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Inhibitory effect of 405 nm laser light on bacterial biofilm in urethral stent. Sci Rep 2023; 13:3908. [PMID: 36890147 PMCID: PMC9995349 DOI: 10.1038/s41598-023-30280-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 02/20/2023] [Indexed: 03/10/2023] Open
Abstract
The clinical use of urethral stents is usually complicated by various adverse effects, including dysuria, fever, and urinary tract infection (UTI). Biofilms (formed by bacteria, such as Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) adhering to the stent cause UTIs in stented patients (approximately 11%). The undesirable consequences of antibiotics use include bacterial resistance, weight gain, and type 1 diabetes, which occur when antibiotics are used for a long time. We aimed to assess the efficacy of a new optical treatment with a 405 nm laser to inhibit bacterial growth in a urethral stent in vitro. The urethral stent was grown in S. aureus broth media for three days to induce biofilm formation under dynamic conditions. Various irradiation times with the 405 nm laser light were tested (5, 10, and 15 min). The efficacy of the optical treatment on biofilms was evaluated quantitatively and qualitatively. The production of reactive oxygen species helped eliminate the biofilm over the urethral stent after 405 nm irradiation. The inhibition rate corresponded to a 2.2 log reduction of colony-forming units/mL of bacteria after 0.3 W/cm2 of irradiation for 10 min. The treated stent showed a significant reduction in biofilm formation compared with the untreated stent, as demonstrated by SYTO 9 and propidium iodide staining. MTT assays using the CCD-986sk cell line revealed no toxicity after 10 min of irradiation. We conclude that optical treatment with 405 nm laser light inhibits bacterial growth in urethral stents with no or minimal toxicity.
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Role of the flagellar hook in the structural development and antibiotic tolerance of Pseudomonas aeruginosa biofilms. THE ISME JOURNAL 2022; 16:1176-1186. [PMID: 34880458 PMCID: PMC8940932 DOI: 10.1038/s41396-021-01157-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/10/2021] [Accepted: 11/16/2021] [Indexed: 12/16/2022]
Abstract
Pseudomonas aeruginosa biofilms exhibit an intrinsic resistance to antibiotics and constitute a considerable clinical threat. In cystic fibrosis, a common feature of biofilms formed by P. aeruginosa in the airway is the occurrence of mutants deficient in flagellar motility. This study investigates the impact of flagellum deletion on the structure and antibiotic tolerance of P. aeruginosa biofilms, and highlights a role for the flagellum in adaptation and cell survival during biofilm development. Mutations in the flagellar hook protein FlgE influence greatly P. aeruginosa biofilm structuring and antibiotic tolerance. Phenotypic analysis of the flgE knockout mutant compared to the wild type (WT) reveal increased fitness under planktonic conditions, reduced initial adhesion but enhanced formation of microcolony aggregates in a microfluidic environment, and decreased expression of genes involved in exopolysaccharide formation. Biofilm cells of the flgE knock-out mutant display enhanced tolerance towards multiple antibiotics, whereas its planktonic cells show similar resistance to the WT. Confocal microscopy of biofilms demonstrates that gentamicin does not affect the viability of cells located in the inner part of the flgE knock-out mutant biofilms due to reduced penetration. These findings suggest that deficiency in flagellar proteins like FlgE in biofilms and in cystic fibrosis infections represent phenotypic and evolutionary adaptations that alter the structure of P. aeruginosa biofilms conferring increased antibiotic tolerance.
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Live-dead assay on unlabeled cells using phase imaging with computational specificity. Nat Commun 2022; 13:713. [PMID: 35132059 PMCID: PMC8821584 DOI: 10.1038/s41467-022-28214-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 01/11/2022] [Indexed: 12/20/2022] Open
Abstract
Existing approaches to evaluate cell viability involve cell staining with chemical reagents. However, the step of exogenous staining makes these methods undesirable for rapid, nondestructive, and long-term investigation. Here, we present an instantaneous viability assessment of unlabeled cells using phase imaging with computation specificity. This concept utilizes deep learning techniques to compute viability markers associated with the specimen measured by label-free quantitative phase imaging. Demonstrated on different live cell cultures, the proposed method reports approximately 95% accuracy in identifying live and dead cells. The evolution of the cell dry mass and nucleus area for the labeled and unlabeled populations reveal that the chemical reagents decrease viability. The nondestructive approach presented here may find a broad range of applications, from monitoring the production of biopharmaceuticals to assessing the effectiveness of cancer treatments. Common methods for characterising cell viability involve cell staining with chemical reagents. Here the authors report a method for cell viability assessment that does not require labelling; this uses quantitative phase imaging combined with deep learning.
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Straub H, Eberl L, Zinn M, Rossi RM, Maniura-Weber K, Ren Q. A microfluidic platform for in situ investigation of biofilm formation and its treatment under controlled conditions. J Nanobiotechnology 2020; 18:166. [PMID: 33176791 PMCID: PMC7661213 DOI: 10.1186/s12951-020-00724-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/27/2020] [Indexed: 12/20/2022] Open
Abstract
Background Studying bacterial adhesion and early biofilm development is crucial for understanding the physiology of sessile bacteria and forms the basis for the development of novel antimicrobial biomaterials. Microfluidics technologies can be applied in such studies since they permit dynamic real-time analysis and a more precise control of relevant parameters compared to traditional static and flow chamber assays. In this work, we aimed to establish a microfluidic platform that permits real-time observation of bacterial adhesion and biofilm formation under precisely controlled homogeneous laminar flow conditions. Results Using Escherichia coli as the model bacterial strain, a microfluidic platform was developed to overcome several limitations of conventional microfluidics such as the lack of spatial control over bacterial colonization and allow label-free observation of bacterial proliferation at single-cell resolution. This platform was applied to demonstrate the influence of culture media on bacterial colonization and the consequent eradication of sessile bacteria by antibiotic. As expected, the nutrient-poor medium (modified M9 minimal medium) was found to promote bacterial adhesion and to enable a higher adhesion rate compared to the nutrient-rich medium (tryptic soy broth rich medium ). However, in rich medium the adhered cells colonized the glass surface faster than those in poor medium under otherwise identical conditions. For the first time, this effect was demonstrated to be caused by a higher retention of newly generated bacteria in the rich medium, rather than faster growth especially during the initial adhesion phase. These results also indicate that higher adhesion rate does not necessarily lead to faster biofilm formation. Antibiotic treatment of sessile bacteria with colistin was further monitored by fluorescence microscopy at single-cell resolution, allowing in situ analysis of killing efficacy of antimicrobials. Conclusion The platform established here represents a powerful and versatile tool for studying environmental effects such as medium composition on bacterial adhesion and biofilm formation. Our microfluidic setup shows great potential for the in vitro assessment of new antimicrobials and antifouling agents under flow conditions.![]()
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Affiliation(s)
- Hervé Straub
- Laboratory for Biointerfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, 9014, St. Gallen, Switzerland.,Department of Plant and Microbial Biology, University of Zürich, 8008, Zürich, Switzerland
| | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zürich, 8008, Zürich, Switzerland
| | - Manfred Zinn
- Institute of Life Technologies, University of Applied Sciences and Arts Western Switzerland (HES-SO Valais-Wallis), Sion, Switzerland
| | - René M Rossi
- Laboratory for Biomimetic Membranes and Textiles, Empa, Swiss Federal Laboratories for Materials Science and Technology, 9014, St. Gallen, Switzerland
| | - Katharina Maniura-Weber
- Laboratory for Biointerfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, 9014, St. Gallen, Switzerland
| | - Qun Ren
- Laboratory for Biointerfaces, Empa, Swiss Federal Laboratories for Materials Science and Technology, 9014, St. Gallen, Switzerland.
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Xi Q, Hoth-Hannig W, Deng S, Jin X, Fu B, Hannig M. The effect of polyphenol-containing solutions on in situ biofilm formation on enamel and dentin. J Dent 2020; 102:103482. [PMID: 32980427 DOI: 10.1016/j.jdent.2020.103482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/20/2020] [Accepted: 09/22/2020] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVES To investigate the effects of Chinese gallnut extracts and pure tannic acid on in situ biofilm formation on enamel and dentin samples over 24 h. METHODS Bovine enamel and dentin samples were buccally fixed on maxillary splints. Six volunteers wore the splints for 24 h, and rinsed their mouths with tap water (control), 1% tannic acid- and 1% Chinese gallnut extracts-containing solution twice a day, 3 min after the splints were placed in the mouth and before night sleep. Live/dead staining was used for fluorescence microscopic (FM) visualization and quantification of bacteria viability of biofilms formed on enamel and dentin samples. Biofilm coverage was evaluated and recorded by FM and scanning electron microscopy (SEM). In addition, biofilms were analyzed by transmission electron microscopy (TEM). The Kruskal-Wallis test was used to analyze biofilm data. RESULTS Rinsing with tannic acid- and Chinese gallnut extracts-containing solutions significantly reduced in situ biofilm coverage on enamel and dentin samples (P < 0.05). The bacterial viability of biofilms formed on enamel samples was significantly reduced compared to the control (P < 0.05). TEM analysis revealed an increase in pellicle's electron density and thickness and only few or no bacteria adherent to the pellicle in the experimental samples. CONCLUSIONS Rinsing with tannic acid- and Chinese gallnut extracts-containing solutions can effectively inhibit in situ biofilm formation, modify the ultrastructure of biofilms on enamel and dentin surfaces and significantly reduce the bacterial viability of biofilm on enamel surfaces. CLINICAL SIGNIFICANCE Tannic acid- and Chinese gallnut extracts-containing solutions might be used for dental biofilm management.
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Affiliation(s)
- Qingping Xi
- The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, Yan'an Road 395, 310006, Hangzhou, China; Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University School of Stomatology, Kaixuan Road 268, 310020, Hangzhou, China; Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Building 73, Saarland University, D-66421, Homburg, Germany
| | - Wiebke Hoth-Hannig
- Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Building 73, Saarland University, D-66421, Homburg, Germany
| | - Shuli Deng
- The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, Yan'an Road 395, 310006, Hangzhou, China; Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University School of Stomatology, Kaixuan Road 268, 310020, Hangzhou, China
| | - Xiaoting Jin
- The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, Yan'an Road 395, 310006, Hangzhou, China; Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University School of Stomatology, Kaixuan Road 268, 310020, Hangzhou, China
| | - Baiping Fu
- The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, Yan'an Road 395, 310006, Hangzhou, China; Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University School of Stomatology, Kaixuan Road 268, 310020, Hangzhou, China.
| | - Matthias Hannig
- Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Building 73, Saarland University, D-66421, Homburg, Germany.
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Deng Y, Wang L, Chen Y, Long Y. Optimization of staining with SYTO 9/propidium iodide: interplay, kinetics and impact on Brevibacillus brevis. Biotechniques 2020; 69:88-98. [PMID: 32393121 DOI: 10.2144/btn-2020-0036] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Fluorophores SYTO 9 and propidium iodide (PI) are extensively applied in medicine, food industry and environmental monitoring to assess the viability of bacteria. However, the actual performance of these dyes remains largely unknown. In addition, their effects on the physiology of cells have not been elucidated. Here we characterized the effects of these two dyes on Brevibacillus brevis under optimized staining. We found that SYTO 9 entered cells continuously while PI tended to adhere to the cell wall before entering the cell. In addition, results showed that a high amount of the dyes altered the physicochemical properties of membranes, improving their breakthrough. These results provide new perspectives and ideas for improving the characterization of bacterial viability using flow cytometry.
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Affiliation(s)
- Ying Deng
- Guangdong Key Laboratory of Environmental Pollution & Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Lili Wang
- Guangdong Key Laboratory of Environmental Pollution & Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Yujia Chen
- Guangdong Key Laboratory of Environmental Pollution & Health, School of Environment, Jinan University, Guangzhou, 510632, China
| | - Yan Long
- Guangdong Key Laboratory of Environmental Pollution & Health, School of Environment, Jinan University, Guangzhou, 510632, China
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Greenhalgh R, Greenhalgh M, Alshareef F, Robson GD. Application of green fluorescent protein to measure antimicrobial efficacy and the kinetics of cell death against Escherichia coli. J Microbiol Methods 2017; 141:67-72. [DOI: 10.1016/j.mimet.2017.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/31/2017] [Accepted: 08/09/2017] [Indexed: 11/24/2022]
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Rapsch K, Bier FF, Tadros M, von Nickisch-Rosenegk M. Identification of antimicrobial peptides and immobilization strategy suitable for a covalent surface coating with biocompatible properties. Bioconjug Chem 2014; 25:308-19. [PMID: 24372365 DOI: 10.1021/bc4004469] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Bacterial accumulation on solid material displays a major source of biomaterial associated infections, cross contamination, and spreading. To overcome these problems, different investigations on surface modifications for the containment of bacterial adhesion have been done. The aim of this research is the development of a rapid and efficient screening procedure to identify and investigate biologically active peptides in an immobilized state in order to produce an antimicrobial surface coating. We figured out that the antimicrobial mode of action is the most important parameter because only peptides with pronounced membrane disruption abilities displayed meaningful activity in an immobilized state. In addition, we highlighted the influence of the coupling reaction chemistry on the activity and amount of the immobilized peptide. Thereupon we developed an optimized antimicrobial surface coating with unrestricted antimicrobial properties by adjusting the immobilization strategy in combination with lowering the necessary peptide amount. Moreover we demonstrated that this antimicrobial surface coating displayed no cytotoxic activity against a eukaryotic cell line and thereby indicates a promising biocompatibility. Furthermore, different antimicrobial peptides obtained either by chemical peptide synthesis or by recombinant DNA technology were used in this study and their activities as well as their potential applications were discussed.
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Affiliation(s)
- Karsten Rapsch
- Fraunhofer Institute for Biomedical Engineering IBMT, Branch Potsdam , Am Muehlenberg 13, 14476 Potsdam, Germany
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