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Tian S, Shi L, Ren Y, van der Mei HC, Busscher HJ. A normalized parameter for comparison of biofilm dispersants in vitro. Biofilm 2024; 7:100188. [PMID: 38495770 PMCID: PMC10943042 DOI: 10.1016/j.bioflm.2024.100188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/12/2024] [Accepted: 02/28/2024] [Indexed: 03/19/2024] Open
Abstract
Dispersal of infectious biofilms increases bacterial concentrations in blood. To prevent sepsis, the strength of a dispersant should be limited to allow the immune system to remove dispersed bacteria from blood, preferably without antibiotic administration. Biofilm bacteria are held together by extracellular polymeric substances that can be degraded by dispersants. Currently, comparison of the strength of dispersants is not possible by lack of a suitable comparison parameter. Here, a biofilm dispersal parameter is proposed that accounts for differences in initial biofilm properties, dispersant concentration and exposure time by using PBS as a control and normalizing outcomes with respect to concentration and time. The parameter yielded near-identical values based on dispersant-induced reductions in biomass or biofilm colony-forming-units and appeared strain-dependent across pathogens. The parameter as proposed is largely independent of experimental methods and conditions and suitable for comparing different dispersants with respect to different causative strains in particular types of infection.
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Affiliation(s)
- Shuang Tian
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AV, Groningen, the Netherlands
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Functional polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, PR China
| | - Linqi Shi
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Functional polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, PR China
| | - Yijin Ren
- University of Groningen and University Medical Center Groningen, Department of Orthodontics, Hanzeplein 1, 9700, RB, Groningen, the Netherlands
| | - Henny C. van der Mei
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AV, Groningen, the Netherlands
| | - Henk J. Busscher
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AV, Groningen, the Netherlands
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2
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Miller LA, Buckingham-Meyer K, Goeres DM. Simulated aging of draught beer line tubing increases biofilm contamination. Int J Food Microbiol 2024; 415:110630. [PMID: 38401380 DOI: 10.1016/j.ijfoodmicro.2024.110630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 02/13/2024] [Accepted: 02/15/2024] [Indexed: 02/26/2024]
Abstract
Craft brewing is continually gaining popularity in the United States. Craft brewers are committed to producing a wide variety of products and have a vested interest in product quality. Therefore, these brewers have the expectation that the beer poured at the tap will match the quality product that left the brewery. The presence of biofilm in draught lines is hypothesized as a contributing factor when this expectation is not achieved. Clean in place strategies based on the Sinner's Circle of Cleaning are used to remediate organic and inorganic accumulation in beer draught lines, including controlling biofilm accumulation. A study was conducted to determine if repeated exposure to chemical cleaning of vinyl beer tubing impacted biofilm growth, kill/removal, and subsequent regrowth of a mixed species biofilm. The tubing was conditioned to simulate one, two, and five years of use. The data collected demonstrates a clear trend between simulated age of the tubing and biofilm accumulation on the surface. Bacterial log densities ranged from 5.6 Log10(CFU/cm2) for the new tubing to 6.6 Log10(CFU/cm2) for tubing aged to simulate five years of use. The counts for the yeast were similar. Caustic cleaning of the tubing, regardless of starting biofilm coverage, left less than 2.75 Log10(CFU/cm2) viable bacteria and yeast cells remaining on the tubing surface. This demonstrated the effectiveness of the caustic at controlling biofilm accumulation in the simulated beer draught line. The biofilm that accumulated in the five-year aged tubing was able to recover more quickly, reaching 3.6 Log10(CFU/cm2) within 24 h indicating the treatment did not fully eradicate the biofilm, suggesting that the strong chemistry used in this study would cease to be as effective over time.
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Affiliation(s)
- Lindsey A Miller
- Center for Biofilm Engineering, Montana State University, 366 Barnard Hall, Bozeman, MT 59717, United States of America
| | - Kelli Buckingham-Meyer
- Center for Biofilm Engineering, Montana State University, 366 Barnard Hall, Bozeman, MT 59717, United States of America
| | - Darla M Goeres
- Center for Biofilm Engineering, Montana State University, 366 Barnard Hall, Bozeman, MT 59717, United States of America.
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3
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Coandă M, Limban C, Nuță DC. Small Schiff Base Molecules-A Possible Strategy to Combat Biofilm-Related Infections. Antibiotics (Basel) 2024; 13:75. [PMID: 38247634 PMCID: PMC10812491 DOI: 10.3390/antibiotics13010075] [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: 12/13/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/23/2024] Open
Abstract
Microorganisms participating in the development of biofilms exhibit heightened resistance to antibiotic treatment, therefore infections involving biofilms have become a problem in recent years as they are more difficult to treat. Consequently, research efforts are directed towards identifying novel molecules that not only possess antimicrobial properties but also demonstrate efficacy against biofilms. While numerous investigations have focused on antimicrobial capabilities of Schiff bases, their potential as antibiofilm agents remains largely unexplored. Thus, the objective of this article is to present a comprehensive overview of the existing scientific literature pertaining to small molecules categorized as Schiff bases with antibiofilm properties. The survey involved querying four databases (Web of Science, ScienceDirect, Scopus and Reaxys). Relevant articles published in the last 10 years were selected and categorized based on the molecular structure into two groups: classical Schiff bases and oximes and hydrazones. Despite the majority of studies indicating a moderate antibiofilm potential of Schiff bases, certain compounds exhibited a noteworthy effect, underscoring the significance of considering this type of molecular modeling when seeking to develop new molecules with antibiofilm effects.
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Affiliation(s)
| | - Carmen Limban
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Carol Davila University of Medicine and Pharmacy, 6 Traian Vuia Str., 020950 Bucharest, Romania; (M.C.); (D.C.N.)
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4
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Stewart PS, Owkes M. Simulation of catalase-dependent tolerance of microbial biofilm to hydrogen peroxide with a biofilm computer model. NPJ Biofilms Microbiomes 2023; 9:60. [PMID: 37612330 PMCID: PMC10447567 DOI: 10.1038/s41522-023-00426-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 08/07/2023] [Indexed: 08/25/2023] Open
Abstract
Hydrogen peroxide (HP) is a common disinfectant and antiseptic. When applied to a biofilm, it may be expected that the top layer of the biofilm would be killed by HP, the HP would penetrate further, and eventually eradicate the entire biofilm. However, using the Biofilm.jl computer model, we demonstrate a mechanism by which the biofilm can persist, and even become thicker, in the indefinite treatment with an HP solution at concentrations that are lethal to planktonic microorganisms. This surprising result is found to be dependent on the neutralization of HP by dead biomass, which provides protection for living biomass deeper within the biofilm. Practically, to control a biofilm, this result leads to the concept of treating with an HP dose exceeding a critical threshold concentration rather than a sustained, lower-concentration treatment.
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Affiliation(s)
- Philip S Stewart
- Chemical & Biological Engineering, Montana State University, Bozeman, 59717, MT, USA.
| | - Mark Owkes
- Mechanical & Industrial Engineering, Montana State University, Bozeman, 59717, MT, USA.
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5
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Pettygrove BA, Smith HJ, Pallister KB, Voyich JM, Stewart PS, Parker AE. Experimental Designs to Study the Aggregation and Colonization of Biofilms by Video Microscopy With Statistical Confidence. Front Microbiol 2022; 12:785182. [PMID: 35095798 PMCID: PMC8793059 DOI: 10.3389/fmicb.2021.785182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/06/2021] [Indexed: 01/14/2023] Open
Abstract
The goal of this study was to quantify the variability of confocal laser scanning microscopy (CLSM) time-lapse images of early colonizing biofilms to aid in the design of future imaging experiments. To accomplish this a large imaging dataset consisting of 16 independent CLSM microscopy experiments was leveraged. These experiments were designed to study interactions between human neutrophils and single cells or aggregates of Staphylococcus aureus (S. aureus) during the initial stages of biofilm formation. Results suggest that in untreated control experiments, variability differed substantially between growth phases (i.e., lag or exponential). When studying the effect of an antimicrobial treatment (in this case, neutrophil challenge), regardless of the inoculation level or of growth phase, variability changed as a frown-shaped function of treatment efficacy (i.e., the reduction in biofilm surface coverage). These findings were used to predict the best experimental designs for future imaging studies of early biofilms by considering differing (i) numbers of independent experiments; (ii) numbers of fields of view (FOV) per experiment; and (iii) frame capture rates per hour. A spreadsheet capable of assessing any user-specified design is included that requires the expected mean log reduction and variance components from user-generated experimental results. The methodology outlined in this study can assist researchers in designing their CLSM studies of antimicrobial treatments with a high level of statistical confidence.
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Affiliation(s)
- Brian A. Pettygrove
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, United States
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Heidi J. Smith
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, United States
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Kyler B. Pallister
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Jovanka M. Voyich
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Philip S. Stewart
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, United States
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, United States
| | - Albert E. Parker
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, United States
- Department of Mathematical Sciences, Montana State University, Bozeman, MT, United States
- *Correspondence: Albert E. Parker
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6
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Thomas RE, Thomas BC. Reducing Biofilm Infections in Burn Patients' Wounds and Biofilms on Surfaces in Hospitals, Medical Facilities and Medical Equipment to Improve Burn Care: A Systematic Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:13195. [PMID: 34948803 PMCID: PMC8702030 DOI: 10.3390/ijerph182413195] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/08/2021] [Accepted: 12/09/2021] [Indexed: 11/21/2022]
Abstract
Biofilms in burns are major problems: bacterial communities rapidly develop antibiotic resistance, and 60% of burn mortality is attributed to biofilms. Key pathogens are Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and multidrug-resistant Acinetobacter baumanii. Purpose: identify current and novel interventions to reduce biofilms on patients' burns and hospital surfaces and equipment. Medline and Embase were searched without date or language limits, and 31 possible interventions were prioritised: phages, nano-silver, AgSD-NLs@Cur, Acticoat and Mepilex silver, acetic acid, graphene-metal combinations, CuCo2SO4 nanoparticles, Chlorhexidene acetate nanoemulsion, a hydrogel with moxifloxacin, carbomer, Chitosan and Boswellia, LED light therapy with nano-emodin or antimicrobial blue light + Carvacrol to release reactive oxygen species, mannosidase + trypsin, NCK-10 (a napthalene compound with a decyl chain), antimicrobial peptide PV3 (includes two snake venoms), and polypeptides P03 and PL2. Most interventions aimed to penetrate cell membranes and reported significant reductions in biofilms in cfu/mL or biofilm mass or antibiotic minimal inhibitory concentrations or bacterial expression of virulence or quorum sensing genes. Scanning electron microscopy identified important changes in bacterial surfaces. Patients with biofilms need isolating and treating before full admission to hospital. Cleaning and disinfecting needs to include identifying biofilms on keyboards, tablets, cell phones, medical equipment (especially endoscopes), sinks, drains, and kitchens.
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Affiliation(s)
- Roger E. Thomas
- Department of Family Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
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7
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Adjunctive Rifampicin Increases Antibiotic Efficacy in Group A Streptococcal Tissue Infection Models. Antimicrob Agents Chemother 2021; 65:e0065821. [PMID: 34491807 DOI: 10.1128/aac.00658-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilm has recently been highlighted as a complicating feature of necrotizing soft tissue infections (NSTI) caused by Streptococcus pyogenes (i.e., group A Streptococcus [GAS]) contributing to a persistence of bacteria in tissue despite prolonged antibiotic therapy. Here, we assessed the standard treatment of benzylpenicillin and clindamycin with or without rifampin in a tissue-like setting. Antibiotic efficacy was evaluated by CFU determination in a human organotypic skin model infected for 24 or 48 h with GAS strains isolated from NSTI patients. Antibiotic effect was also evaluated by microcalorimetric metabolic assessment in in vitro infections of cellular monolayers providing continuous measurements over time. Adjunctive rifampin resulted in enhanced antibiotic efficacy of bacterial clearance in an organotypic skin tissue model, 97.5% versus 93.9% (P = 0.006). Through microcalorimetric measurements, adjunctive rifampin resulted in decreased metabolic activity and extended lag phase for all clinical GAS strains tested (P < 0.05). In addition, a case report is presented of adjunctive rifampin treatment in an NSTI case with persistent GAS tissue infection. The findings of this study demonstrate that adjunctive rifampin enhances clearance of GAS biofilm in an in vitro tissue infection model.
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8
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Alabresm A, Chandler SL, Benicewicz BC, Decho AW. Nanotargeting of Resistant Infections with a Special Emphasis on the Biofilm Landscape. Bioconjug Chem 2021; 32:1411-1430. [PMID: 34319073 PMCID: PMC8527872 DOI: 10.1021/acs.bioconjchem.1c00116] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Bacterial resistance to antimicrobial compounds is a growing concern in medical and public health circles. Overcoming the adaptable and duplicative resistance mechanisms of bacteria requires chemistry-based approaches. Engineered nanoparticles (NPs) now offer unique advantages toward this effort. However, most in situ infections (in humans) occur as attached biofilms enveloped in a protective surrounding matrix of extracellular polymers, where survival of microbial cells is enhanced. This presents special considerations in the design and deployment of antimicrobials. Here, we review recent efforts to combat resistant bacterial strains using NPs and, then, explore how NP surfaces may be specifically engineered to enhance the potency and delivery of antimicrobial compounds. Special NP-engineering challenges in the design of NPs must be overcome to penetrate the inherent protective barriers of the biofilm and to successfully deliver antimicrobials to bacterial cells. Future challenges are discussed in the development of new antibiotics and their mechanisms of action and targeted delivery via NPs.
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Affiliation(s)
- Amjed Alabresm
- Department of Environmental Health Sciences, University of South Carolina, Columbia, South Carolina 29208, United States
- Department of Biological Development of Shatt Al-Arab & N. Arabian Gulf, Marine Science Centre, University of Basrah, Basrah, Iraq
| | - Savannah L Chandler
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Brian C Benicewicz
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
- USC NanoCenter, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Alan W Decho
- Department of Environmental Health Sciences, University of South Carolina, Columbia, South Carolina 29208, United States
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Johnson E, Petersen T, Goeres DM. Characterizing the Shearing Stresses within the CDC Biofilm Reactor Using Computational Fluid Dynamics. Microorganisms 2021; 9:microorganisms9081709. [PMID: 34442788 PMCID: PMC8399442 DOI: 10.3390/microorganisms9081709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/04/2021] [Accepted: 08/08/2021] [Indexed: 11/21/2022] Open
Abstract
Shearing stresses are known to be a critical factor impacting the growth and physiology of biofilms, but the underlying fluid dynamics within biofilm reactors are rarely well characterized and not always considered when a researcher decides which biofilm reactor to use. The CDC biofilm reactor is referenced in validated Standard Test Methods and US EPA guidance documents. The driving fluid dynamics within the CDC biofilm reactor were investigated using computational fluid dynamics. An unsteady, three-dimensional model of the CDC reactor was simulated at a rotation rate of 125 RPM. The reactor showed turbulent structures, with shear stresses averaging near 0.365 ± 0.074 Pa across all 24 coupons. The pressure variation on the coupon surfaces was found to be larger, with a continuous 2–3 Pa amplitude, coinciding with the baffle passage. Computational fluid dynamics was shown to be a powerful tool for defining key fluid dynamic parameters at a high fidelity within the CDC biofilm reactor. The consistency of the shear stresses and pressures and the unsteadiness of the flow within the CDC reactor may help explain its reproducibility in laboratory studies. The computational model will enable researchers to make an informed decision whether the fluid dynamics present in the CDC biofilm reactor are appropriate for their research.
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Affiliation(s)
- Erick Johnson
- Department Mechanical Engineering, Montana State University, Bozeman, MT 59717, USA; (E.J.); (T.P.)
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, USA
| | - Theodore Petersen
- Department Mechanical Engineering, Montana State University, Bozeman, MT 59717, USA; (E.J.); (T.P.)
| | - Darla M. Goeres
- Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, USA
- Correspondence: ; Tel.: +1-406-994-2440
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10
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Beebout CJ, Sominsky LA, Eberly AR, Van Horn GT, Hadjifrangiskou M. Cytochrome bd promotes Escherichia coli biofilm antibiotic tolerance by regulating accumulation of noxious chemicals. NPJ Biofilms Microbiomes 2021; 7:35. [PMID: 33863914 PMCID: PMC8052454 DOI: 10.1038/s41522-021-00210-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 03/16/2021] [Indexed: 02/02/2023] Open
Abstract
Nutrient gradients in biofilms cause bacteria to organize into metabolically versatile communities capable of withstanding threats from external agents including bacteriophages, phagocytes, and antibiotics. We previously determined that oxygen availability spatially organizes respiration in uropathogenic Escherichia coli biofilms, and that the high-affinity respiratory quinol oxidase cytochrome bd is necessary for extracellular matrix production and biofilm development. In this study we investigate the physiologic consequences of cytochrome bd deficiency in biofilms and determine that loss of cytochrome bd induces a biofilm-specific increase in expression of general diffusion porins, leading to elevated outer membrane permeability. In addition, loss of cytochrome bd impedes the proton mediated efflux of noxious chemicals by diminishing respiratory flux. As a result, loss of cytochrome bd enhances cellular accumulation of noxious chemicals and increases biofilm susceptibility to antibiotics. These results identify an undescribed link between E. coli biofilm respiration and stress tolerance, while suggesting the possibility of inhibiting cytochrome bd as an antibiofilm therapeutic approach.
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Affiliation(s)
- Connor J. Beebout
- grid.412807.80000 0004 1936 9916Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN USA
| | - Levy A. Sominsky
- grid.152326.10000 0001 2264 7217Vanderbilt University, Nashville, TN USA
| | - Allison R. Eberly
- grid.412807.80000 0004 1936 9916Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN USA ,grid.66875.3a0000 0004 0459 167XPresent Address: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | - Gerald T. Van Horn
- grid.412807.80000 0004 1936 9916Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN USA
| | - Maria Hadjifrangiskou
- grid.412807.80000 0004 1936 9916Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN USA ,grid.412807.80000 0004 1936 9916Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN USA
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11
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Legner M, Jonkman J, Swift D. Evaluating the Effects of Disinfectants on Bacterial Biofilms Using a Microfluidics Flow Cell and Time-Lapse Fluorescence Microscopy. Microorganisms 2020; 8:microorganisms8111837. [PMID: 33266442 PMCID: PMC7700140 DOI: 10.3390/microorganisms8111837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 12/03/2022] Open
Abstract
A commercially available microfluidics flow cell was utilized together with widefield fluorescence microscopy to evaluate the effects of disinfectants on bacterial strains. The flow cell’s inner surface supports the formation of biofilms of numerous bacterial species. The modular setup of the flow cell accessories allows connection to syringes, pumps and collection vials, facilitating aseptic experiments in a controlled fluidics environment which can be documented with precisely timed microscopy imaging. The flow cell is inoculated with a suspension of bacteria in a nutrient medium and incubated for several days allowing bacterial cells to form a biofilm. Shortly before performing an assay, the biofilm is labelled with a dual-fluorescent DNA probe which distinguishes unharmed and damaged bacteria. Then a disinfectant sample (or control) is gently injected and time-lapse imaging is used for quantifying the course of bacterial biomass response. We use a simplified widefield microscopy method that allows intensive recording and quantification of time series of two-dimensional frames for tracking the course of disinfectant action on a variety of microbial strains. This procedure has potential for the rapid evaluation of novel products.
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Affiliation(s)
- Milos Legner
- Micrylium Laboratories, Toronto, ON M3H 5T5, Canada;
- Correspondence:
| | - James Jonkman
- Advanced Optical Microscopy Facility, University Health Network, Toronto, ON M5G 1L7, Canada;
| | - Dean Swift
- Micrylium Laboratories, Toronto, ON M3H 5T5, Canada;
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12
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Francolini I, Hall-Stoodley L, Stoodley P. Biofilms, Biomaterials, and Device-Related Infections. Biomater Sci 2020. [DOI: 10.1016/b978-0-12-816137-1.00054-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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13
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Schwarzer S, James GA, Goeres D, Bjarnsholt T, Vickery K, Percival SL, Stoodley P, Schultz G, Jensen SO, Malone M. The efficacy of topical agents used in wounds for managing chronic biofilm infections: A systematic review. J Infect 2019; 80:261-270. [PMID: 31899281 DOI: 10.1016/j.jinf.2019.12.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 12/18/2019] [Accepted: 12/24/2019] [Indexed: 12/19/2022]
Abstract
OBJECTIVES Clinicians have increasingly adopted the widespread use of topical agents to manage chronic wound infections, despite limited data on their effectiveness in vivo. This study sought to evaluate the evidence for commonly employed topical agents used in wounds for the purpose of treating chronic infections caused by biofilm. METHOD We included in vitro, animal and human in vivo studies where topical agents were tested for their efficacy against biofilms, for use in wound care. For human studies, we only included those which utilised appropriate identification techniques for visualising and confirming the presence of biofilms. RESULT A total of 640 articles were identified, with 43 included after meeting eligibility. In vitro testing accounted for 90% (n = 39) of all included studies, five studies using animal models and three human in vivo studies. Sixteen different laboratory models were utilised, with the most frequent being the minimum biofilm eradication concentration (MBEC™) / well plate assay (38%, n = 15 of 39). A total of 44 commercially available topical agents were grouped into twelve categories with the most commonly tested agents being silver, iodine and polyhexamethylene biguanide (PHMB). In vitro results on efficacy demonstrated iodine as having the highest mean log10 reductions of all agents (4.81, ±3.14). CONCLUSION There is large disparity in the translation of laboratory studies to researchers undertaking human trials relating to the effectiveness of commercially available topical agents. There is insufficient human in vivo evidence to definitively recommend any commercially available topical agent over another for the treatment of chronic wound biofilms. The heterogeneity identified between study designs (in vitro to in vivo) further limits the generalisability of results.
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Affiliation(s)
- S Schwarzer
- South West Sydney Limb Preservation and Wound Research, South West Sydney Local Health District, Sydney, Australia.
| | - G A James
- Centre for Biofilm Engineering, Montana State University, Bozeman, MT, United States
| | - D Goeres
- Centre for Biofilm Engineering, Montana State University, Bozeman, MT, United States
| | - T Bjarnsholt
- Department of Immunology and Microbiology, Costerton Biofilm Centre, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Microbiology, Copenhagen University Hospital, Copenhagen, Denmark
| | - K Vickery
- Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney Australia
| | - S L Percival
- 5D Health Protection Group Ltd, Centre of Excellence in Biofilm Science (CEBS), Liverpool Bio-Innovation Hub, Liverpool UK
| | - P Stoodley
- Departments of Microbial Infection and Immunity, and Orthopaedics, Ohio State University, Columbus, OH, United States
| | - G Schultz
- Department of Obstetrics & Gynecology, Institute for Wound Research, University of Florida, Gainesville, FL, United States
| | - S O Jensen
- South West Sydney Limb Preservation and Wound Research, South West Sydney Local Health District, Sydney, Australia; Infectious Diseases and Microbiology, School of Medicine, Ingham Institute for Applied Medical Research, Western Sydney University, United States
| | - M Malone
- South West Sydney Limb Preservation and Wound Research, South West Sydney Local Health District, Sydney, Australia; Infectious Diseases and Microbiology, School of Medicine, Ingham Institute for Applied Medical Research, Western Sydney University, United States
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14
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Conceptual Model of Biofilm Antibiotic Tolerance That Integrates Phenomena of Diffusion, Metabolism, Gene Expression, and Physiology. J Bacteriol 2019; 201:JB.00307-19. [PMID: 31501280 DOI: 10.1128/jb.00307-19] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/28/2019] [Indexed: 01/14/2023] Open
Abstract
Transcriptomic, metabolomic, physiological, and computational modeling approaches were integrated to gain insight into the mechanisms of antibiotic tolerance in an in vitro biofilm system. Pseudomonas aeruginosa biofilms were grown in drip flow reactors on a medium composed to mimic the exudate from a chronic wound. After 4 days, the biofilm was 114 μm thick with 9.45 log10 CFU cm-2 These biofilms exhibited tolerance, relative to exponential-phase planktonic cells, to subsequent treatment with ciprofloxacin. The specific growth rate of the biofilm was estimated via elemental balances to be approximately 0.37 h-1 and with a reaction-diffusion model to be 0.32 h-1, or one-third of the maximum specific growth rate for planktonic cells. Global analysis of gene expression indicated lower transcription of ribosomal genes and genes for other anabolic functions in biofilms than in exponential-phase planktonic cells and revealed the induction of multiple stress responses in biofilm cells, including those associated with growth arrest, zinc limitation, hypoxia, and acyl-homoserine lactone quorum sensing. Metabolic pathways for phenazine biosynthesis and denitrification were transcriptionally activated in biofilms. A customized reaction-diffusion model predicted that steep oxygen concentration gradients will form when these biofilms are thicker than about 40 μm. Mutant strains that were deficient in Psl polysaccharide synthesis, the stringent response, the stationary-phase response, and the membrane stress response exhibited increased ciprofloxacin susceptibility when cultured in biofilms. These results support a sequence of phenomena leading to biofilm antibiotic tolerance, involving oxygen limitation, electron acceptor starvation and growth arrest, induction of associated stress responses, and differentiation into protected cell states.IMPORTANCE Bacteria in biofilms are protected from killing by antibiotics, and this reduced susceptibility contributes to the persistence of infections such as those in the cystic fibrosis lung and chronic wounds. A generalized conceptual model of biofilm antimicrobial tolerance with the following mechanistic steps is proposed: (i) establishment of concentration gradients in metabolic substrates and products; (ii) active biological responses to these changes in the local chemical microenvironment; (iii) entry of biofilm cells into a spectrum of states involving alternative metabolisms, stress responses, slow growth, cessation of growth, or dormancy (all prior to antibiotic treatment); (iv) adaptive responses to antibiotic exposure; and (v) reduced susceptibility of microbial cells to antimicrobial challenges in some of the physiological states accessed through these changes.
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Goeres DM, Walker DK, Buckingham-Meyer K, Lorenz L, Summers J, Fritz B, Goveia D, Dickerman G, Schultz J, Parker AE. Development, standardization, and validation of a biofilm efficacy test: The single tube method. J Microbiol Methods 2019; 165:105694. [DOI: 10.1016/j.mimet.2019.105694] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/17/2019] [Accepted: 08/17/2019] [Indexed: 01/20/2023]
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