovative technology and the standard method was calculated.
FAST System processing was performed on 100 monomicrobial PBCs. Median turnaround times from blood cultures flagging positive to ID and AST completion were 2 and 26 h respectively. Therefore, the LC procedure was 24 h faster than the median turnaround times for SOC methods. 100% ID identification concordance was observed across 48 Gram-negative bacteria, 42 Gram-positive bacteria and 11 yeast for the genus level. 78% of Gram-negative and 95% of Gram-positive bacteria were resistant to ≥ 2 antimicrobial agents, including 45% (15/33) carbapenem-resistant enteric Gram-negative bacteria and 90% (28/31) oxacillin-resistant staphylococci. An AST essential agreement of 100% was observed due to the absence of MIC discrepancies > 1-fold dilution. Categorical errors were not observed due to the absence of MIC categorization discordances. Yeast AST was not performed.
The Qvella FAST System produces an LC that reliably reflects the MALDI spectra and phenotypic antimicrobial susceptibility profile of microbial cells growing in the blood culture. Timely processing of PBCs with the Qvella FAST System enables sepsis diagnostic confirmation 1 day sooner than the standard methods. In line with these results, it is vital now to focus attention on establishing best practices for incorporating this strategic tool into the clinical microbiology laboratory workflow.
败血症是一种需要及时治疗的疾病，需要早期进行治疗干预，以避免患者出现不良结局。快速微生物诊断对于确定败血症的病因至关重要。FAST 系统（Qvella，ON，加拿大）可在 30-40 分钟内从阳性血培养物（PBC）中直接获得浓缩微生物悬液，称为液体集落（LC），用于快速鉴定（ID）和药敏试验（AST）。
在六个月的研究期间，我们在卡塔尼亚综合医院使用 Qvella 的 FAST 系统和 FAST PBC 制备试剂盒对 PBC 进行了测试。将两毫升 PBC 转化为 LC，用于快速 ID 和 AST，使用 Bruker Biotyper Sirius MALDI 和 BD Phoenix 系统。采用标准护理（SOC）方法作为参考，需要 48-72 小时。计算创新技术与标准方法的一致性。
对 100 份单微生物 PBC 进行了 FAST 系统处理。从血培养物阳性到 ID 和 AST 完成的中位周转时间分别为 2 小时和 26 小时。因此，LC 程序比 SOC 方法的中位周转时间快 24 小时。在 48 种革兰氏阴性菌、42 种革兰氏阳性菌和 11 种酵母属中，观察到 100%的 ID 鉴定一致性。革兰氏阴性菌的耐药率为 78%，革兰氏阳性菌的耐药率为 95%，包括 45%（15/33）耐碳青霉烯肠杆菌和 90%（28/31）耐苯唑西林葡萄球菌。由于 MIC 差异不超过 1 倍稀释，AST 一致性为 100%。由于没有 MIC 分类差异，没有观察到分类错误。未进行酵母 AST。
Qvella FAST 系统产生的 LC 能够可靠地反映血培养中微生物细胞的 MALDI 光谱和表型抗菌药物敏感性谱。使用 Qvella FAST 系统及时处理 PBC 可使败血症诊断确认提前 1 天，优于标准方法。根据这些结果，现在必须将注意力集中在建立将这一战略工具纳入临床微生物学实验室工作流程的最佳实践上。
