Mechanisms of antibiotic resistance in bacteria mediated by silver nanoparticles

作者：Chitrada Kaweeteerawat, Preeyawis Na Ubol, Sanirat Sangmuang, Sasitorn Aueviriyavit, Rawiwan Maniratanachote · 发表于：Journal of Toxicology and Environmental Health · 年份：2017 · DOI：10.1080/15287394.2017.1376727 · 被引用次数：166 · 研究领域：Nanoparticles: synthesis and applications

Silver nanoparticles (AgNPs) are widely used in industry, consumer products, and medical appliances due to their efficient antimicrobial properties. However, information on environmental toxicity and bacterial impact of these particles is not completely elucidated. Results showed that AgNPs produced growth inhibition and oxidative stress in bacteria Escherichia coli (gram negative) and Staphylococcus aureus (gram positive), with half-maximal inhibitory concentrations (IC50) of 12 and 7 mg/L, respectively. Surprisingly, bacteria pre-exposed to sublethal dose of AgNPs exhibited increased resistance toward antibiotics (ampicillin and Pen-Strep) with IC50 elevated by 3–13-fold. Further, AgNP pre-exposure raised the minimal inhibitory concentration and minimal biocidal concentration by two- to eightfold when cells were challenged with antibiotics with diverse mechanisms of action (penicillin, chloramphenicol, and kanamycin). Interestingly, we found that upon exposure to ampicillin, strains pretreated with AgNPs exhibited lower levels of membrane damage and oxidative stress, together with elevated levels of intracellular ATP relative to untreated cells. Bacterial reverse mutation assay (Ames test) showed that AgNPs are highly mutagenic, consistent with further assays demonstrating abiotic reactive oxygen species (ROS) generation and intrinsic DNA cleavage activity in vitro of AgNPs. Overall, our results suggest that AgNPs enhance bacterial resistance to antibiotics by promoting str...