Department of Bacterial Genetics, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
J Med Microbiol. 2014 Jun;63(Pt 6):849-854. doi: 10.1099/jmm.0.068833-0. Epub 2014 Mar 12.
The objective of this study was to characterize the effects of silver nanoparticles on Pseudomonas aeruginosa. Their interactions with several conventional antibiotics and ability to induce a stress response were examined. Interactions between silver nanoparticles (AgNPs) and antibiotics against free-living cells and biofilm of P. aeruginosa were studied using the chequerboard method and time-kill assays. The ability of AgNPs to induce a stress response was determined by evaluation of cellular levels of the DnaK and HtpG chaperones using SDS-PAGE and Western blot analysis. Synergistic activity against free-living P. aeruginosa between AgNPs and ampicillin, streptomycin, rifampicin and tetracycline, but not oxacillin, ciprofloxacin, meropenem or ceftazidime, was demonstrated by the chequerboard method. No such interactions were observed against P. aeruginosa biofilm. The results of time-kill assays confirmed synergy only for the AgNPs-streptomycin combination. AgNPs induced the expression of chaperone DnaK. No induction of the HtpG chaperone was detected. In conclusion, AgNPs not only display potent bactericidal activity against P. aeruginosa, but also act synergistically with several conventional antibiotics to enhance their effect against free-living bacteria as determined by the chequerboard method. The time-kill assay proved synergy between AgNPs and streptomycin only. The ability of AgNPs to induce the major chaperone protein DnaK may influence bacterial resistance to antimicrobials.
本研究旨在描述纳米银颗粒对铜绿假单胞菌的影响。考察了其与几种常规抗生素的相互作用以及诱导应激反应的能力。采用棋盘法和时间杀伤试验研究了纳米银颗粒（AgNPs）与抗生素在游离细胞和铜绿假单胞菌生物膜中的相互作用。通过 SDS-PAGE 和 Western blot 分析评估细胞 DnaK 和 HtpG 伴侣蛋白的水平来确定 AgNPs 诱导应激反应的能力。棋盘法显示，AgNPs 与氨苄西林、链霉素、利福平、四环素对游离铜绿假单胞菌表现出协同活性，但与苯唑西林、环丙沙星、美罗培南或头孢他啶无协同作用。时间杀伤试验的结果仅证实了 AgNPs-链霉素组合的协同作用。AgNPs 诱导伴侣蛋白 DnaK 的表达。未检测到 HtpG 伴侣蛋白的诱导。总之，AgNPs 不仅对铜绿假单胞菌表现出强大的杀菌活性，而且还与几种常规抗生素协同作用，通过棋盘法增强其对游离细菌的作用。时间杀伤试验仅证明了 AgNPs 和链霉素之间的协同作用。AgNPs 诱导主要伴侣蛋白 DnaK 的能力可能影响细菌对抗微生物药物的耐药性。
