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Freire TFA, Hu Z, Wood KB, Gjini E. Modeling spatial evolution of multi-drug resistance under drug environmental gradients. PLoS Comput Biol 2024; 20:e1012098. [PMID: 38820350 PMCID: PMC11142541 DOI: 10.1371/journal.pcbi.1012098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 04/23/2024] [Indexed: 06/02/2024] Open
Abstract
Multi-drug combinations to treat bacterial populations are at the forefront of approaches for infection control and prevention of antibiotic resistance. Although the evolution of antibiotic resistance has been theoretically studied with mathematical population dynamics models, extensions to spatial dynamics remain rare in the literature, including in particular spatial evolution of multi-drug resistance. In this study, we propose a reaction-diffusion system that describes the multi-drug evolution of bacteria based on a drug-concentration rescaling approach. We show how the resistance to drugs in space, and the consequent adaptation of growth rate, is governed by a Price equation with diffusion, integrating features of drug interactions and collateral resistances or sensitivities to the drugs. We study spatial versions of the model where the distribution of drugs is homogeneous across space, and where the drugs vary environmentally in a piecewise-constant, linear and nonlinear manner. Although in many evolution models, per capita growth rate is a natural surrogate for fitness, in spatially-extended, potentially heterogeneous habitats, fitness is an emergent property that potentially reflects additional complexities, from boundary conditions to the specific spatial variation of growth rates. Applying concepts from perturbation theory and reaction-diffusion equations, we propose an analytical metric for characterization of average mutant fitness in the spatial system based on the principal eigenvalue of our linear problem, λ1. This enables an accurate translation from drug spatial gradients and mutant antibiotic susceptibility traits to the relative advantage of each mutant across the environment. Our approach allows one to predict the precise outcomes of selection among mutants over space, ultimately from comparing their λ1 values, which encode a critical interplay between growth functions, movement traits, habitat size and boundary conditions. Such mathematical understanding opens new avenues for multi-drug therapeutic optimization.
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Affiliation(s)
- Tomas Ferreira Amaro Freire
- Center for Computational and Stochastic Mathematics, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
| | - Zhijian Hu
- Departments of Biophysics and Physics, University of Michigan, United States of America
| | - Kevin B. Wood
- Departments of Biophysics and Physics, University of Michigan, United States of America
| | - Erida Gjini
- Center for Computational and Stochastic Mathematics, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
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Freire T, Hu Z, Wood KB, Gjini E. Modeling spatial evolution of multi-drug resistance under drug environmental gradients. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.16.567447. [PMID: 38014279 PMCID: PMC10680811 DOI: 10.1101/2023.11.16.567447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Multi-drug combinations to treat bacterial populations are at the forefront of approaches for infection control and prevention of antibiotic resistance. Although the evolution of antibiotic resistance has been theoretically studied with mathematical population dynamics models, extensions to spatial dynamics remain rare in the literature, including in particular spatial evolution of multi-drug resistance. In this study, we propose a reaction-diffusion system that describes the multi-drug evolution of bacteria, based on a rescaling approach (Gjini and Wood, 2021). We show how the resistance to drugs in space, and the consequent adaptation of growth rate is governed by a Price equation with diffusion. The covariance terms in this equation integrate features of drug interactions and collateral resistances or sensitivities to the drugs. We study spatial versions of the model where the distribution of drugs is homogeneous across space, and where the drugs vary environmentally in a piecewise-constant, linear and nonlinear manner. Applying concepts from perturbation theory and reaction-diffusion equations, we propose an analytical characterization of average mutant fitness in the spatial system based on the principal eigenvalue of our linear problem. This enables an accurate translation from drug spatial gradients and mutant antibiotic susceptibility traits, to the relative advantage of each mutant across the environment. Such a mathematical understanding allows to predict the precise outcomes of selection over space, ultimately from the fundamental balance between growth and movement traits, and their diversity in a population.
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Affiliation(s)
- Tomas Freire
- Center for Computational and Stochastic Mathematics, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
| | - Zhijian Hu
- Departments of Biophysics and Physics, University of Michigan, USA
| | - Kevin B. Wood
- Departments of Biophysics and Physics, University of Michigan, USA
| | - Erida Gjini
- Center for Computational and Stochastic Mathematics, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
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Sinclair P, Brackley CA, Carballo-Pacheco M, Allen RJ. Model for Quorum-Sensing Mediated Stochastic Biofilm Nucleation. PHYSICAL REVIEW LETTERS 2022; 129:198102. [PMID: 36399746 DOI: 10.1103/physrevlett.129.198102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
Surface-attached bacterial biofilms cause disease and industrial biofouling, as well as being widespread in the natural environment. Density-dependent quorum sensing is one of the mechanisms implicated in biofilm initiation. Here we present and analyze a model for quorum-sensing triggered biofilm initiation. In our model, individual, planktonic bacteria adhere to a surface, proliferate, and undergo a collective transition to a biofilm phenotype. This model predicts a stochastic transition between a loosely attached, finite layer of bacteria near the surface and a growing biofilm. The transition is governed by two key parameters: the collective transition density relative to the carrying capacity and the immigration rate relative to the detachment rate. Biofilm initiation is complex, but our model suggests that stochastic nucleation phenomena may be relevant.
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Affiliation(s)
- Patrick Sinclair
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Chris A Brackley
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Martín Carballo-Pacheco
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Rosalind J Allen
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
- Theoretical Microbial Ecology, Faculty of Biological Sciences, Institute of Microbiology, Friedrich Schiller University Jena, Buchaer Strasse 6, 07745 Jena, Germany
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Sinclair P, Longyear J, Reynolds K, Finnie AA, Brackley CA, Carballo-Pacheco M, Allen RJ. A computational model for microbial colonization of an antifouling surface. Front Microbiol 2022; 13:920014. [PMID: 36238597 PMCID: PMC9551280 DOI: 10.3389/fmicb.2022.920014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/01/2022] [Indexed: 11/13/2022] Open
Abstract
Biofouling of marine surfaces such as ship hulls is a major industrial problem. Antifouling (AF) paints delay the onset of biofouling by releasing biocidal chemicals. We present a computational model for microbial colonization of a biocide-releasing AF surface. Our model accounts for random arrival from the ocean of microorganisms with different biocide resistance levels, biocide-dependent proliferation or killing, and a transition to a biofilm state. Our computer simulations support a picture in which biocide-resistant microorganisms initially form a loosely attached layer that eventually transitions to a growing biofilm. Once the growing biofilm is established, immigrating microorganisms are shielded from the biocide, allowing more biocide-susceptible strains to proliferate. In our model, colonization of the AF surface is highly stochastic. The waiting time before the biofilm establishes is exponentially distributed, suggesting a Poisson process. The waiting time depends exponentially on both the concentration of biocide at the surface and the rate of arrival of resistant microorganisms from the ocean. Taken together our results suggest that biofouling of AF surfaces may be intrinsically stochastic and hence unpredictable, but immigration of more biocide-resistant species, as well as the biological transition to biofilm physiology, may be important factors controlling the time to biofilm establishment.
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Affiliation(s)
- Patrick Sinclair
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Jennifer Longyear
- Marine, Protective and Yacht Coatings, International Paint Ltd, AkzoNobel, Gateshead, United Kingdom
| | - Kevin Reynolds
- Marine, Protective and Yacht Coatings, International Paint Ltd, AkzoNobel, Gateshead, United Kingdom
| | - Alistair A. Finnie
- Marine, Protective and Yacht Coatings, International Paint Ltd, AkzoNobel, Gateshead, United Kingdom
| | - Chris A. Brackley
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Rosalind J. Allen
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
- Theoretical Microbial Ecology, Institute of Microbiology, Faculty of Biological Sciences, Friedrich-Schiller University Jena, Jena, Germany
- *Correspondence: Rosalind J. Allen
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Caldara M, Belgiovine C, Secchi E, Rusconi R. Environmental, Microbiological, and Immunological Features of Bacterial Biofilms Associated with Implanted Medical Devices. Clin Microbiol Rev 2022; 35:e0022120. [PMID: 35044203 PMCID: PMC8768833 DOI: 10.1128/cmr.00221-20] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The spread of biofilms on medical implants represents one of the principal triggers of persistent and chronic infections in clinical settings, and it has been the subject of many studies in the past few years, with most of them focused on prosthetic joint infections. We review here recent works on biofilm formation and microbial colonization on a large variety of indwelling devices, ranging from heart valves and pacemakers to urological and breast implants and from biliary stents and endoscopic tubes to contact lenses and neurosurgical implants. We focus on bacterial abundance and distribution across different devices and body sites and on the role of environmental features, such as the presence of fluid flow and properties of the implant surface, as well as on the interplay between bacterial colonization and the response of the human immune system.
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Affiliation(s)
- Marina Caldara
- Interdepartmental Center on Safety, Technologies, and Agri-food Innovation (SITEIA.PARMA), University of Parma, Parma, Italy
| | - Cristina Belgiovine
- IRCCS Humanitas Research Hospital, Rozzano–Milan, Italy
- Scuola di Specializzazione in Microbiologia e Virologia, Università degli Studi di Pavia, Pavia, Italy
| | - Eleonora Secchi
- Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
| | - Roberto Rusconi
- IRCCS Humanitas Research Hospital, Rozzano–Milan, Italy
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele–Milan, Italy
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Impacts of Magnetic Immobilization on the Growth and Metabolic Status of Recombinant Pichia pastoris. Mol Biotechnol 2021; 64:320-329. [PMID: 34647242 DOI: 10.1007/s12033-021-00420-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 10/10/2021] [Indexed: 10/20/2022]
Abstract
Downstream processing is an expensive step for industrial production of recombinant proteins. Cell immobilization is known as one of the ideal solutions in regard to process intensification. In recent years, magnetic immobilization was introduced as a new technique for cell immobilization. This technique was successfully employed to harvest many bacterial and eukaryotic cells. But there are no data about the influence of magnetic immobilization on the eukaryotic inducted recombinant cells. In this study, impacts of magnetic immobilization on the growth and metabolic status of induced recombinant Pichia pastoris as a valuable eukaryotic model cells were investigated. Results based on colony-forming unit, OD600, and trypan blue assay indicated that magnetic immobilization had no adverse effect on the growth and viability of P. pastoris cells. Also, about 20-40% increase in metabolic activity was recorded in immobilized cells that were decorated with 0.5-2 mg/mL nanoparticles. Total protein and carbohydrate of the cells were also measured as main indicatives for cell function and no significant changes were observed in the immobilized cells. Current data show magnetic immobilization as a biocompatible technique for application in eukaryotic expression systems. Results can be considered for further developments in P. pastoris-based expression systems.
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Fuentes-Hernández A, Hernández-Koutoucheva A, Muñoz AF, Domínguez Palestino R, Peña-Miller R. Diffusion-driven enhancement of the antibiotic resistance selection window. J R Soc Interface 2019; 16:20190363. [PMID: 31506045 DOI: 10.1098/rsif.2019.0363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The current crisis of antimicrobial resistance in clinically relevant pathogens has highlighted our limited understanding of the ecological and evolutionary forces that drive drug resistance adaptation. For instance, although human tissues are highly heterogeneous, most of our mechanistic understanding about antibiotic resistance evolution is based on constant and well-mixed environmental conditions. A consequence of considering spatial heterogeneity is that, even if antibiotics are prescribed at high dosages, the penetration of drug molecules through tissues inevitably produces antibiotic gradients, exposing bacterial populations to a range of selective pressures and generating a dynamic fitness landscape that changes in space and time. In this paper, we will use a combination of mathematical modelling and computer simulations to study the population dynamics of susceptible and resistant strains competing for resources in a network of micro-environments with varying degrees of connectivity. Our main result is that highly connected environments increase diffusion of drug molecules, enabling resistant phenotypes to colonize a larger number of spatial locations. We validated this theoretical result by culturing fluorescently labelled Escherichia coli in 3D-printed devices that allow us to control the rate of diffusion of antibiotics between neighbouring compartments and quantify the spatio-temporal distribution of resistant and susceptible bacterial cells.
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Affiliation(s)
- Ayari Fuentes-Hernández
- Laboratorio de Biología Sintética y de Sistemas, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Mexico
| | - Anastasia Hernández-Koutoucheva
- Laboratorio de Biología Sintética y de Sistemas, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Mexico
| | - Alán F Muñoz
- Laboratorio de Biología Sintética y de Sistemas, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Mexico
| | - Raúl Domínguez Palestino
- Laboratorio de Biología Sintética y de Sistemas, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Mexico
| | - Rafael Peña-Miller
- Laboratorio de Biología Sintética y de Sistemas, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Mexico
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