Department of Microbial Infection and Immunity, Microbiology, The Ohio State University, Columbus, OH, 43210, USA.
Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902, USA.
Sci Rep. 2018 Jun 26;8(1):9691. doi: 10.1038/s41598-018-28009-5.
Pseudomonas aeruginosa evolves during chronic pulmonary infections of cystic fibrosis (CF) patients, forming pathoadapted variants that are persistent. Mucoid and rugose small-colony variants (RSCVs) are typically isolated from sputum of CF patients. These variants overproduce exopolysaccharides in the biofilm extracellular polymeric substance (EPS). Currently, changes to the biophysical properties of RSCV and mucoid biofilms due to variations in EPS are not well understood. This knowledge may reveal how lung infections resist host clearance mechanisms. Here, we used mechanical indentation and shear rheometry to analyse the viscoelasticity of RSCV and mucoid colony-biofilms compared to their isogenic parent at 2-, 4-, and 6-d. While the viscoelasticity of parental colony-biofilms underwent fluctuating temporal changes, in contrast, RSCV and mucoid colony-biofilms showed a gradual progression to more elastic-solid behaviour. Theoretical indices of mucociliary and cough clearance predict that mature 6-d parental and RSCV biofilms may show reduced cough clearance from the lung, while early mucoid biofilms may show reduced clearance by both mechanisms. We propose that viscoelasticity be considered a virulence property of biofilms.
铜绿假单胞菌在囊性纤维化 (CF) 患者的慢性肺部感染中进化，形成持久的病理适应变体。粘液化和粗糙小菌落变体 (RSCV) 通常从 CF 患者的痰液中分离出来。这些变体在生物膜细胞外聚合物物质 (EPS) 中过度产生胞外多糖。目前，由于 EPS 的变化，RSCV 和粘液化生物膜的生物物理性质的变化还没有得到很好的理解。这方面的知识可能揭示肺部感染如何抵抗宿主清除机制。在这里，我们使用机械压痕和剪切流变学分析了 RSCV 和粘液化菌落生物膜与它们的同基因亲本在 2、4 和 6 天的黏弹性。虽然亲本菌落生物膜的黏弹性经历了波动的时间变化，但相比之下，RSCV 和粘液化菌落生物膜表现出逐渐向更有弹性的固体行为转变。黏液纤毛清除和咳嗽清除的理论指数预测，成熟的 6 天亲本和 RSCV 生物膜可能会减少肺部的咳嗽清除，而早期的粘液化生物膜可能会通过两种机制减少清除。我们提出将黏弹性视为生物膜的毒力特性。
