Uzoechi Samuel C, Abu-Lail Nehal I
Department of Biomedical Technology, Federal University of Technology, Owerri PMB 1526, Nigeria.
Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, USA.
Antibiotics (Basel). 2020 May 7;9(5):235. doi: 10.3390/antibiotics9050235.
Persister bacterial cells are great at surviving antibiotics. The phenotypic means by which they do that are underexplored. As such, atomic force microscope (AFM) was used to quantify the contributions of the surface properties of the outer membrane of multidrug resistance (MDR)- Strains (A5 and A9) in the presence of ampicillin at minimum inhibitory concentration (MIC) (resistant cells) and at 20× MIC (persistent cells). The properties quantified were morphology, root mean square (RMS) roughness, adhesion, elasticity, and bacterial surface biopolymers' thickness and grafting density. Compared to untreated cells, persister cells of A5 increased their RMS, adhesion, apparent grafting density, and elasticity by 1.2, 3.4, 2.0, and 3.3 folds, respectively, and decreased their surface area and brush thickness by 1.3 and 1.2 folds, respectively. Similarly, compared to untreated cells, persister cells of A9 increased their RMS, adhesion and elasticity by 1.6, 4.4, and 4.5 folds, respectively; decreased their surface area and brush thickness by 1.4 and 1.6 folds, respectively; and did not change their grafting densities. Our results indicate that resistant and persistent A5 cells battled ampicillin by decreasing their size and going through dormancy. The resistant A9 cells resisted ampicillin through elongation, increased surface area, and adhesion. In contrast, the persistent E. A9 cells resisted ampicillin through increased roughness, increased surface biopolymers' grafting densities, increased cellular elasticities, and decreased surface areas. Mechanistic insights into how the resistant and persistent cells respond to ampicillin's treatment are instrumental to guide design efforts exploring the development of new antibiotics or renovating the existing antibiotics that may kill persistent bacteria by combining more than one mechanism of action.
持留菌细胞在抗生素环境中具有很强的存活能力。然而，它们实现这一特性的表型机制尚未得到充分研究。因此，本研究使用原子力显微镜（AFM）来量化多药耐药（MDR）菌株（A5和A9）外膜表面特性在氨苄西林最低抑菌浓度（MIC）（耐药细胞）和20倍MIC（持留菌细胞）条件下的作用。所量化的特性包括形态、均方根（RMS）粗糙度、粘附力、弹性以及细菌表面生物聚合物的厚度和接枝密度。与未处理的细胞相比，A5菌株的持留菌细胞的RMS、粘附力、表观接枝密度和弹性分别增加了1.2倍、3.4倍、2.0倍和3.3倍，而表面积和刷状厚度分别减少了1.3倍和1.2倍。同样，与未处理的细胞相比，A9菌株的持留菌细胞的RMS、粘附力和弹性分别增加了1.6倍、4.4倍和4.5倍；表面积和刷状厚度分别减少了1.4倍和1.6倍；接枝密度没有变化。我们的结果表明，耐药和持留的A5细胞通过减小尺寸和进入休眠状态来对抗氨苄西林。耐药的A9细胞通过伸长、增加表面积和粘附力来抵抗氨苄西林。相比之下，持留的A9细胞通过增加粗糙度、增加表面生物聚合物的接枝密度、增加细胞弹性和减小表面积来抵抗氨苄西林。深入了解耐药和持留细胞对氨苄西林治疗的反应机制，有助于指导新型抗生素的研发或对现有抗生素进行改造，通过多种作用机制联合使用来杀死持留菌。
