Eskisehir Osmangazi University, Department of Microbiology, Faculty of Medicine, Eskisehir, Turkey.
Suleyman Demirel University, Faculty of Pharmacy, Pharmaceutical Microbiology, Isparta, Turkey.
Indian J Med Microbiol. 2022 Oct-Dec;40(4):567-571. doi: 10.1016/j.ijmmb.2022.06.009. Epub 2022 Jul 8.
We aimed to compare the results of the BD Phoenix (TM) M50 ID/AST system and the gold standard broth microdilution method. We also evaluated the potential of a new therapeutic combination (colistin/sulbactam) for colistin resistance among Acinetobacter baumanni strains.
Growth in blood samples was detected with the BACTEC (BD Becton Dickinson, ABD) continuous monitoring blood culture system. Strains were identified by Phoenix (BD Phoenix™ M50, ABD) automated bacterial identification system and antimicrobial susceptibility results were obtained. A total of 92 A. baumannii complex isolates showing resistance to at least three antibiotic classes were included in the study. Colistin susceptibility results (both susceptible and resistant strains) detected by the Phoenix device were confirmed by the reference method, the liquid microdilution method. The concentration index (FIC) was used to determine the efficacy of fractional inhibitor drug combinations, the efficacy of colistin/sulbactam combination against 50 multiresistant A. baumannii complex strains was investigated using the checkerboard method.
10 (10.9%) of 92 isolates were resistant to colistin and 80 (86.9%) to sulbactam. With the automation system, only 2 of 10 isolates were found resistant to colistin, while 8 isolates were susceptible. For this reason, the very major error rate of the Phoenix M50 automatic system among resistant isolates was determined as 8/10. It was determined that 6 (12%) of the colistin/sulbactam combination had a synergistic effect and 44 (88%) had an additive interaction. No antagonistic interaction was detected with the colistin-sulbactam combination in this study.
A. baumannii strains should be confirmed by the broth microdilution method, which is the reference method, against the MIC results detected by automated systems. It was concluded that the use of colistin alone should be avoided in the treatment of A. baumannii infections.
我们旨在比较 BD Phoenix（TM）M50 ID/AST 系统和金标准肉汤微量稀释法的结果。我们还评估了新的治疗组合（多粘菌素/舒巴坦）对鲍曼不动杆菌菌株中多粘菌素耐药性的潜力。
使用 BACTEC（BD Becton Dickinson，ABD）连续监测血液培养系统检测血液样本中的生长情况。通过 Phoenix（BD PhoenixTM M50，ABD）自动化细菌鉴定系统鉴定菌株，并获得抗菌药物敏感性结果。共有 92 株对至少三种抗生素类别表现出耐药性的鲍曼不动杆菌复合体分离株纳入研究。通过 Phoenix 仪器检测到的多粘菌素敏感性结果（敏感和耐药菌株）通过参考方法，即液体微量稀释法进行确认。使用浓度指数（FIC）来确定部分抑制剂药物组合的疗效，使用棋盘法研究了多粘菌素/舒巴坦组合对 50 株多耐药鲍曼不动杆菌复合体菌株的疗效。
92 株分离株中，10 株（10.9%）对多粘菌素耐药，80 株（86.9%）对舒巴坦耐药。使用自动化系统，仅在 10 株分离株中发现 2 株对多粘菌素耐药，而 8 株分离株敏感。因此，Phoenix M50 自动系统在耐药分离株中的非常大错误率确定为 8/10。确定该组合中有 6 株（12%）具有协同作用，44 株（88%）具有相加作用。在本研究中，未检测到多粘菌素-舒巴坦组合的拮抗作用。
应使用肉汤微量稀释法（参考方法）确认对自动化系统检测到的 MIC 结果为鲍曼不动杆菌菌株。结论是在治疗鲍曼不动杆菌感染时应避免单独使用多粘菌素。
