title: Synergistic effects between silver nanoparticles and antibiotics and the mechanisms involved.
abstract: Silver nanoparticles (nano-Ags), which have well-known antimicrobial properties, are used extensively in various medical and general applications. In this study, the combination effects between nano-Ags and the conventional antibiotics ampicillin, chloramphenicol and kanamycin against various pathogenic bacteria were investigated. The MIC and fractional inhibitory concentration index (FICI) were determined to confirm antibacterial susceptibility and synergistic effects. The results showed that nano-Ags possessed antibacterial effects and synergistic activities. The antibiofilm activities of nano-Ags alone or in combination with antibiotics were also investigated. Formation of biofilm is associated with resistance to antimicrobial agents and chronic bacterial infections. The results indicated that nano-Ags also had antibiofilm activities. To understand these effects of nano-Ags, an ATPase inhibitor assay, permeability assay and hydroxyl radical assay were conducted. The antibacterial activity of nano-Ags was influenced by ATP-associated metabolism rather than by the permeability of the outer membrane. Additionally, nano-Ags generated hydroxyl radicals, a highly reactive oxygen species induced by bactericidal agents. It was concluded that nano-Ags have potential as a combination therapeutic agent for the treatment of infectious diseases by bacteria.
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daehak-ro 80 Buk-gu Daegu, 702-701, Republic of Korea.
authors.forename: In-Sok
authors.initials: IS
authors.lastname: Hwang
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daehak-ro 80 Buk-gu Daegu, 702-701, Republic of Korea.
authors.forename: Ji Hong
authors.initials: JH
authors.lastname: Hwang
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daehak-ro 80 Buk-gu Daegu, 702-701, Republic of Korea.
authors.forename: Hyemin
authors.initials: H
authors.lastname: Choi
authors.affiliation: Department of Clinical Pathology, Tae Kyeung College, 24, Danbuk-ri, Jain-myeon, Gyeongsan-si, Gyeongsangbuk-do, 712-719, Republic of Korea.
authors.forename: Keuk-Jun
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daehak-ro 80 Buk-gu Daegu, 702-701, Republic of Korea.
authors.forename: Dong Gun
authors.initials: DG
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D004357:Drug Synergism; D016984:Enterococcus faecium / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D053768:Metal Nanoparticles; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012834:Silver / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects; D013295:Streptococcus mutans / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D012834:Silver