Department of Biomolecular Sciences, University of Urbino, 61029 Urbino, PU, Italy.
Department of Biomolecular Sciences, University of Urbino, 61029 Urbino, PU, Italy.
Int J Biol Macromol. 2018 Oct 15;118(Pt B):2193-2200. doi: 10.1016/j.ijbiomac.2018.07.088. Epub 2018 Jul 19.
Urinary catheters contamination by microorganisms is a major cause of hospital acquired infections and represents a limitation for long-term use. In this work, biofilms of Klebsiella pneumoniae and Escherichia coli clinical isolates were developed on urinary catheters for 48 and 72 h in artificial urine medium (AUM) with different molecular weight chitosans (AUM-CS solutions) at pH 5.0. The number of viable bacteria was determined by standard plate count agar while crystal violet (CV) staining was carried out to assess biomass production (optical density at 570 nm) in the mentioned conditions. Re-growth of each strain was also evaluated after 24 h re-incubation of the treated catheters. Significant decreases of log CFU/catheter and biomass production were observed for all the biofilms developed in AUM-CS compared with the controls in AUM. The percentages of biofilm removal were slightly higher for E. coli biofilms (up to 90.4%) than those of K. pneumoniae (89.7%); in most cases, the complete inhibition of bacterial re-growth on treated catheter pieces was observed. Contact time influenced chitosan efficacy rather than its molecular weight or the biofilms age. The results confirmed the potentiality of chitosans as a biomacromolecule tool to contrast biofilm formation and reduce bacterial re-growth on urinary catheters.
微生物污染导尿管是医院获得性感染的主要原因，也是长期使用的限制因素。在这项工作中，在 pH 值为 5.0 的人工尿液培养基（AUM）中，将临床分离的肺炎克雷伯菌和大肠杆菌生物膜在导尿管上分别培养 48 和 72 小时，同时使用不同分子量的壳聚糖（AUM-CS 溶液）。通过标准平板计数琼脂测定活菌数量，并用结晶紫（CV）染色法评估在上述条件下生物量的产生（570nm 处的光密度）。在处理后的导尿管再孵育 24 小时后，还评估了每种菌株的再生长情况。与 AUM 中的对照相比，所有在 AUM-CS 中形成的生物膜的 CFU/导管对数和生物量均显著降低。与肺炎克雷伯菌生物膜（高达 90.4%）相比，大肠杆菌生物膜的生物膜去除率略高（89.7%）；在大多数情况下，观察到处理后的导管上细菌再生长完全受到抑制。接触时间影响壳聚糖的功效，而不是其分子量或生物膜的老化。研究结果证实了壳聚糖作为一种生物大分子工具的潜力，可用于抑制生物膜的形成，并减少导尿管上细菌的再生长。
