不同表面电荷的多黏菌素敏感和耐药鲍曼不动杆菌细胞用 ζ 电位测量作为生长阶段和多黏菌素处理的函数。
Different surface charge of colistin-susceptible and -resistant Acinetobacter baumannii cells measured with zeta potential as a function of growth phase and colistin treatment.
机构信息
Facility for Anti-infective Drug Development and Innovation, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia.
出版信息
J Antimicrob Chemother. 2011 Jan;66(1):126-33. doi: 10.1093/jac/dkq422. Epub 2010 Nov 16.
OBJECTIVES
electrostatic forces mediate the initial interaction between cationic colistin and Gram-negative bacterial cells. Lipopolysaccharide (LPS) loss mediates colistin resistance in some A. baumannii strains. Our aim was to determine the surface charge of colistin-susceptible and -resistant A. baumannii as a function of growth phase and in response to polymyxin treatment.
METHODS
the zeta potential of A. baumannii ATCC 19606 and 10 clinical multidrug-resistant strains (MICs 0.5-2 mg/L) was assessed. Colistin-resistant derivatives (MIC >128 mg/L) of wild-type strains were selected in the presence of 10 mg/L colistin, including the LPS-deficient lpxA mutant, ATCC 19606R. To determine the contribution of LPS to surface charge, two complemented ATCC 19606R derivatives were examined, namely ATCC 19606R + lpxA (containing an intact lpxA gene) and ATCC 19606R + V (containing empty vector). Investigations were conducted as a function of growth phase and polymyxin treatment (1, 4 and 8 mg/L).
RESULTS
wild-type cells exhibited a greater negative charge (-60.5 ± 2.36 to -26.2 ± 2.56 mV) thancolistin-resistant cells (-49.2 ± 3.09 to -19.1 ± 2.80 mV) at mid-log phase (ANOVA, P < 0.05). Opposing growth-phase trends were observed for both phenotypes: wild-type cells displayed reduced negative charge and colistin-resistant cells displayed increased negative charge at stationary compared with mid-logarithmic phase. Polymyxin exposure resulted in a concentration-dependent increase in zeta potential. Examination of ATCC 19606R and complemented strains supported the importance of LPS in determining surface charge, suggesting a potential mechanism of colistin resistance.
CONCLUSIONS
zeta potential differences between A. baumannii phenotypes probably reflect compositional outer-membrane variations that impact the electrostatic component of colistin activity.
目的
静电作用力介导阳离子多粘菌素与革兰氏阴性细菌细胞的初始相互作用。脂多糖（LPS）的丢失介导某些鲍曼不动杆菌菌株对多粘菌素的耐药性。我们的目的是确定多粘菌素敏感和耐药的鲍曼不动杆菌的表面电荷作为生长阶段的函数，并响应多粘菌素处理。
方法
评估了鲍曼不动杆菌 ATCC 19606 和 10 株临床多药耐药株（MIC 0.5-2mg/L）的 ζ 电位。在 10mg/L 多粘菌素存在的情况下，选择野生型菌株的多粘菌素耐药衍生物（MIC>128mg/L），包括 LPS 缺陷型 lpxA 突变体 ATCC 19606R。为了确定 LPS 对表面电荷的贡献，研究了两个互补的 ATCC 19606R 衍生物，即 ATCC 19606R+lpxA（含有完整的 lpxA 基因）和 ATCC 19606R+V（含有空载体）。研究了生长阶段和多粘菌素处理（1、4 和 8mg/L）的功能。
结果
在对数中期，野生型细胞表现出比多粘菌素耐药细胞更大的负电荷（-60.5 ± 2.36 至-26.2 ± 2.56mV）（方差分析，P <0.05）。两种表型都观察到了相反的生长阶段趋势：与对数中期相比，野生型细胞的负电荷减少，多粘菌素耐药细胞的负电荷增加。多粘菌素暴露导致 ζ 电位呈浓度依赖性增加。对 ATCC 19606R 和互补菌株的研究支持 LPS 在确定表面电荷中的重要性，这表明了多粘菌素耐药的潜在机制。
结论
鲍曼不动杆菌表型之间的 ζ 电位差异可能反映了影响多粘菌素活性静电成分的外膜组成变化。
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