Verroken Alexia, Hajji Chaima, Bressant Florian, Couvreur Jonathan, Anantharajah Ahalieyah, Rodriguez-Villalobos Hector
Department of Microbiology, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.
Front Microbiol. 2022 Sep 15;13:982650. doi: 10.3389/fmicb.2022.982650. eCollection 2022.
As time to appropriate antimicrobial therapy is major to reduce sepsis mortality, there is great interest in the development of tools for direct identification (ID) and antimicrobial susceptibility testing (AST) of positive blood cultures (PBC). Very recently, the FAST™ System (Qvella) has been developed to isolate and concentrate microorganisms directly from PBCs, resulting in the recovery of a Liquid Colony™ (LC) within 30 min. The LC can be used as equivalent of an overnight subcultured colony for downstream testing. We aimed to evaluate the performances of the FAST™ System and FAST-PBC Prep™ cartridges by testing the resulting LC for direct ID, AST and rapid resistance detection.
Prospectively, FAST™ System testing was carried out on each patient's first PBC with a monomicrobial Gram-stain result. In the second arm of the study, FAST™ System testing was carried out on blood cultures spiked with multidrug-resistant bacteria. Downstream testing using the LC included MALDI-TOF MS ID with the Bruker Biotyper smart system, rapid resistance detection testing including the Abbott Diagnostics Clearview™ PBP2a SA Culture Colony Test (PBP2a) and the Bio-Rad βLACTA™ Test (βLT). AST was performed using the Becton Dickinson Phoenix™ System or by Bio-Rad disk diffusion using filter paper disk following EUCAST 2020 breakpoint criteria.
FAST™ System testing was completed on 198 prospective PBCs and 80 spiked blood cultures. After exclusion of polymicrobial blood cultures, performance evaluation compared with standard of care results was carried out on 266 PBCs. Concordant, erroneous and no ID results included 238/266 (89.5%), 1/266 (0.4%), 27/266 (10.2%) PBCs, respectively. Sensitivity and specificity for PBP2a were 100% (10/10) and 75% (15/20), respectively. Sensitivity and specificity for βLT were 95.8% (23/24) and 100% (42/42), respectively. Categorical agreement for all 160 tested strains was 98% (2299/2346) with 1.2% (8/657) very major errors and 0.7% (10/1347) major errors.
FAST™ System testing is a reliable approach for direct downstream testing of PBCs including MALDI-TOF MS ID, BD Phoenix™ and Bio-Rad disk diffusion AST as well as rapid resistance testing assays. Next steps include optimal integration of the FAST™ System in the PBC workflow with a view toward clinical studies.
由于及时给予恰当的抗菌治疗对于降低脓毒症死亡率至关重要，因此人们对开发用于直接鉴定（ID）和检测阳性血培养物（PBC）的抗菌药敏试验（AST）的工具有着浓厚兴趣。最近，已经开发出FAST™系统（Qvella），用于直接从PBC中分离和浓缩微生物，从而在30分钟内获得液体菌落™（LC）。该LC可作为过夜传代培养菌落用于下游检测。我们旨在通过检测所得LC进行直接ID、AST和快速耐药性检测，来评估FAST™系统和FAST-PBC Prep™试剂盒的性能。
前瞻性地，对每位患者首次革兰氏染色结果为单一微生物的PBC进行FAST™系统检测。在研究的第二组中，对添加了多重耐药菌的血培养物进行FAST™系统检测。使用LC进行的下游检测包括使用布鲁克Biotyper智能系统进行基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）ID、快速耐药性检测试验，包括雅培诊断Clearview™ PBP2a SA培养菌落试验（PBP2a）和伯乐βLACTA™试验（βLT）。使用贝克曼库尔特Phoenix™系统进行AST，或按照2020年欧洲药敏试验委员会（EUCAST）断点标准，使用滤纸片通过伯乐纸片扩散法进行AST。
对198份前瞻性PBC和80份添加菌的血培养物完成了FAST™系统检测。排除多微生物血培养物后，对266份PBC与标准治疗结果进行了性能评估比较。一致、错误和无ID结果分别包括238/266（89.5%）、1/266（0.4%）、27/266（10.2%）份PBC。PBP2a的敏感性和特异性分别为100%（10/10）和75%（15/20）。βLT的敏感性和特异性分别为95.8%（23/24）和100%（42/42）。对所有160株受试菌株的分类一致性为98%（2299/2346），有1.2%（8/657）的极重大错误和0.7%（10/1347）的重大错误。
FAST™系统检测是一种可靠的方法，可用于PBC的直接下游检测，包括MALDI-TOF MS ID、BD Phoenix™和伯乐纸片扩散AST以及快速耐药性检测试验。下一步包括将FAST™系统最佳整合到PBC工作流程中，以开展临床研究。
