Bonaiuto Chiara, Baccani Ilaria, Chilleri Chiara, Antonelli Alberto, Giani Tommaso, Rossolini Gian Maria
Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy.
Clinical Microbiology and Virology Unit, Careggi University Hospital, 50134 Florence, Italy.
Diagnostics (Basel). 2023 May 25;13(11):1849. doi: 10.3390/diagnostics13111849.
the aim of this study was to evaluate the performance of the Liquid Colony™ (LC) generated directly from positive blood cultures (PBCs) by the FAST System (Qvella, Richmond Hill, ON, Canada) for rapid identification (ID) and antimicrobial susceptibility testing (AST) compared with the standard of care (SOC) workflow.
Anonymized PBCs were processed in parallel by the FAST System and FAST PBC Prep cartridge (35 min runtime) and SOC. ID was performed by MALDI-ToF mass spectrometry (Bruker, Billerica, MA, USA). AST was performed by reference broth microdilution (Merlin Diagnostika, Bornheim, Germany). Carbapenemase detection was carried out with the lateral flow immunochromatographic assay (LFIA) RESIST-5 O.O.K.N.V. (Coris, Gembloux, Belgium). Polymicrobial PBCs and samples containing yeast were excluded.
241 PBCs were evaluated. ID results showed 100% genus-level concordance and 97.8% species-level concordance between LC and SOC. The AST results for Gram-negative bacteria showed a categorical agreement (CA) of 99.1% (1578/1593), with minor error (mE), major error (ME), and very major error (VME) rates of 0.6% (10/1593), 0.3% (3/1122), and 0.4% (2/471), respectively. The results from Gram-positive bacteria showed a CA of 99.6% (1655/1662), with mE, ME, and VME rates of 0.3% (5/1662), 0.2% (2/1279), and 0.0% (0/378), respectively. Bias evaluation revealed acceptable results for both Gram-negatives and Gram-positives (-12.4% and -6.5%, respectively). The LC yielded the detection of 14/18 carbapenemase producers by LFIA. In terms of turnaround time, the ID, AST, and carbapenemase detection results were generally obtained one day earlier with the FAST System compared with the SOC workflow.
The ID, AST, and carbapenemase detection results generated with the FAST System LC were highly concordant with the conventional workflow. The LC allowed species ID and carbapenemase detection within around 1 h after blood culture positivity and AST results within approximately 24 h, which is a significant reduction in the turnaround time of the PBC workflow.
本研究的目的是评估通过FAST系统（Qvella，加拿大安大略省里士满山）直接从阳性血培养物（PBC）中生成的Liquid Colony™（LC）在快速鉴定（ID）和抗菌药物敏感性测试（AST）方面的性能，并与标准护理（SOC）工作流程进行比较。
对匿名的PBC进行平行处理，分别采用FAST系统和FAST PBC Prep试剂盒（运行时间35分钟）以及SOC。通过基质辅助激光解吸电离飞行时间质谱（MALDI-ToF MS，美国马萨诸塞州比勒里卡的布鲁克公司）进行鉴定。通过参考肉汤微量稀释法（德国伯恩海姆的Merlin Diagnostika公司）进行AST。采用侧向流免疫色谱分析（LFIA）RESIST-5 O.O.K.N.V.（比利时根特的Coris公司）进行碳青霉烯酶检测。排除了多微生物PBC和含有酵母的样本。
共评估了241份PBC。鉴定结果显示，LC与SOC之间的属水平一致性为100%，种水平一致性为97.8%。革兰氏阴性菌的AST结果显示，分类一致性（CA）为99.1%（1578/1593），轻微误差（mE）、主要误差（ME）和非常主要误差（VME）率分别为0.6%（10/1593）、0.3%（3/1122）和0.4%（2/471）。革兰氏阳性菌的结果显示，CA为99.6%（1655/1662），mE、ME和VME率分别为0.3%（5/1662）、0.2%（2/1279）和0.0%（0/378）。偏差评估显示，革兰氏阴性菌和革兰氏阳性菌的结果均可接受（分别为-12.4%和-6.5%）。LC通过LFIA检测出18份碳青霉烯酶产生菌中的14份。在周转时间方面，与SOC工作流程相比，使用FAST系统通常可提前一天获得ID、AST和碳青霉烯酶检测结果。
FAST系统LC产生的ID、AST和碳青霉烯酶检测结果与传统工作流程高度一致。LC能够在血培养阳性后约1小时内进行菌种鉴定和碳青霉烯酶检测，约24小时内获得AST结果，这显著缩短了PBC工作流程的周转时间。
