1Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade, Belgrade, 11000, Serbia.
2Department of Microbiology and Immunology, Faculty of Medicine, University of Banja Luka, Banja Luka, Republic of Srpska, 78000, Bosnia and Herzegovina.
Acta Microbiol Immunol Hung. 2020 Mar 9;67(3):176-181. doi: 10.1556/030.2020.01079.
Tigecycline can be effective to treat infections of carbapenem-resistant Acinetobacter baumannii (CRAB) however, no interpretive criteria have been approved so far. The objectives of this study were to evaluate the proportion of CRAB isolates and to compare gradient test with a broth microdilution (BMD) method for tigecycline susceptibility testing of A. baumannii.This study included 349 multidrug-resistant (MDR) Acinetobacter spp. collected from Serbia, Montenegro, Bosnia and Herzegovina in 2016 and 2017. Antibiotic susceptibility testing was performed by disk diffusion, VITEK2, gradient, ComASP Colistin. Tigecycline susceptibilities were interpreted according to breakpoints of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Food and Drug Administration (FDA).Majority of the tested isolates were CRAB (92.8%). Tigecycline MIC50/MIC90 values were 4/8 μg/mL by BMD and 0.5/4 μg/mL by gradient test. Essential agreement for BMD and gradient test amounted to 65.1%. With EUCAST breakpoints, categorical agreement (CA) was achieved in 38% isolates. Major discordance (MD-false susceptibility/resistance) and minor discordance (mD-false categorization involving intermediate results) were observed in 10% and 57% A. baumannii, respectively. With FDA breakpoints, CA, MD and mD were observed in 44%, 16% and 47% isolates, respectively. Colistin resistance was 2.1%.The study highlights a high proportion of CRAB and several discordances between BMD and gradient test which may lead to inappropriate therapy.
替加环素可有效治疗碳青霉烯类耐药鲍曼不动杆菌（CRAB）感染，但迄今为止尚未批准任何解释标准。本研究的目的是评估 CRAB 分离株的比例，并比较梯度试验与肉汤微量稀释（BMD）法用于鲍曼不动杆菌替加环素药敏试验。本研究纳入了 2016 年至 2017 年期间从塞尔维亚、黑山和波斯尼亚和黑塞哥维那收集的 349 株多药耐药（MDR）不动杆菌属。药敏试验采用纸片扩散法、VITEK2、梯度法和 ComASP 黏菌素进行。替加环素药敏试验结果根据欧洲抗菌药物敏感性试验委员会（EUCAST）和美国食品药品监督管理局（FDA）的折点进行解释。大多数受试分离株为 CRAB（92.8%）。BMD 法和梯度法替加环素 MIC50/MIC90 值分别为 4/8μg/mL 和 0.5/4μg/mL。BMD 和梯度法的基本符合率为 65.1%。根据 EUCAST 折点，38%的分离株达到分类一致（CA）。在 10%的鲍曼不动杆菌中观察到主要不吻合（MD-假敏感/耐药）和次要不吻合（mD-涉及中介结果的假分类），而在 57%的鲍曼不动杆菌中观察到次要不吻合。根据 FDA 折点，44%、16%和 47%的分离株分别达到 CA、MD 和 mD。黏菌素耐药率为 2.1%。本研究突出了 CRAB 的高比例以及 BMD 和梯度试验之间的几种不吻合，这可能导致不适当的治疗。
