Enhancing Antibacterial Efficacy: Combining Novel Bacterial Topoisomerase Inhibitors with Efflux Pump Inhibitors and Other Agents Against Gram-Negative Bacteria
Maša Zorman,
Maja Kokot,
Irena Zdovc,
Lidija Senerovic,
Mina Mandic,
Nace Zidar,
Andrej Emanuel Cotman,
Martina Durcik,
Lucija Peterlin Mašič,
Nikola Minovski,
Marko Anderluh,
Martina Hrast Rambaher
Affiliations
Maša Zorman
Theory Department, Laboratory for Cheminformatics, National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia
Maja Kokot
Theory Department, Laboratory for Cheminformatics, National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia
Irena Zdovc
Institute of Microbiology and Parasitology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia
Lidija Senerovic
Laboratory for Microbial Molecular Genetics and Ecology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia
Mina Mandic
Laboratory for Microbial Molecular Genetics and Ecology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11042 Belgrade, Serbia
Nace Zidar
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000 Ljubljana, Slovenia
Andrej Emanuel Cotman
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000 Ljubljana, Slovenia
Martina Durcik
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000 Ljubljana, Slovenia
Lucija Peterlin Mašič
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000 Ljubljana, Slovenia
Nikola Minovski
Theory Department, Laboratory for Cheminformatics, National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia
Marko Anderluh
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000 Ljubljana, Slovenia
Martina Hrast Rambaher
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000 Ljubljana, Slovenia
Background: The novel bacterial topoisomerase inhibitors (NBTIs) developed in our laboratory show potent on-target enzyme inhibition but suffer from low activity against Gram-negative bacteria. Methods: With the aim of improving the antibacterial activity of our compounds against Gram-negative bacteria, we tested them in combination with different efflux pump inhibitors (EPIs), a strategy that showed promise in several other classes of antimicrobials. We also investigated the combined effect of NBTIs with ATP-competitive inhibitors of bacterial type II topoisomerases (ACIs), as well as the antibiofilm properties of our compounds and the combination with EPIs against early and mature Acietobacter baumannii biofilm. Results: Our results demonstrate that combinations of NBTIs with EPI Phenylalanine-arginyl-β-naphthylamide significantly reduce the corresponding NBTIs’ minimal inhibitory concentration values and show potentiation of A. baumannii biofilm inhibition as compared to NBTIs alone. Although combinations of NBITs and ACIs did not show synergistic effects, the FIC index value calculations revealed additive effects for all the combinations of a selected NBTI in combination with three ACIs in all the assayed Gram-negative bacteria from the ESKAPE group. Conclusions: These results show for the first time that combinations of NBTIs with either EPIs or a different class of the topoisomerase inhibitors may be a beneficial strategy to combat difficult-to-treat bacterial infections.
