Mahfouz Amira M, Eraqi Walaa A, El Hifnawi Hala Nour El Din, Shawky Alaa El Din, Samir Reham, Ramadan Mohamed A
Department of Drug Radiation Research, Division of Biotechnology, Laboratory of Drug Microbiology, National Center for Radiation Research and Technology (NCRRT), Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt.
Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Kasr El-Aini Street, Cairo, 11562, Egypt.
BMC Microbiol. 2025 Jan 13;25(1):18. doi: 10.1186/s12866-024-03682-x.
One of the main issues facing public health with microbial infections is antibiotic resistance. Nanoparticles (NPs) are among the best alternatives to overcome this issue. Silver nanoparticle (AgNPs) preparations are widely applied to treat multidrug-resistant pathogens. Therefore, there is an urgent need for greater knowledge regarding the effects of improper and excessive use of these medications. The current study describes the consequences of long-term exposure to sub-lethal concentrations of AgNPs on the bacterial sensitivity to NPs and the reflection of this change on the bacterial genome.
Chemical methods have been used to prepare AgNPs and gamma irradiation has been utilized to produce more stable AgNPs. Different techniques were used to characterize and identify the prepared AgNPs including UV-visible spectrophotometer, Fourier Transform Infrared (FT-IR), Dynamic light scattering (DLS), and zeta potential. Transmission electron microscope (TEM) and Scanning electron microscope (SEM) showed 50-100 nm spherical-shaped AgNPs. Eleven gram-negative and gram-positive bacterial isolates were collected from different wound infections. The minimum inhibitory concentrations (MICs) of AgNPs against the tested isolates were evaluated using the agar dilution method. This was followed by the induction of bacterial resistance to AgNPs using increasing concentrations of AgNPs. All isolates changed their susceptibility level to become resistant to high concentrations of AgNPs upon recultivation at increasing concentrations of AgNPs. Whole genome sequencing (WGS) was performed on selected susceptible isolates of gram-positive Staphylococcus lentus (St.L.1), gram-negative Klebsiella pneumonia (KP.1), and their resistant isolates St.L_R.Ag and KP_R.Ag to detect the genomic changes and mutations.
For the detection of single-nucleotide polymorphisms (SNPs) and the identification of all variants (SNPs, insertions, and deletions) in our isolates, the Variation Analysis Service tool available in the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) was used. Compared to the susceptible isolates, the AgNPs-resistant isolates St.L_R.Ag and KP_R.Ag had unique mutations in specific efflux pump systems, stress response, outer membrane proteins, and permeases. These findings might help to explain how single-nucleotide variants contribute to AgNPs resistance. Consequently, strict regulations and rules regarding the use and disposal of nano waste worldwide, strict knowledge of microbe-nanoparticle interaction, and the regulated disposal of NPs are required to prevent pathogens from developing nanoparticle resistance.
微生物感染给公共卫生带来的主要问题之一是抗生素耐药性。纳米颗粒（NPs）是克服这一问题的最佳替代方案之一。银纳米颗粒（AgNPs）制剂被广泛应用于治疗多重耐药病原体。因此，迫切需要更多关于这些药物不当和过度使用影响的知识。本研究描述了长期暴露于亚致死浓度的AgNPs对细菌对NPs敏感性的影响以及这种变化在细菌基因组上的反映。
已使用化学方法制备AgNPs，并利用伽马射线辐照来生产更稳定的AgNPs。使用了不同技术来表征和鉴定所制备的AgNPs，包括紫外可见分光光度计、傅里叶变换红外光谱（FT-IR）、动态光散射（DLS）和zeta电位。透射电子显微镜（TEM）和扫描电子显微镜（SEM）显示为50-100纳米的球形AgNPs。从不同伤口感染中收集了11株革兰氏阴性和革兰氏阳性细菌分离株。使用琼脂稀释法评估AgNPs对受试分离株的最低抑菌浓度（MICs）。随后使用浓度递增的AgNPs诱导细菌对AgNPs产生耐药性。在浓度递增的AgNPs中再次培养后，所有分离株的敏感性水平均发生变化，对高浓度的AgNPs产生耐药性。对革兰氏阳性缓症葡萄球菌（St.L.1）、革兰氏阴性肺炎克雷伯菌（KP.1）及其耐药分离株St.L_R.Ag和KP_R.Ag的选定敏感分离株进行了全基因组测序（WGS），以检测基因组变化和突变。
为了检测我们分离株中的单核苷酸多态性（SNP）并鉴定所有变异（SNP、插入和缺失），使用了细菌和病毒生物信息学资源中心（BV-BRC）提供的变异分析服务工具。与敏感分离株相比，耐AgNPs分离株St.L_R.Ag和KP_R.Ag在特定的外排泵系统、应激反应、外膜蛋白和通透酶中具有独特的突变。这些发现可能有助于解释单核苷酸变异如何导致对AgNPs的耐药性。因此，需要在全球范围内制定关于纳米废物使用和处置的严格法规和规则，深入了解微生物与纳米颗粒的相互作用，并对NPs进行规范处置，以防止病原体产生纳米颗粒耐药性。
