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Exposure of Salmonella biofilms to antibiotic concentrations rapidly selects resistance with collateral tradeoffs. NPJ Biofilms Microbiomes 2021; 7:3. [PMID: 33431848 PMCID: PMC7801651 DOI: 10.1038/s41522-020-00178-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 12/10/2020] [Indexed: 12/18/2022] Open
Abstract
Most bacteria in nature exist in biofilms, which are inherently tolerant to antibiotics. There is currently very limited understanding of how biofilms evolve in response to sub-lethal concentrations of antimicrobials. In this study, we use a biofilm evolution model to study the effects of sub-inhibitory concentrations of three antibiotics on Salmonella Typhimurium biofilms. We show that biofilms rapidly evolve resistance to each antibiotic they are exposed to, demonstrating a strong selective pressure on biofilms from low antibiotic concentrations. While all antibiotics tested select for clinical resistance, there is no common mechanism. Adaptation to antimicrobials, however, has a marked cost for other clinically important phenotypes, including biofilm formation and virulence. Cefotaxime selects mutants with the greatest deficit in biofilm formation followed by azithromycin and then ciprofloxacin. Understanding the impacts of exposure of biofilms to antibiotics will help understand evolutionary trajectories and may help guide how best to use antibiotics in a biofilm context. Experimental evolution in combination with whole-genome sequencing is a powerful tool for the prediction of evolution trajectories associated with antibiotic resistance in biofilms.
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Balázs VL, Horváth B, Kerekes E, Ács K, Kocsis B, Varga A, Böszörményi A, Nagy DU, Krisch J, Széchenyi A, Horváth G. Anti- Haemophilus Activity of Selected Essential Oils Detected by TLC-Direct Bioautography and Biofilm Inhibition. Molecules 2019; 24:molecules24183301. [PMID: 31514307 PMCID: PMC6767207 DOI: 10.3390/molecules24183301] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/05/2019] [Accepted: 09/10/2019] [Indexed: 01/31/2023] Open
Abstract
Essential oils (EOs) are becoming increasingly popular in medical applications because of their antimicrobial effect. Direct bioautography (DB) combined with thin layer chromatography (TLC) is a screening method for the detection of antimicrobial compounds in plant extracts, for example, in EOs. Due to their lipophilic character, the common microbiological assays (etc. disk diffusion) could not provide reliable results. The aim of this study was the evaluation of antibacterial and anti-biofilm properties of the EO of cinnamon bark, clove, peppermint, thyme, and their main components against Haemophilus influenzae and H. parainfluenzae. Oil in water (O/W) type Pickering nano-emulsions stabilized with silica nanoparticles from each oil were prepared to increase their water-solubility. Samples with Tween80 surfactant and absolute ethanol were also used. Results showed that H. influenzae was more sensitive to the EOs than H. parainfluenzae (except for cinnamon bark oil). In thin layer chromatography-direct bioautography (TLC-DB) the ethanolic solutions of thyme oil presented the best activity against H. influenzae, while cinnamon oil was the most active against H. parainfluenzae. Pickering nano-emulsion of cinnamon oil inhibited the biofilm formation of H. parainfluenzae (76.35%) more efficiently than samples with Tween80 surfactant or absolute ethanol. In conclusion, Pickering nano-emulsion of EOs could inhibit the biofilm production effectively.
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Affiliation(s)
- Viktória Lilla Balázs
- Department of Pharmacognosy, Faculty of Pharmacy, University of Pécs, H-7624 Pécs, Hungary; (V.L.B.)
| | - Barbara Horváth
- Institute of Pharmaceutical Technology and Biopharmacy, Faculty of Pharmacy, University of Pécs, H-7624 Pécs, Hungary; (B.H.); (A.S.)
| | - Erika Kerekes
- Department of Microbiology, Faculty of Science and Informatics, University of Szeged, H-6726 Szeged, Hungary;
| | - Kamilla Ács
- Department of Pharmacognosy, Faculty of Pharmacy, University of Pécs, H-7624 Pécs, Hungary; (V.L.B.)
| | - Béla Kocsis
- Department of Medical Microbiology and Immunology, Medical School, University of Pécs, H-7624 Pécs, Hungary; (B.K.); (A.V.)
| | - Adorján Varga
- Department of Medical Microbiology and Immunology, Medical School, University of Pécs, H-7624 Pécs, Hungary; (B.K.); (A.V.)
| | - Andrea Böszörményi
- Institute of Pharmacognosy, Faculty of Pharmacy, Semmelweis University, H-1085 Budapest, Hungary;
| | - Dávid U. Nagy
- Department of Genetics and Molecular Biology, Institute of Biology, Faculty of Sciences, University of Pécs, H-7624 Pécs, Hungary;
| | - Judit Krisch
- Department of Food Engineering, Faculty of Engineering, University of Szeged, H-6724 Szeged, Hungary;
| | - Aleksandar Széchenyi
- Institute of Pharmaceutical Technology and Biopharmacy, Faculty of Pharmacy, University of Pécs, H-7624 Pécs, Hungary; (B.H.); (A.S.)
| | - Györgyi Horváth
- Department of Pharmacognosy, Faculty of Pharmacy, University of Pécs, H-7624 Pécs, Hungary; (V.L.B.)
- Correspondence: ; Tel.: +36-72-503-625 (ext. 28823)
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