title: Enhanced antibacterial effect of antibiotics in combination with silver nanoparticles against animal pathogens.
abstract: Antibiotic resistant bacteria are a serious health risk in both human and veterinary medicine. Several studies have shown that silver nanoparticles (AgNPs) exert a high level of antibacterial activity against antibiotic resistant strains in humans. The aim of this study was to evaluate the antibacterial effects of a combined therapy of AgNPs and antibiotics against veterinary bacteria that show resistance to antibiotics. A microdilution checkerboard method was used to determine the minimal inhibitory concentrations of both types of antimicrobials, alone and in combination. The fractional inhibitory concentration index was calculated and used to classify observed collective antibacterial activity as synergistic, additive (only the sum of separate effects of drugs), indifferent (no effect) or antagonistic. From the 40 performed tests, seven were synergistic, 17 additive and 16 indifferent. None of the tested combinations showed an antagonistic effect. The majority of synergistic effects were observed for combinations of AgNPs given together with gentamicin, but the highest enhancement of antibacterial activity was found with combined therapy together with penicillin G against Actinobacillus pleuropneumoniae. A. pleuropneumoniae and Pasteurella multocida originally resistant to amoxycillin, gentamicin and colistin were sensitive to these antibiotics when combined with AgNPs. The study shows that AgNPs have potential as adjuvants for the treatment of animal bacterial diseases.
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17 Listopadu 12, 771 46 Olomouc, Czech Republic.
authors.forename: Monika
authors.initials: M
authors.lastname: Smekalova
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Aragon
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17 Listopadu 12, 771 46 Olomouc, Czech Republic. Electronic address: ales.panacek@upol.cz.
authors.forename: Ales
authors.initials: A
authors.lastname: Panacek
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17 Listopadu 12, 771 46 Olomouc, Czech Republic.
authors.forename: Robert
authors.initials: R
authors.lastname: Prucek
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17 Listopadu 12, 771 46 Olomouc, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Zboril
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17 Listopadu 12, 771 46 Olomouc, Czech Republic.
authors.forename: Libor
authors.initials: L
authors.lastname: Kvitek
mesh_terms: D000277:Adjuvants, Pharmaceutic / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000188:drug therapy*; D004357:Drug Synergism; D053768:Metal Nanoparticles; D012834:Silver / Q000494:pharmacology* / Q000627:therapeutic use*
chemical_list: D000277:Adjuvants, Pharmaceutic; D000900:Anti-Bacterial Agents; D012834:Silver
keywords: Antibacterial activity; Bacterial resistance; Silver nanoparticles; Synergy