School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada.
Antimicrob Agents Chemother. 2017 Oct 24;61(11). doi: 10.1128/AAC.00415-17. Print 2017 Nov.
Increasing antibiotic resistance among pathogenic bacterial species is a serious public health problem and has prompted research examining the antibacterial effects of alternative compounds and novel treatment strategies. Compounding this problem is the ability of many pathogenic bacteria to form biofilms during chronic infections. Importantly, these communities are often recalcitrant to antibiotic treatments that show effectiveness against acute infection. The antimicrobial properties of silver have been known for decades, but recently silver and silver-containing compounds have seen renewed interest as antimicrobial agents for treating bacterial infections. The goal of this study was to assess the ability of citrate-capped silver nanoparticles (AgNPs) of various sizes, alone and in combination with the aminoglycoside antibiotic tobramycin, to inhibit established biofilms. Our results demonstrate that smaller 10-nm and 20-nm AgNPs were more effective at synergistically potentiating the activity of tobramycin. Visualization of biofilms treated with combinations of 10-nm AgNPs and tobramycin reveals that the synergistic bactericidal effect may be caused by disrupting cellular membranes. Minimum biofilm eradication concentration (MBEC) assays using clinical isolates shows that small AgNPs are more effective than larger AgNPs at inhibiting biofilms, but that the synergy effect is likely a strain-dependent phenomenon. These data suggest that small AgNPs synergistically potentiate the activity of tobramycin against and may reveal a potential role for AgNP/antibiotic combinations in treating patients with chronic infections in a strain-specific manner.
在致病细菌物种中，抗生素耐药性的增加是一个严重的公共卫生问题，促使人们研究检查替代化合物和新的治疗策略的抗菌作用。使这个问题更加复杂的是，许多致病菌在慢性感染期间形成生物膜的能力。重要的是，这些群落通常对抗生素治疗具有抗性，而抗生素治疗对急性感染有效。银的抗菌特性已经存在了几十年，但最近银和含银化合物作为治疗细菌感染的抗菌剂重新引起了人们的兴趣。本研究的目的是评估不同大小的柠檬酸银纳米颗粒（AgNPs）单独使用以及与氨基糖苷类抗生素妥布霉素联合使用抑制已建立的生物膜的能力。我们的结果表明，较小的 10nm 和 20nm AgNPs 更有效地协同增强妥布霉素的活性。用 10nm AgNPs 和妥布霉素处理的生物膜的可视化显示，协同杀菌作用可能是由于破坏了细胞膜。使用临床分离株进行最低生物膜根除浓度（MBEC）测定表明，小的 AgNPs 比大的 AgNPs 更有效地抑制生物膜，但协同效应可能是一种菌株依赖性现象。这些数据表明，小的 AgNPs 协同增强了妥布霉素对生物膜的活性，并且可能揭示了 AgNP/抗生素联合治疗以菌株特异性方式治疗慢性感染患者的潜在作用。
