Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Carretera Colmenar Viejo Km 9, 1, 28034, Madrid, Spain.
Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
Eur J Clin Microbiol Infect Dis. 2019 Jun;38(6):1095-1104. doi: 10.1007/s10096-019-03498-y. Epub 2019 Feb 2.
To standardize the methodology for conducting direct antimicrobial susceptibility testing (AST) of Enterobacterales and Pseudomonas aeruginosa causing bacteremia from positive blood culture pellets. Two methods for processing positive blood cultures with Enterobacterales and P. aeruginosa were compared: a conventional method for identification and AST versus a direct method obtaining a pellet for both matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) identification and direct AST. A total of 157 (145 Enterobacterales, 12 P. aeruginosa) positive blood cultures were included. Microorganism identification showed 100% concordance between both methods at species and genus level. Definitive AST results were obtained 24 h earlier with the rapid method than the conventional one (p < 0.001). Of the 2814 MICs generated, there were discrepancies with respect to the conventional method in 47 (1.7%), 0.3% being very major (VME) and 1.3% major (ME) errors. Better results for AST were obtained when colony counts with the pellet were ≥ 10 cfu/ml. The essential agreement (EA) for antibiotics tested in Enterobacterales was at least 97%, except for ampicillin (95%). Regardless of colony count, the greatest discrepancies were observed for first/s-generation cephalosporins and aminoglycosides. In P. aeruginosa, EA was at least 92%, except for piperacillin-tazobactam (84%) and cefepime (76%). No VME occurred except for ceftazidime (8%). ME occurred in piperacillin/tazobactam (16%), ticarcillin, ceftazidime, tobramycin, amikacin, and colistin (8% each). Direct use of the blood culture pellet permits fast AST in bacteremia of Enterobacterales, enabling the clinicians to perform an early treatment adjustment. However, for Pseudomonas aeruginosa, the data needs expanding to improve the reliability of this technique.
为了规范从阳性血培养颗粒中分离出的肠杆菌科和铜绿假单胞菌引起菌血症的直接抗菌药敏试验（AST）方法。比较了两种处理肠杆菌科和铜绿假单胞菌阳性血培养的方法：一种是传统的鉴定和 AST 方法，另一种是直接方法，从基质辅助激光解吸/电离时间飞行（MALDI-TOF）鉴定和直接 AST 中获得一个颗粒。共纳入 157 株（145 株肠杆菌科，12 株铜绿假单胞菌）阳性血培养物。两种方法在种和属水平上的微生物鉴定结果完全一致。快速方法比传统方法获得明确的 AST 结果早 24 小时（p < 0.001）。在生成的 2814 个 MIC 中，与传统方法相比，有 47 个（1.7%）存在差异，0.3%为非常大（VME）错误，1.3%为主要（ME）错误。当颗粒的菌落计数≥10cfu/ml 时，AST 结果更好。在肠杆菌科测试的抗生素的基本一致（EA）率至少为 97%，除了氨苄西林（95%）。无论菌落计数如何，第一代/第二代头孢菌素和氨基糖苷类药物的差异最大。在铜绿假单胞菌中，EA 至少为 92%，除了哌拉西林-他唑巴坦（84%）和头孢吡肟（76%）。除头孢他啶（8%）外，无 VME。ME 发生在哌拉西林/他唑巴坦（16%）、替卡西林、头孢他啶、妥布霉素、阿米卡星和粘菌素（8%）中。直接使用血培养颗粒可快速进行肠杆菌科菌血症的 AST，使临床医生能够进行早期治疗调整。然而，对于铜绿假单胞菌，需要扩大数据以提高该技术的可靠性。
