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Abstract
The gut microbiota prevents infection by crowding out pathogens.
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Affiliation(s)
- Lauren C Radlinski
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA, USA
| | - Andreas J Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA, USA
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2
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Abstract
Listeria monocytogenes uses respiration to sustain a risky fermentative lifestyle during infection.
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Affiliation(s)
- Lauren C Radlinski
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, United States
| | - Andreas J Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, United States
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3
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Abstract
Aminoglycosides are bactericidal drugs which require a proton motive force (PMF) for uptake into the bacterial cell. Low energy cells, such as persisters, maintain a PMF below the threshold for drug uptake and are tolerant to aminoglycosides. In this chapter, we discuss mechanisms to target the bacterial membrane and stimulate aminoglycoside uptake to kill Staphylococcus aureus persisters.
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Affiliation(s)
- Ashelyn E Sidders
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lauren C Radlinski
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah E Rowe
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Brian P Conlon
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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4
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Zalis EA, Nuxoll AS, Manuse S, Clair G, Radlinski LC, Conlon BP, Adkins J, Lewis K. Stochastic Variation in Expression of the Tricarboxylic Acid Cycle Produces Persister Cells. mBio 2019; 10:e01930-19. [PMID: 31530676 PMCID: PMC6751062 DOI: 10.1128/mbio.01930-19] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 08/05/2019] [Indexed: 02/07/2023] Open
Abstract
Chronic bacterial infections are difficult to eradicate, though they are caused primarily by drug-susceptible pathogens. Antibiotic-tolerant persisters largely account for this paradox. In spite of their significance in the recalcitrance of chronic infections, the mechanism of persister formation is poorly understood. We previously reported that a decrease in ATP levels leads to drug tolerance in Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus We reasoned that stochastic fluctuation in the expression of tricarboxylic acid (TCA) cycle enzymes can produce cells with low energy levels. S. aureus knockouts in glutamate dehydrogenase, 2-oxoketoglutarate dehydrogenase, succinyl coenzyme A (CoA) synthetase, and fumarase have low ATP levels and exhibit increased tolerance of fluoroquinolone, aminoglycoside, and β-lactam antibiotics. Fluorescence-activated cell sorter (FACS) analysis of TCA genes shows a broad Gaussian distribution in a population, with differences of over 3 orders of magnitude in the levels of expression between individual cells. Sorted cells with low levels of TCA enzyme expression have an increased tolerance of antibiotic treatment. These findings suggest that fluctuations in the levels of expression of energy-generating components serve as a mechanism of persister formation.IMPORTANCE Persister cells are rare phenotypic variants that are able to survive antibiotic treatment. Unlike resistant bacteria, which have specific mechanisms to prevent antibiotics from binding to their targets, persisters evade antibiotic killing by entering a tolerant nongrowing state. Persisters have been implicated in chronic infections in multiple species, and growing evidence suggests that persister cells are responsible for many cases of antibiotic treatment failure. New antibiotic treatment strategies aim to kill tolerant persister cells more effectively, but the mechanism of tolerance has remained unclear until now.
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Affiliation(s)
- Eliza A Zalis
- Department of Biology, Antimicrobial Discovery Center, Northeastern University, Boston, Massachusetts, USA
| | - Austin S Nuxoll
- Department of Biology, Antimicrobial Discovery Center, Northeastern University, Boston, Massachusetts, USA
| | - Sylvie Manuse
- Department of Biology, Antimicrobial Discovery Center, Northeastern University, Boston, Massachusetts, USA
| | - Geremy Clair
- Biological Sciences, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Lauren C Radlinski
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Brian P Conlon
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Joshua Adkins
- Biological Sciences, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Kim Lewis
- Department of Biology, Antimicrobial Discovery Center, Northeastern University, Boston, Massachusetts, USA
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5
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Radlinski LC, Rowe SE, Brzozowski R, Wilkinson AD, Huang R, Eswara P, Conlon BP. Chemical Induction of Aminoglycoside Uptake Overcomes Antibiotic Tolerance and Resistance in Staphylococcus aureus. Cell Chem Biol 2019; 26:1355-1364.e4. [PMID: 31402316 DOI: 10.1016/j.chembiol.2019.07.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/01/2019] [Accepted: 07/22/2019] [Indexed: 01/13/2023]
Abstract
Aminoglycoside antibiotics require proton motive force (PMF) for bacterial internalization. In non-respiring populations, PMF drops below the level required for drug influx, limiting the utility of aminoglycosides against strict and facultative anaerobes. We recently demonstrated that rhamnolipids (RLs), biosurfactant molecules produced by Pseudomonas aeruginosa, potentiate aminoglycoside activity against Staphylococcus aureus. Here, we demonstrate that RLs induce PMF-independent aminoglycoside uptake to restore sensitivity to otherwise tolerant persister, biofilm, small colony variant, and anaerobic populations of S. aureus. Furthermore, we show that this approach represses the rise of resistance, restores sensitivity to highly resistant clinical isolates, and is effective against other Gram-positive pathogens. Finally, while other membrane-acting agents can synergize with aminoglycosides, induction of PMF-independent uptake is uncommon, and distinct to RLs among several compounds tested. In all, small-molecule induction of PMF-independent aminoglycoside uptake circumvents phenotypic tolerance, overcomes genotypic resistance, and expands the utility of aminoglycosides against intrinsically recalcitrant bacterial populations.
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Affiliation(s)
- Lauren C Radlinski
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sarah E Rowe
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Robert Brzozowski
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA
| | - Alec D Wilkinson
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rennica Huang
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Prahathees Eswara
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA
| | - Brian P Conlon
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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6
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Radlinski LC, Brunton J, Steele S, Taft-Benz S, Kawula TH. Defining the Metabolic Pathways and Host-Derived Carbon Substrates Required for Francisella tularensis Intracellular Growth. mBio 2018; 9:e01471-18. [PMID: 30459188 PMCID: PMC6247087 DOI: 10.1128/mbio.01471-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/05/2018] [Indexed: 12/13/2022] Open
Abstract
Francisella tularensis is a Gram-negative, facultative, intracellular bacterial pathogen and one of the most virulent organisms known. A hallmark of F. tularensis pathogenesis is the bacterium's ability to replicate to high densities within the cytoplasm of infected cells in over 250 known host species, including humans. This demonstrates that F. tularensis is adept at modulating its metabolism to fluctuating concentrations of host-derived nutrients. The precise metabolic pathways and nutrients utilized by F. tularensis during intracellular growth, however, are poorly understood. Here, we use systematic mutational analysis to identify the carbon catabolic pathways and host-derived nutrients required for F. tularensis intracellular replication. We demonstrate that the glycolytic enzyme phosphofructokinase (PfkA), and thus glycolysis, is dispensable for F. tularensis SchuS4 virulence, and we highlight the importance of the gluconeogenic enzyme fructose 1,6-bisphosphatase (GlpX). We found that the specific gluconeogenic enzymes that function upstream of GlpX varied based on infection model, indicating that F. tularensis alters its metabolic flux according to the nutrients available within its replicative niche. Despite this flexibility, we found that glutamate dehydrogenase (GdhA) and glycerol 3-phosphate (G3P) dehydrogenase (GlpA) are essential for F. tularensis intracellular replication in all infection models tested. Finally, we demonstrate that host cell lipolysis is required for F. tularensis intracellular proliferation, suggesting that host triglyceride stores represent a primary source of glycerol during intracellular replication. Altogether, the data presented here reveal common nutritional requirements for a bacterium that exhibits characteristic metabolic flexibility during infection.IMPORTANCE The widespread onset of antibiotic resistance prioritizes the need for novel antimicrobial strategies to prevent the spread of disease. With its low infectious dose, broad host range, and high rate of mortality, F. tularensis poses a severe risk to public health and is considered a potential agent for bioterrorism. F. tularensis reaches extreme densities within the host cell cytosol, often replicating 1,000-fold in a single cell within 24 hours. This remarkable rate of growth demonstrates that F. tularensis is adept at harvesting and utilizing host cell nutrients. However, like most intracellular pathogens, the types of nutrients utilized by F. tularensis and how they are acquired is not fully understood. Identifying the essential pathways for F. tularensis replication may reveal new therapeutic strategies for targeting this highly infectious pathogen and may provide insight for improved targeting of intracellular pathogens in general.
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Affiliation(s)
- Lauren C Radlinski
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jason Brunton
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Shaun Steele
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, USA
| | - Sharon Taft-Benz
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Thomas H Kawula
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington, USA
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