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首页> 外文期刊>Antimicrobial agents and chemotherapy. >Atomic force microscopy investigation of the morphology and topography of colistin-heteroresistant Acinetobacter baumannii strains as a function of growth phase and in response to colistin treatment.
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Atomic force microscopy investigation of the morphology and topography of colistin-heteroresistant Acinetobacter baumannii strains as a function of growth phase and in response to colistin treatment.

机译：大肠埃希氏菌-异抗鲍曼不动杆菌菌株的形态和形貌的原子力显微镜研究，作为生长期和对大肠菌素处理的响应。

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The prevalence of infections caused by multidrug-resistant gram-negative Acinetobacter baumannii strains and the lack of novel antibiotics under development are posing a global dilemma, forcing a resurgence of the last-line antibiotic colistin. Our aim was to use atomic force microscopy (AFM) to investigate the morphology and topography of paired colistin-susceptible and -resistant cells from colistin-heteroresistant A. baumannii strains as a function of bacterial growth phase and colistin exposure. An optimal AFM bacterial sample preparation protocol was established and applied to examine three paired strains. Images revealed rod-shaped colistin-susceptible cells (1.65 +/- 0.27 microm by 0.98 +/- 0.07 microm) at mid-logarithmic phase, in contrast to spherical colistin-resistant cells (1.03 +/- 0.09 microm); the latter were also more diverse in appearance and exhibited a rougher surface topography (7.05 +/- 1.3 nm versus 11.4 +/- 2.5 nm for susceptible versus resistant, respectively). Cellular elongation up to approximately 18 microm at stationary phase was more commonly observed in susceptible strains, although these "worm-like" cells were also observed occasionally in the resistant population. The effects of colistin exposure on the cell surface of colistin-susceptible and -resistant cells were found to be similar; topographical changes were minor in response to 0.5 microg/ml colistin; however, at 4 microg/ml colistin, a significant degree of surface disruption was detected. At 32 microg/ml colistin, cellular clumping and surface smoothening were evident. Our study has demonstrated for the first time substantial morphological and topographical differences between colistin-susceptible and -resistant cells from heteroresistant A. baumannii strains. These results contribute to an understanding of colistin action and resistance in regard to this problematic pathogen.
机译：由多重耐药的革兰氏阴性不动杆菌鲍曼不动杆菌菌株引起的感染流行和正在开发的新型抗生素的缺乏构成了全球难题，迫使最后一线抗生素大肠菌素重新流行。我们的目的是使用原子力显微镜（AFM）来研究成对的细菌对大肠杆菌异种耐药的鲍曼不动杆菌的成对大肠杆菌敏感和耐药细胞的形态和形貌与细菌生长阶段和大肠杆菌粘菌暴露的关系。建立了最佳的AFM细菌样品制备方案，并将其应用于检查三对菌株。图像显示在对数中期，杆状粘菌素敏感细胞（1.65 +/- 0.27微米乘0.98 +/- 0.07微米），与球形粘菌素耐药细胞（1.03 +/- 0.09微米）相反;后者的外观也更加多样化，并且显示出较粗糙的表面形貌（感性与抗性分别为7.05 +/- 1.3 nm和11.4 +/- 2.5 nm）。在易感菌株中更常观察到在固定相时细胞伸长高达约18微米，尽管有时在抗性种群中也观察到这些“蠕虫状”细胞。发现粘菌素暴露对粘菌素敏感和耐药细胞表面的影响是相似的。响应0.5 microg / ml大肠菌素，地形变化很小。但是，在4 microg / ml colistin下，检测到了很大程度的表面破坏。在大肠菌素为32微克/毫升时，细胞团块和表面平滑度很明显。我们的研究首次证明了来自异抗性鲍曼不动杆菌菌株的大肠菌素敏感和抗性细胞之间的形态学和地形学差异。这些结果有助于人们了解大肠粘菌素对这种有问题的病原菌的作用和抵抗力。

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