Abstract

The ability of nosocomial opportunistic microorganism, K. pneumoniae, to produce biofilms on food and hospital surfaces is crucial to the development of infection which has adverse effects on patient outcome and survival. The present study aimed to evaluate the impact of probiotic Nisin producing L. lactis and TiO₂ NPs on the biofilm formation of K. pneumoniae. L. lactis isolates were commercially obtained and TiO₂ NPs were produced using a sol–gel method. 62 K. pneumoniae strains were isolated in three hospitals in Tehran, and food samples. The antimicrobial activity of L. lactis and TiO₂ NPs against antibiotic-resistant biofilm producing strains was determined via well-diffusion method. Definitive identification of isolates was performed through conventional biochemical tests and 16SrRNA PCR. The biofilm formation ability among the isolates obtained from sputum was higher than other isolates (p < 0.001). The L. lactis inhibited biofilm production in 4 isolates, but failed to prevent the growth of the 13 isolates. Additionally, TiO₂ NPs inhibited 14 isolates to form a biofilm at 256 μg/mL. Comparison of LuxS gene expression in K. pneumoniae untreated and treated with TiO₂ NPs alone and TiO₂ + L. lactis showed –2.04 and –3.85 fold changes (CI = 95%, p = 0.006 and p = 0.002, respectively). The synthesized TiO₂ nanoparticles are effective against these biofilms forming multidrug resistant K. pneumoniae strains and can be considered as reliable and operative inorganic antimicrobial agents. Antimicrobial and antibiofilm effects of TiO₂ nanoparticles can be synergically elevated in combination with probiotic Nisin producing L. lactis.

中文翻译：

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益生菌乳酸乳球菌和二氧化钛纳米颗粒对肺炎克雷伯菌生物膜基因表达的影响；比较研究

摘要

院内机会性微生物肺炎克雷伯菌在食物和医院表面产生生物膜的能力对于感染的发展至关重要，感染对患者的预后和生存有不利影响。本研究旨在评估益生菌乳酸链球菌肽和 TiO ₂ NPs 对肺炎克雷伯菌生物膜形成的影响。L.lactis分离株是商业获得的，TiO ₂ NPs 是使用溶胶-凝胶方法生产的。在德黑兰的 3 家医院和食品样本中分离出了62株肺炎克雷伯菌。L.lactis和 TiO ₂的抗菌活性通过良好扩散法测定抗抗生素抗性生物膜产生菌株的纳米颗粒。通过常规生化测试和 16SrRNA PCR 对分离株进行最终鉴定。从痰中获得的分离物的生物膜形成能力高于其他分离物（p < 0.001）。在乳酸乳球菌中分离4抑制生物膜生产，但未能阻止13株的生长。此外，TiO ₂ NPs 在 256 μg/mL 时抑制了 14 个分离物形成生物膜。比较LuxS基因表达肺炎克雷伯未处理的和有TiO处理_2周单独的NP和TiO ₂ +乳酸乳球菌显示 –2.04 和 –3.85 倍的变化（CI = 95%，分别为p = 0.006 和p = 0.002）。合成的 TiO ₂纳米颗粒对形成多重耐药肺炎克雷伯菌菌株的这些生物膜有效，可被视为可靠且有效的无机抗菌剂。TiO ₂纳米颗粒的抗微生物和抗生物膜作用可以与产生乳酸乳球菌的益生菌乳链菌肽相结合而协同提高。