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Martini AM, Alexander SA, Khare A. Mutations in the Staphylococcus aureus Global Regulator CodY Confer Tolerance to an Interspecies Redox-Active Antimicrobial. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.02.601769. [PMID: 39040146 PMCID: PMC11261909 DOI: 10.1101/2024.07.02.601769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Bacteria often exist in multispecies communities where interactions among different species can modify individual fitness and behavior. Although many competitive interactions have been characterized, molecular adaptations that can counter this antagonism and preserve or increase fitness remain underexplored. Here, we characterize the adaptation of Staphylococcus aureus to pyocyanin, a redox-active interspecies antimicrobial produced by Pseudomonas aeruginosa, a co-infecting pathogen frequently isolated from wound and chronic lung infections with S. aureus. Using experimental evolution, we identified mutations in a conserved global transcriptional regulator, CodY, that confer tolerance to pyocyanin and thereby enhance survival of S. aureus. The transcriptional response of a pyocyanin tolerant CodY mutant to pyocyanin indicated a two-pronged defensive response compared to the wild type. Firstly, the CodY mutant strongly suppressed metabolism, by downregulating pathways associated with core metabolism, especially translation-associated genes, upon exposure to pyocyanin. Metabolic suppression via ATP depletion was sufficient to provide comparable protection against pyocyanin to the wild-type strain. Secondly, while both the wild-type and CodY mutant strains upregulated oxidative stress response pathways, the CodY mutant overexpressed multiple stress response genes compared to the wild type. We determined that catalase overexpression was critical to pyocyanin tolerance as its absence eliminated tolerance in the CodY mutant and overexpression of catalase was sufficient to impart tolerance to the wild-type strain. Together, these results suggest that both transcriptional responses likely contribute to pyocyanin tolerance in the CodY mutant. Our data thus provide new mechanistic insight into adaptation toward interbacterial antagonism via altered regulation that facilitates multifaceted protective cellular responses.
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Affiliation(s)
- Anthony M. Martini
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sara A. Alexander
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Anupama Khare
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Bényei ÉB, Nazeer RR, Askenasy I, Mancini L, Ho PM, Sivarajan GAC, Swain JEV, Welch M. The past, present and future of polymicrobial infection research: Modelling, eavesdropping, terraforming and other stories. Adv Microb Physiol 2024; 85:259-323. [PMID: 39059822 DOI: 10.1016/bs.ampbs.2024.04.002] [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] [Indexed: 07/28/2024]
Abstract
Over the last two centuries, great advances have been made in microbiology as a discipline. Much of this progress has come about as a consequence of studying the growth and physiology of individual microbial species in well-defined laboratory media; so-called "axenic growth". However, in the real world, microbes rarely live in such "splendid isolation" (to paraphrase Foster) and more often-than-not, share the niche with a plethora of co-habitants. The resulting interactions between species (and even between kingdoms) are only very poorly understood, both on a theoretical and experimental level. Nevertheless, the last few years have seen significant progress, and in this review, we assess the importance of polymicrobial infections, and show how improved experimental traction is advancing our understanding of these. A particular focus is on developments that are allowing us to capture the key features of polymicrobial infection scenarios, especially as those associated with the human airways (both healthy and diseased).
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Affiliation(s)
| | | | - Isabel Askenasy
- Department of Biochemistry, Tennis Court Road, Cambridge, United Kingdom
| | - Leonardo Mancini
- Department of Biochemistry, Tennis Court Road, Cambridge, United Kingdom
| | - Pok-Man Ho
- Department of Biochemistry, Tennis Court Road, Cambridge, United Kingdom
| | | | - Jemima E V Swain
- Department of Biochemistry, Tennis Court Road, Cambridge, United Kingdom
| | - Martin Welch
- Department of Biochemistry, Tennis Court Road, Cambridge, United Kingdom.
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3
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Hu KKY, Suri A, Dumsday G, Haritos VS. Cross-feeding promotes heterogeneity within yeast cell populations. Nat Commun 2024; 15:418. [PMID: 38200012 PMCID: PMC10781747 DOI: 10.1038/s41467-023-44623-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
Cellular heterogeneity in cell populations of isogenic origin is driven by intrinsic factors such as stochastic gene expression, as well as external factors like nutrient availability and interactions with neighbouring cells. Heterogeneity promotes population fitness and thus has important implications in antimicrobial and anticancer treatments, where stress tolerance plays a significant role. Here, we study plasmid retention dynamics within a population of plasmid-complemented ura3∆0 yeast cells, and show that the exchange of complementary metabolites between plasmid-carrying prototrophs and plasmid-free auxotrophs allows the latter to survive and proliferate in selective environments. This process also affects plasmid copy number in plasmid-carrying prototrophs, further promoting cellular functional heterogeneity. Finally, we show that targeted genetic engineering can be used to suppress cross-feeding and reduce the frequency of plasmid-free auxotrophs, or to exploit it for intentional population diversification and division of labour in co-culture systems.
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Affiliation(s)
- Kevin K Y Hu
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Ankita Suri
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Geoff Dumsday
- Commonwealth Scientific and Industrial Research Organisation, Clayton, VIC, 3169, Australia
| | - Victoria S Haritos
- Department of Chemical and Biological Engineering, Monash University, Clayton, VIC, 3800, Australia.
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Liu JY, Jia JJ, Liu M, Duan H, Hu ML, Liu C, Xue RY, Jin ZL, Zhang SS, Li GC, Feng R, Jin Z, Li HB, He L. A novel indolylbenzoquinone compound HL-J6 suppresses biofilm formation and α-toxin secretion in methicillin-resistant Staphylococcus aureus. Int J Antimicrob Agents 2023; 62:106972. [PMID: 37741585 DOI: 10.1016/j.ijantimicag.2023.106972] [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: 02/01/2023] [Revised: 08/24/2023] [Accepted: 09/15/2023] [Indexed: 09/25/2023]
Abstract
Eradication of methicillin-resistant Staphylococcus aureus (MRSA) is challenging due to multi-drug resistance of strains and biofilm formation, the latter of which is an important barrier to the penetration of antibiotics and host defences. As such, there is an urgent need to discover and develop novel agents to fight MRSA-associated infection. In this study, HL-J6, a novel indolylbenzoquinone compound, was shown to inhibit S. aureus strains, with a minimum inhibitory concentration against MRSA252 of 2 µg/mL. Moreover, HL-J6 exhibited potent antibiofilm activity in vitro and was able to kill bacteria in biofilm. In the mouse models of wound infection, HL-J6 treatment reduced the MRSA load significantly and inhibited biofilm formation on the wounds. The potent targets of its antibiofilm activity were explored by real-time reverse transcriptase polymerase chain rection, which indicated that HL-J6 downregulated the transcription levels of sarA, atlAE and icaADBC. Moreover, Western blot results showed that HL-J6 reduced the secretion level of α-toxin, a major virulence factor. These findings indicate that HL-J6 is a promising lead compound for the development of novel drugs against MRSA biofilm infections.
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Affiliation(s)
- Jing-Yi Liu
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Jing-Jing Jia
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drugs and Sichuan Research Centre for Drug Precision Industrial Technology, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China
| | - Ming Liu
- Department of Pharmaceutical Analysis, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hao Duan
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China; School of Clinical Medicine, Jiamusi University, Jiamusi, Heilongjiang, China
| | - Ming-Li Hu
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drugs and Sichuan Research Centre for Drug Precision Industrial Technology, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China
| | - Chang Liu
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Ruo-Yi Xue
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Zi-Li Jin
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Shan-Shan Zhang
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China; School of Clinical Medicine, Jiamusi University, Jiamusi, Heilongjiang, China
| | - Guo-Cheng Li
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Rang Feng
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Zhe Jin
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hai-Bo Li
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China.
| | - Ling He
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drugs and Sichuan Research Centre for Drug Precision Industrial Technology, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China.
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The Urinary Microbiome; Axis Crosstalk and Short-Chain Fatty Acid. Diagnostics (Basel) 2022; 12:diagnostics12123119. [PMID: 36553126 PMCID: PMC9777402 DOI: 10.3390/diagnostics12123119] [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: 10/12/2022] [Revised: 11/14/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022] Open
Abstract
Our knowledge that "urine is sterile" is no longer accepted after the development of a next-generation sequencing (NGS) test. Using NGS, microbiota in the human body were discovered, and it is expected that this will improve our understanding of human diseases. However, the mechanism involved in the effect of the microbiome on diseases is still poorly understood. Associations of gut microbiome with diseases have been recently reported. Based on such associations, bladder-gut-brain axis, gut-bladder axis, gut-vagina-bladder axis, and gut-kidney axis as novel mechanisms of action of the microbiome have been suggested. Each axis can influence the development and progression of disease through interactions. In these interactions, metabolites of the microbiome including short-chain fatty acids (SCFA) and the inflammasome play an important role. Inflammasomes are multiprotein oligomers that can initiate inflammatory responses. Inflammasomes can trigger inflammation and pyroptosis and ultimately contribute to disease development. SCFAs play an important role in immune cell migration, cytokine production, and maintenance of cellular homeostasis. Associations of inflammasomes with systemic diseases such as obesity and insulin resistance have been reported. The roles of inflammasomes and SCFAs in kidney, bladder, and prostate diseases have also been revealed recently.
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Islam S, Callender AC, Ho QN, Wakeman CA. Iron restriction induces the small-colony variant phenotype in Staphylococcus aureus. Front Microbiol 2022; 13:978859. [PMID: 36569073 PMCID: PMC9772265 DOI: 10.3389/fmicb.2022.978859] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 11/21/2022] [Indexed: 12/13/2022] Open
Abstract
Pathogens such as Staphylococcus aureus must overcome host-induced selective pressures, including limited iron availability. To cope with the harsh conditions of the host environment, S. aureus can adapt its physiology in multiple ways. One of these adaptations is the fermenting small-colony variant (SCV) phenotype, which is known to be inherently tolerant to certain classes of antibiotics and heme toxicity. We hypothesized that SCVs might also behave uniquely in response to iron starvation since one of the major cellular uses of iron is the respiration machinery. In this study, a respiring strain of S. aureus and fermenting SCV strains were treated with different concentrations of the iron chelator, 2,2' dipyridyl (DIP). Our data demonstrate that a major impact of iron starvation in S. aureus is the repression of respiration and the induction of the SCV phenotype. We demonstrate that the SCV phenotype transiently induced by iron starvation mimics the aminoglycoside recalcitrance exhibited by genetic SCVs. Furthermore, prolonged growth in iron starvation promotes increased emergence of stable aminoglycoside-resistant SCVs relative to the naturally occurring subpopulation of SCVs within an S. aureus community. These findings may have relevance to physiological and evolutionary processes occurring within bacterial populations infecting iron-limited host environments.
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Affiliation(s)
| | | | | | - Catherine A. Wakeman
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, United States
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7
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Lopez JG, Wingreen NS. Noisy metabolism can promote microbial cross-feeding. eLife 2022; 11:70694. [PMID: 35380535 PMCID: PMC8983042 DOI: 10.7554/elife.70694] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 02/21/2022] [Indexed: 12/21/2022] Open
Abstract
Cross-feeding, the exchange of nutrients between organisms, is ubiquitous in microbial communities. Despite its importance in natural and engineered microbial systems, our understanding of how inter-species cross-feeding arises is incomplete, with existing theories limited to specific scenarios. Here, we introduce a novel theory for the emergence of such cross-feeding, which we term noise-averaging cooperation (NAC). NAC is based on the idea that, due to their small size, bacteria are prone to noisy regulation of metabolism which limits their growth rate. To compensate, related bacteria can share metabolites with each other to ‘average out’ noise and improve their collective growth. According to the Black Queen Hypothesis, this metabolite sharing among kin, a form of ‘leakage’, then allows for the evolution of metabolic interdependencies among species including de novo speciation via gene deletions. We first characterize NAC in a simple ecological model of cell metabolism, showing that metabolite leakage can in principle substantially increase growth rate in a community context. Next, we develop a generalized framework for estimating the potential benefits of NAC among real bacteria. Using single-cell protein abundance data, we predict that bacteria suffer from substantial noise-driven growth inefficiencies, and may therefore benefit from NAC. We then discuss potential evolutionary pathways for the emergence of NAC. Finally, we review existing evidence for NAC and outline potential experimental approaches to detect NAC in microbial communities.
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Affiliation(s)
- Jaime G Lopez
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, United States
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8
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Quinones: More Than Electron Shuttles. Res Microbiol 2022; 173:103953. [DOI: 10.1016/j.resmic.2022.103953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/08/2022] [Accepted: 04/14/2022] [Indexed: 11/21/2022]
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9
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Mixed Populations and Co-Infection: Pseudomonas aeruginosa and Staphylococcus aureus. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:397-424. [DOI: 10.1007/978-3-031-08491-1_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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10
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Daisley BA, Koenig D, Engelbrecht K, Doney L, Hards K, Al KF, Reid G, Burton JP. Emerging connections between gut microbiome bioenergetics and chronic metabolic diseases. Cell Rep 2021; 37:110087. [PMID: 34879270 DOI: 10.1016/j.celrep.2021.110087] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/03/2021] [Accepted: 11/10/2021] [Indexed: 12/25/2022] Open
Abstract
The conventional viewpoint of single-celled microbial metabolism fails to adequately depict energy flow at the systems level in host-adapted microbial communities. Emerging paradigms instead support that distinct microbiomes develop interconnected and interdependent electron transport chains that rely on cooperative production and sharing of bioenergetic machinery (i.e., directly involved in generating ATP) in the extracellular space. These communal resources represent an important subset of the microbial metabolome, designated here as the "pantryome" (i.e., pantry or external storage compartment), that critically supports microbiome function and can exert multifunctional effects on host physiology. We review these interactions as they relate to human health by detailing the genomic-based sharing potential of gut-derived bacterial and archaeal reference strains. Aromatic amino acids, metabolic cofactors (B vitamins), menaquinones (vitamin K2), hemes, and short-chain fatty acids (with specific emphasis on acetate as a central regulator of symbiosis) are discussed in depth regarding their role in microbiome-related metabolic diseases.
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Affiliation(s)
- Brendan A Daisley
- Department of Microbiology & Immunology, The University of Western Ontario, London, ON N6A 5C1, Canada; Canadian Centre for Human Microbiome and Probiotics Research, London, ON N6A 4V2, Canada
| | - David Koenig
- Kimberly Clark Corporation, Global Research and Engineering-Life Science, Neenah, WI, USA
| | - Kathleen Engelbrecht
- Kimberly Clark Corporation, Global Research and Engineering-Life Science, Neenah, WI, USA
| | - Liz Doney
- Kimberly Clark Corporation, Global Research and Engineering-Life Science, Neenah, WI, USA
| | - Kiel Hards
- Department of Microbiology and Immunology, University of Otago, Dunedin, Otago, New Zealand
| | - Kait F Al
- Department of Microbiology & Immunology, The University of Western Ontario, London, ON N6A 5C1, Canada; Canadian Centre for Human Microbiome and Probiotics Research, London, ON N6A 4V2, Canada
| | - Gregor Reid
- Department of Microbiology & Immunology, The University of Western Ontario, London, ON N6A 5C1, Canada; Canadian Centre for Human Microbiome and Probiotics Research, London, ON N6A 4V2, Canada; Department of Surgery, Division of Urology, Schulich School of Medicine, London, ON N6A 5C1, Canada
| | - Jeremy P Burton
- Department of Microbiology & Immunology, The University of Western Ontario, London, ON N6A 5C1, Canada; Canadian Centre for Human Microbiome and Probiotics Research, London, ON N6A 4V2, Canada; Department of Surgery, Division of Urology, Schulich School of Medicine, London, ON N6A 5C1, Canada.
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11
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Heme-Dependent Siderophore Utilization Promotes Iron-Restricted Growth of the Staphylococcus aureus hemB Small-Colony Variant. J Bacteriol 2021; 203:e0045821. [PMID: 34606375 DOI: 10.1128/jb.00458-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Respiration-deficient Staphylococcus aureus small-colony variants (SCVs) frequently cause persistent infections, which necessitates they acquire iron, yet how SCVs obtain iron remains unknown. To address this, we created a stable hemB mutant from S. aureus USA300 strain LAC. The hemB SCV utilized exogenously supplied hemin but was attenuated for growth under conditions of iron starvation. Transcriptome sequencing (RNA-seq) showed that both wild-type (WT) S. aureus and the hemB mutant sense and respond to iron starvation; however, growth assays show that the hemB mutant is defective for siderophore-mediated iron acquisition. Indeed, the hemB SCV demonstrated limited utilization of endogenous staphyloferrin B or exogenously provided staphyloferrin A, deferoxamine mesylate (Desferal), and epinephrine. Direct measurement of intracellular ATP in hemB and WT S. aureus revealed that both strains can generate comparable levels of ATP during exponential growth, suggesting defects in ATP production cannot account for the inability to efficiently utilize siderophores. Defective siderophore utilization by hemB bacteria was also evident in vivo, as administration of Desferal failed to promote hemB bacterial growth in every organ analyzed except for the kidneys. In support of the hypothesis that S. aureus accesses heme in kidney abscesses, in vitro analyses revealed that increased hemin availability enables hemB bacteria to utilize siderophores for growth when iron availability is restricted. Taken together, our data support the conclusion that hemin is used not only as an iron source itself but also as a nutrient that promotes utilization of siderophore-iron complexes. IMPORTANCE S. aureus small-colony variants (SCVs) are associated with chronic recurrent infection and worsened clinical outcome. SCVs persist within the host despite administration of antibiotics. This study yields insight into how S. aureus SCVs acquire iron, which during infection of a host is a difficult-to-acquire metal nutrient. Under hemin-limited conditions, hemB S. aureus is impaired for siderophore-dependent growth, and in agreement, murine infection indicates that hemin-deficient SCVs meet their nutritional requirement for iron through utilization of hemin. Importantly, we demonstrate that hemB SCVs rely upon hemin as a nutrient to promote siderophore utilization. Therefore, perturbation of heme biosynthesis and/or utilization represents a viable to strategy to mitigate the ability of SCV bacteria to acquire siderophore-bound iron during infection.
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Herrin BE, Islam S, Rentschler KN, Pert LH, Kopanski SP, Wakeman CA. Haem toxicity provides a competitive advantage to the clinically relevant Staphylococcus aureus small colony variant phenotype. MICROBIOLOGY (READING, ENGLAND) 2021; 167:001044. [PMID: 33749578 PMCID: PMC8289220 DOI: 10.1099/mic.0.001044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Microorganisms encounter toxicities inside the host. Many pathogens exist as subpopulations to maximize survivability. Subpopulations of Staphylococcus aureus include antibiotic-tolerant small colony variants (SCVs). These mutants often emerge following antibiotic treatment but can be present in infections prior to antibiotic exposure. We hypothesize that haem toxicity in the host selects for respiration-deficient S. aureus SCVs in the absence of antibiotics. We demonstrate that some but not all respiration-deficient SCV phenotypes are more protective than the haem detoxification system against transient haem exposure, indicating that haem toxicity in the host may contribute to the dominance of menaquinone-deficient and haem-deficient SCVs prior to antibiotic treatment.
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Affiliation(s)
- Brittany E. Herrin
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
- Present address: Department of Biology, Indiana University, Bloomington, IN, USA
| | - Shariful Islam
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | | | - Lauren H. Pert
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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Interspecies Metabolic Complementation in Cystic Fibrosis Pathogens via Purine Exchange. Pathogens 2021; 10:pathogens10020146. [PMID: 33535659 PMCID: PMC7912780 DOI: 10.3390/pathogens10020146] [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: 12/22/2020] [Revised: 01/28/2021] [Accepted: 01/29/2021] [Indexed: 11/17/2022] Open
Abstract
Cystic fibrosis (CF) is a genetic disease frequently associated with chronic lung infections caused by a consortium of pathogens. It is common for auxotrophy (the inability to biosynthesize certain essential metabolites) to develop in clinical isolates of the dominant CF pathogen Pseudomonas aeruginosa, indicating that the CF lung environment is replete in various nutrients. Many of these nutrients are likely to come from the host tissues, but some may come from the surrounding polymicrobial community within the lungs of CF patients as well. To assess the feasibility of nutrient exchange within the polymicrobial community of the CF lung, we selected P. aeruginosa and Staphylococcus aureus, two of the most prevalent species found in the CF lung environment. By comparing the polymicrobial culture of wild-type strains relative to their purine auxotrophic counterparts, we were able to observe metabolic complementation occurring in both P. aeruginosa and S. aureus when grown with a purine-producing cross-species pair. While our data indicate that some of this complementation is likely derived from extracellular DNA freed by lysis of S. aureus by the highly competitive P. aeruginosa, the partial complementation of S. aureus purine deficiency by P. aeruginosa demonstrates that bidirectional nutrient exchange between these classic competitors is possible.
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14
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Extracellular Metabolism Sets the Table for Microbial Cross-Feeding. Microbiol Mol Biol Rev 2021; 85:85/1/e00135-20. [PMID: 33441489 DOI: 10.1128/mmbr.00135-20] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The transfer of nutrients between cells, or cross-feeding, is a ubiquitous feature of microbial communities with emergent properties that influence our health and orchestrate global biogeochemical cycles. Cross-feeding inevitably involves the externalization of molecules. Some of these molecules directly serve as cross-fed nutrients, while others can facilitate cross-feeding. Altogether, externalized molecules that promote cross-feeding are diverse in structure, ranging from small molecules to macromolecules. The functions of these molecules are equally diverse, encompassing waste products, enzymes, toxins, signaling molecules, biofilm components, and nutrients of high value to most microbes, including the producer cell. As diverse as the externalized and transferred molecules are the cross-feeding relationships that can be derived from them. Many cross-feeding relationships can be summarized as cooperative but are also subject to exploitation. Even those relationships that appear to be cooperative exhibit some level of competition between partners. In this review, we summarize the major types of actively secreted, passively excreted, and directly transferred molecules that either form the basis of cross-feeding relationships or facilitate them. Drawing on examples from both natural and synthetic communities, we explore how the interplay between microbial physiology, environmental parameters, and the diverse functional attributes of extracellular molecules can influence cross-feeding dynamics. Though microbial cross-feeding interactions represent a burgeoning field of interest, we may have only begun to scratch the surface.
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15
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Chatterjee A, Willett JLE, Dunny GM, Duerkop BA. Phage infection and sub-lethal antibiotic exposure mediate Enterococcus faecalis type VII secretion system dependent inhibition of bystander bacteria. PLoS Genet 2021; 17:e1009204. [PMID: 33411815 PMCID: PMC7790226 DOI: 10.1371/journal.pgen.1009204] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/08/2020] [Indexed: 02/07/2023] Open
Abstract
Bacteriophages (phages) are being considered as alternative therapeutics for the treatment of multidrug resistant bacterial infections. Considering phages have narrow host-ranges, it is generally accepted that therapeutic phages will have a marginal impact on non-target bacteria. We have discovered that lytic phage infection induces transcription of type VIIb secretion system (T7SS) genes in the pathobiont Enterococcus faecalis. Membrane damage during phage infection induces T7SS gene expression resulting in cell contact dependent antagonism of different Gram positive bystander bacteria. Deletion of essB, a T7SS structural component, abrogates phage-mediated killing of bystanders. A predicted immunity gene confers protection against T7SS mediated inhibition, and disruption of its upstream LXG toxin gene rescues growth of E. faecalis and Staphylococcus aureus bystanders. Phage induction of T7SS gene expression and bystander inhibition requires IreK, a serine/threonine kinase, and OG1RF_11099, a predicted GntR-family transcription factor. Additionally, sub-lethal doses of membrane targeting and DNA damaging antibiotics activated T7SS expression independent of phage infection, triggering T7SS antibacterial activity against bystander bacteria. Our findings highlight how phage infection and antibiotic exposure of a target bacterium can affect non-target bystander bacteria and implies that therapies beyond antibiotics, such as phage therapy, could impose collateral damage to polymicrobial communities. Renewed interest in phages as alternative therapeutics to combat multi-drug resistant bacterial infections, highlights the importance of understanding the consequences of phage-bacteria interactions in the context of microbial communities. Although it is well established that phages are highly specific for their host bacterium, there is no clear consensus on whether or not phage infection (and thus phage therapy) would impose collateral damage to non-target bacteria in polymicrobial communities. Here we provide direct evidence of how phage infection of a clinically relevant pathogen triggers an intrinsic type VII secretion system (T7SS) antibacterial response that consequently restricts the growth of neighboring bacterial cells that are not susceptible to phage infection. Phage induction of T7SS activity is a stress response and in addition to phages, T7SS antagonism can be induced using sub-inhibitory concentrations of antibiotics that facilitate membrane or DNA damage. Together these data show that a bacterial pathogen responds to diverse stressors to induce T7SS activity which manifests through the antagonism of neighboring non-kin bystander bacterial cells.
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Affiliation(s)
- Anushila Chatterjee
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States of America
| | - Julia L. E. Willett
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States of America
| | - Gary M. Dunny
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States of America
| | - Breck A. Duerkop
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States of America
- * E-mail:
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Snell SB, Gill AL, Haidaris CG, Foster TH, Baran TM, Gill SR. Staphylococcus aureus Tolerance and Genomic Response to Photodynamic Inactivation. mSphere 2021; 6:e00762-20. [PMID: 33408223 PMCID: PMC7845598 DOI: 10.1128/msphere.00762-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 12/08/2020] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen with a clinical spectrum ranging from asymptomatic skin colonization to invasive infections. While traditional antibiotic therapies can be effective against S. aureus, the increasing prevalence of antibiotic-resistant strains results in treatment failures and high mortality rates. Photodynamic inactivation (PDI) is an innovative and promising alternative to antibiotics. While progress has been made in our understanding of the bacterial response to PDI, major gaps remain in our knowledge of PDI tolerance, the global cellular response, and adaptive genomic mutations acquired as a result of PDI. To address these gaps, S. aureus HG003 and isogenic mutants with mutations in agr, mutS, mutL, and mutY exposed to single or multiple doses of PDI were assessed for survival and tolerance and examined by global transcriptome and genome analyses to identify regulatory and genetic adaptations that contribute to tolerance. Pathways in inorganic ion transport, oxidative response, DNA replication recombination and repair, and cell wall and membrane biogenesis were identified in a global cellular response to PDI. Tolerance to PDI was associated with superoxide dismutase and the S. aureus global methylhydroquinone (MHQ)-quinone transcriptome network. Genome analysis of PDI-tolerant HG003 identified a nonsynonymous mutation in the quinone binding domain of the transcriptional repressor QsrR, which mediates quinone sensing and oxidant response. Acquisition of a heritable QsrR mutation through repeated PDI treatment demonstrates selective adaption of S. aureus to PDI. PDI tolerance of a qsrR gene deletion in HG003 confirmed that QsrR regulates the S. aureus response to PDI.IMPORTANCEStaphylococcus aureus can cause disease at most body sites, with illness ranging from asymptomatic infection to death. The increasing prevalence of antibiotic-resistant strains results in treatment failures and high mortality rates. S. aureus acquires resistance to antibiotics through multiple mechanisms, often by genetic variation that alters antimicrobial targets. Photodynamic inactivation (PDI), which employs a combination of a nontoxic dye and low-intensity visible light, is a promising alternative to antibiotics that effectively eradicates S. aureus in human infections when antibiotics are no longer effective. In this study, we demonstrate that repeated exposure to PDI results in resistance of S. aureus to further PDI treatment and identify the underlying bacterial mechanisms that contribute to resistance. This work supports further analysis of these mechanisms and refinement of this novel technology as an adjunctive treatment for S. aureus infections.
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Affiliation(s)
- Sara B Snell
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
| | - Ann Lindley Gill
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
| | - Constantine G Haidaris
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
- Center for Oral Biology, University of Rochester Medical Center, Rochester, New York, USA
| | - Thomas H Foster
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Timothy M Baran
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Steven R Gill
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA
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Host nutrient milieu drives an essential role for aspartate biosynthesis during invasive Staphylococcus aureus infection. Proc Natl Acad Sci U S A 2020; 117:12394-12401. [PMID: 32414924 PMCID: PMC7275739 DOI: 10.1073/pnas.1922211117] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus can infect a diverse array of host environments. The broad tissue tropism of S. aureus requires metabolic flexibility to utilize the variety of nutrient sources found within target organ systems. In this work, we conducted a systematic analysis of the central metabolic pathways required for S. aureus survival during bone infection, one of the most frequent sites of invasive staphylococcal disease. We show that S. aureus requires aspartate biosynthesis to survive during bone infection, despite possessing an aspartate transporter, due to inhibition of aspartate utilization by the amino acid glutamate. Our results reveal a crucial role for inflammation-associated shifts in the host nutrient milieu for determining the metabolic pathways utilized by S. aureus during invasive infection. The bacterial pathogen Staphylococcus aureus is capable of infecting a broad spectrum of host tissues, in part due to flexibility of metabolic programs. S. aureus, like all organisms, requires essential biosynthetic intermediates to synthesize macromolecules. We therefore sought to determine the metabolic pathways contributing to synthesis of essential precursors during invasive S. aureus infection. We focused specifically on staphylococcal infection of bone, one of the most common sites of invasive S. aureus infection and a unique environment characterized by dynamic substrate accessibility, infection-induced hypoxia, and a metabolic profile skewed toward aerobic glycolysis. Using a murine model of osteomyelitis, we examined survival of S. aureus mutants deficient in central metabolic pathways, including glycolysis, gluconeogenesis, the tricarboxylic acid (TCA) cycle, and amino acid synthesis/catabolism. Despite the high glycolytic demand of skeletal cells, we discovered that S. aureus requires glycolysis for survival in bone. Furthermore, the TCA cycle is dispensable for survival during osteomyelitis, and S. aureus instead has a critical need for anaplerosis. Bacterial synthesis of aspartate in particular is absolutely essential for staphylococcal survival in bone, despite the presence of an aspartate transporter, which we identified as GltT and confirmed biochemically. This dependence on endogenous aspartate synthesis derives from the presence of excess glutamate in infected tissue, which inhibits aspartate acquisition by S. aureus. Together, these data elucidate the metabolic pathways required for staphylococcal infection within bone and demonstrate that the host nutrient milieu can determine essentiality of bacterial nutrient biosynthesis pathways despite the presence of dedicated transporters.
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McCarville JL, Chen GY, Cuevas VD, Troha K, Ayres JS. Microbiota Metabolites in Health and Disease. Annu Rev Immunol 2020; 38:147-170. [DOI: 10.1146/annurev-immunol-071219-125715] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabolism is one of the strongest drivers of interkingdom interactions—including those between microorganisms and their multicellular hosts. Traditionally thought to fuel energy requirements and provide building blocks for biosynthetic pathways, metabolism is now appreciated for its role in providing metabolites, small-molecule intermediates generated from metabolic processes, to perform various regulatory functions to mediate symbiotic relationships between microbes and their hosts. Here, we review recent advances in our mechanistic understanding of how microbiota-derived metabolites orchestrate and support physiological responses in the host, including immunity, inflammation, defense against infections, and metabolism. Understanding how microbes metabolically communicate with their hosts will provide us an opportunity to better describe how a host interacts with all microbes—beneficial, pathogenic, and commensal—and an opportunity to discover new ways to treat microbial-driven diseases.
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Affiliation(s)
- Justin L. McCarville
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Grischa Y. Chen
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Víctor D. Cuevas
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Katia Troha
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Janelle S. Ayres
- Molecular and Systems Physiology Laboratory, Gene Expression Laboratory, NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, California 92037, USA
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Ibberson CB, Whiteley M. The social life of microbes in chronic infection. Curr Opin Microbiol 2020; 53:44-50. [PMID: 32145635 DOI: 10.1016/j.mib.2020.02.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 01/24/2020] [Accepted: 02/02/2020] [Indexed: 01/21/2023]
Abstract
Chronic infections place a significant burden on healthcare systems, requiring over $25 billion in treatment annually in the United States alone [1,2]. Notably, the majority of chronic infections, which include cystic fibrosis (CF), chronic wounds, otitis media, periodontitis, urinary tract infections, and osteomyelitis, are considered polymicrobial and are often recalcitrant to antibiotic treatment [1-9]. Although we know that diverse communities of microbes comprise these infections, how microbes interact and the impacts of these interactions on human disease are less understood. Here, we discuss recent advances in our understanding of how bacteria communicate in chronic infection, with a focus on Staphylococcus aureus and Pseudomonas aeruginosa, and we highlight outstanding questions and controversies in the field.
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Affiliation(s)
- Carolyn B Ibberson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States; Emory-Children's Cystic Fibrosis Center, Atlanta, GA 30332, United States; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30332, United States.
| | - Marvin Whiteley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States; Emory-Children's Cystic Fibrosis Center, Atlanta, GA 30332, United States; Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30332, United States
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20
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Salmonella enterica Requires Lipid Metabolism Genes To Replicate in Proinflammatory Macrophages and Mice. Infect Immun 2019; 88:IAI.00776-19. [PMID: 31611277 DOI: 10.1128/iai.00776-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 10/06/2019] [Indexed: 12/28/2022] Open
Abstract
To survive and replicate during infection, pathogens utilize different carbon and energy sources depending on the nutritional landscape of their host microenvironment. Salmonella enterica serovar Typhimurium is an intracellular bacterial pathogen that occupies diverse cellular niches. While it is clear that Salmonella Typhimurium requires access to glucose during systemic infection, data on the need for lipid metabolism are mixed. We report that Salmonella Typhimurium strains lacking lipid metabolism genes were defective for systemic infection of mice. Bacterial lipid import, β-oxidation, and glyoxylate shunt genes were required for tissue colonization upon oral or intraperitoneal inoculation. In cultured macrophages, lipid import and β-oxidation genes were required for bacterial replication and/or survival only when the cell culture medium was supplemented with nonessential amino acids. Removal of glucose from tissue culture medium further enhanced these phenotypes and, in addition, conferred a requirement for glyoxylate shunt genes. We also observed that Salmonella Typhimurium needs lipid metabolism genes in proinflammatory but not anti-inflammatory macrophages. These results suggest that during systemic infection, the Salmonella Typhimurium that relies upon host lipids to replicate is within proinflammatory macrophages that have access to amino acids but not glucose. An improved understanding of the host microenvironments in which pathogens have specific metabolic requirements may facilitate the development of targeted approaches to treatment.
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21
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Jenkins CL, Bean HD. Influence of media on the differentiation of Staphylococcus spp. by volatile compounds. J Breath Res 2019; 14:016007. [PMID: 31461416 DOI: 10.1088/1752-7163/ab3e9d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Staphylococcus aureus asymptomatically colonizes a third of the world's population, and it is an opportunistic pathogen that can cause life threatening diseases. To diagnose S. aureus infections, it is necessary to differentiate S. aureus from the ubiquitous human commensal Staphylococcus epidermidis, which beneficially colonizes the skin of all humans. Efforts are underway to identify volatile biomarkers for diagnosing S. aureus infections, but to date no studies have investigated whether S. aureus and S. epidermidis can be reliably differentiated under a variety of growth conditions. The overall goal of this study was to evaluate the influence of growth medium on the ability to differentiate S. aureus and S. epidermidis based on their volatile profiles. We used headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) to examine the headspace volatiles of S. aureus and S. epidermidis when aerobically grown in four different complex media. We detected 337 volatile features when culturing S. aureus and S. epidermidis in four complex media, termed the staph volatiles, and found only 20%-40% concurrence in the volatiles produced by these two species in any single medium. Using principal components analysis and hierarchical clustering analysis on the staph volatiles, we observed that S. aureus and S. epidermidis clustered independently from each other, and distinctly clustered by growth medium within species. Removing volatiles that are species and/or media-specific from the analysis reduced the resolution between species clusters, but in all models clustering by species overrode clustering by media type. These analyses suggest that, while volatile profiles are media-specific, species differences dominate the staph volatilome. These data enable future investigations into the identification of volatile biomarkers to discriminate staphylococcal pathogens versus commensals, which will improve staph diagnoses and provide insights into the biochemistry of staph infections and immunity.
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Affiliation(s)
- Carrie L Jenkins
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States of America. Center for Fundamental and Applied Microbiomics, The Biodesign Institute, Tempe, AZ 85287, United States of America
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22
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Ribeiro da Cunha B, Fonseca LP, Calado CRC. A phenotypic screening bioassay for Escherichia coli stress and antibiotic responses based on Fourier-transform infrared (FTIR) spectroscopy and multivariate analysis. J Appl Microbiol 2019; 127:1776-1789. [PMID: 31464358 DOI: 10.1111/jam.14429] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 08/21/2019] [Accepted: 08/21/2019] [Indexed: 12/22/2022]
Abstract
AIMS To develop and optimize a Fourier-transform infrared spectroscopy (FTIRS) phenotypic screening bioassay for stress responses, regarding the effect of nutrient content, bacterial growth phase and stress agent exposure time. METHODS AND RESULTS A high-throughput FTIRS bioassay was developed to distinguish the stress responses of Escherichia coli to sodium hydroxide, hydrochloric acid, sodium chloride, sodium hypochlorite and ethanol. Principal component analysis and hierarchical clustering were used to quantify the effect of each parameter on bioassay performance, namely its reproducibility and metabolic resolution. Bioassay performance varied greatly, ranging from poor to very good. Spectra were partitioned into biologically relevant regions to evaluate their contributions to bioassay performance, but further improvements were not observed. Bioassay optimization was validated against empirical parameters, which confirmed a closer representation of known mechanisms on the antibiotic-induced stress responses. CONCLUSIONS The optimized bioassay used standard nutrient content, cells in the late-stationary growth phase and a one-shift exposure duration. Only the optimized bioassay adequately and reproducibly distinguished the E. coli stress and antibiotic responses. The absence of performance improvements using partitioned spectra indicated that stress responses are imprinted on the whole-spectra metabolic signature. SIGNIFICANCE AND IMPACT OF THE STUDY Highly optimized FTIRS bioassay parameters are vital in capturing whole-spectra metabolic signatures that can be used for satisfactory and reproducible phenotypic screening of stress and antibiotic responses.
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Affiliation(s)
- B Ribeiro da Cunha
- iBB - Institute of Bioengineering and Biosciences (iBB), Instituto Superior Técnico (IST), Universidade de Lisboa, Lisboa, Portugal.,ISEL - Instituto Superior de Engenharia de Lisboa (ISEL), Instituto Politécnico de Lisboa (IPL), Lisboa, Portugal
| | - L P Fonseca
- iBB - Institute of Bioengineering and Biosciences (iBB), Instituto Superior Técnico (IST), Universidade de Lisboa, Lisboa, Portugal
| | - C R C Calado
- ISEL - Instituto Superior de Engenharia de Lisboa (ISEL), Instituto Politécnico de Lisboa (IPL), Lisboa, Portugal
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Selective pressures during chronic infection drive microbial competition and cooperation. NPJ Biofilms Microbiomes 2019; 5:16. [PMID: 31263568 PMCID: PMC6555799 DOI: 10.1038/s41522-019-0089-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/15/2019] [Indexed: 12/14/2022] Open
Abstract
Chronic infections often contain complex mixtures of pathogenic and commensal microorganisms ranging from aerobic and anaerobic bacteria to fungi and viruses. The microbial communities present in infected tissues are not passively co-existing but rather actively interacting with each other via a spectrum of competitive and/or cooperative mechanisms. Competition versus cooperation in these microbial interactions can be driven by both the composition of the microbial community as well as the presence of host defense strategies. These interactions are typically mediated via the production of secreted molecules. In this review, we will explore the possibility that microorganisms competing for nutrients at the host–pathogen interface can evolve seemingly cooperative mechanisms by controlling the production of subsets of secreted virulence factors. We will also address interspecies versus intraspecies utilization of community resources and discuss the impact that this phenomenon might have on co-evolution at the host–pathogen interface.
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24
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Abstract
Staphylococcus aureus is clearly the most pathogenic member of the Staphylococcaceae. This is in large part due to the acquisition of an impressive arsenal of virulence factors that are coordinately regulated by a series of dedicated transcription factors. What is becoming more and more appreciated in the field is the influence of the metabolic state of S. aureus on the activity of these virulence regulators and their roles in modulating metabolic gene expression. Here I highlight recent advances in S. aureus metabolism as it pertains to virulence. Specifically, mechanisms of nutrient acquisition are outlined including carbohydrate and non-carbohydrate carbon/energy sources as well as micronutrient (Fe, Mn, Zn and S) acquisition. Additionally, energy producing strategies (respiration versus fermentation) are discussed and put in the context of pathogenesis. Finally, transcriptional regulators that coordinate metabolic gene expression are outlined, particularly those that affect the activities of major virulence factor regulators. This chapter essentially connects many recent observations that link the metabolism of S. aureus to its overall pathogenesis and hints that the mere presence of a plethora of virulence factors may not entirely explain the extraordinary pathogenic potential of S. aureus.
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25
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Videira MAM, Lobo SAL, Silva LSO, Palmer DJ, Warren MJ, Prieto M, Coutinho A, Sousa FL, Fernandes F, Saraiva LM. Staphylococcus aureushaem biosynthesis and acquisition pathways are linked through haem monooxygenase IsdG. Mol Microbiol 2018; 109:385-400. [DOI: 10.1111/mmi.14060] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Marco A. M. Videira
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Oeiras Portugal
| | - Susana A. L. Lobo
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Oeiras Portugal
- iBET, Instituto de Biologia Experimental e Tecnológica; Oeiras Portugal
| | - Liliana S. O. Silva
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Oeiras Portugal
| | - David J. Palmer
- School of Biosciences; University of Kent, Giles Lane; Canterbury UK
| | - Martin J. Warren
- School of Biosciences; University of Kent, Giles Lane; Canterbury UK
| | - Manuel Prieto
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico; Universidade de Lisboa; Lisboa Portugal
| | - Ana Coutinho
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico; Universidade de Lisboa; Lisboa Portugal
- Departamento de Química e Bioquímica, Faculdade de Ciências; Universidade de Lisboa; Lisboa Portugal
| | - Filipa L. Sousa
- Department of Ecogenomics and Systems Biology; University of Vienna; Vienna Austria
| | - Fábio Fernandes
- Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico; Universidade de Lisboa; Lisboa Portugal
- Research Unit on Applied Molecular Biosciences−Rede de Química e Tecnologia (UCIBIO-REQUIMTE), Departamento de Química, Faculdade de Ciências e Tecnologia; Universidade Nova de Lisboa; Caparica Portugal
| | - Lígia M. Saraiva
- Instituto de Tecnologia Química e Biológica António Xavier; Universidade Nova de Lisboa; Oeiras Portugal
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An Escherichia coli Nitrogen Starvation Response Is Important for Mutualistic Coexistence with Rhodopseudomonas palustris. Appl Environ Microbiol 2018; 84:AEM.00404-18. [PMID: 29728387 DOI: 10.1128/aem.00404-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 04/28/2018] [Indexed: 02/04/2023] Open
Abstract
Microbial mutualistic cross-feeding interactions are ubiquitous and can drive important community functions. Engaging in cross-feeding undoubtedly affects the physiology and metabolism of individual species involved. However, the nature in which an individual species' physiology is influenced by cross-feeding and the importance of those physiological changes for the mutualism have received little attention. We previously developed a genetically tractable coculture to study bacterial mutualisms. The coculture consists of fermentative Escherichia coli and phototrophic Rhodopseudomonas palustris In this coculture, E. coli anaerobically ferments sugars into excreted organic acids as a carbon source for R. palustris In return, a genetically engineered R. palustris strain constitutively converts N2 into NH4+, providing E. coli with essential nitrogen. Using transcriptome sequencing (RNA-seq) and proteomics, we identified transcript and protein levels that differ in each partner when grown in coculture versus monoculture. When in coculture with R. palustris, E. coli gene expression changes resembled a nitrogen starvation response under the control of the transcriptional regulator NtrC. By genetically disrupting E. coli NtrC, we determined that a nitrogen starvation response is important for a stable coexistence, especially at low R. palustris NH4+ excretion levels. Destabilization of the nitrogen starvation regulatory network resulted in variable growth trends and, in some cases, extinction. Our results highlight that alternative physiological states can be important for survival within cooperative cross-feeding relationships.IMPORTANCE Mutualistic cross-feeding between microbes within multispecies communities is widespread. Studying how mutualistic interactions influence the physiology of each species involved is important for understanding how mutualisms function and persist in both natural and applied settings. Using a bacterial mutualism consisting of Rhodopseudomonas palustris and Escherichia coli growing cooperatively through bidirectional nutrient exchange, we determined that an E. coli nitrogen starvation response is important for maintaining a stable coexistence. The lack of an E. coli nitrogen starvation response ultimately destabilized the mutualism and, in some cases, led to community collapse after serial transfers. Our findings thus inform on the potential necessity of an alternative physiological state for mutualistic coexistence with another species compared to the physiology of species grown in isolation.
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Hakansson AP, Orihuela CJ, Bogaert D. Bacterial-Host Interactions: Physiology and Pathophysiology of Respiratory Infection. Physiol Rev 2018; 98:781-811. [PMID: 29488821 PMCID: PMC5966719 DOI: 10.1152/physrev.00040.2016] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 02/06/2023] Open
Abstract
It has long been thought that respiratory infections are the direct result of acquisition of pathogenic viruses or bacteria, followed by their overgrowth, dissemination, and in some instances tissue invasion. In the last decades, it has become apparent that in contrast to this classical view, the majority of microorganisms associated with respiratory infections and inflammation are actually common members of the respiratory ecosystem and only in rare circumstances do they cause disease. This suggests that a complex interplay between host, environment, and properties of colonizing microorganisms together determines disease development and its severity. To understand the pathophysiological processes that underlie respiratory infectious diseases, it is therefore necessary to understand the host-bacterial interactions occurring at mucosal surfaces, along with the microbes inhabiting them, during symbiosis. Current knowledge regarding host-bacterial interactions during asymptomatic colonization will be discussed, including a plausible role for the human microbiome in maintaining a healthy state. With this as a starting point, we will discuss possible disruptive factors contributing to dysbiosis, which is likely to be a key trigger for pathobionts in the development and pathophysiology of respiratory diseases. Finally, from this renewed perspective, we will reflect on current and potential new approaches for treatment in the future.
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Affiliation(s)
- A P Hakansson
- Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University , Lund , Sweden ; Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama ; and Center for Inflammation Research, Queens Medical Research Institute, University of Edinburgh , Edinburgh , United Kingdom
| | - C J Orihuela
- Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University , Lund , Sweden ; Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama ; and Center for Inflammation Research, Queens Medical Research Institute, University of Edinburgh , Edinburgh , United Kingdom
| | - D Bogaert
- Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University , Lund , Sweden ; Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama ; and Center for Inflammation Research, Queens Medical Research Institute, University of Edinburgh , Edinburgh , United Kingdom
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Nontargeted Metabolomics Reveals the Multilevel Response to Antibiotic Perturbations. Cell Rep 2018; 19:1214-1228. [PMID: 28494870 DOI: 10.1016/j.celrep.2017.04.002] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 09/27/2016] [Accepted: 03/31/2017] [Indexed: 11/21/2022] Open
Abstract
Microbes have shown a remarkable ability in evading the killing actions of antimicrobial agents, such that treatment of bacterial infections represents once more an urgent global challenge. Understanding the initial bacterial response to antimicrobials may reveal intrinsic tolerance mechanisms to antibiotics and suggest alternative and less conventional therapeutic strategies. Here, we used mass spectrometry-based metabolomics to monitor the immediate metabolic response of Escherichia coli to a variety of antibiotic perturbations. We show that rapid metabolic changes can reflect drug mechanisms of action and reveal the active role of metabolism in mediating the first stress response to antimicrobials. We uncovered a role for ammonium imbalance in aggravating chloramphenicol toxicity and the essential function of deoxythymidine 5'-diphosphate (dTDP)-rhamnose synthesis for the immediate transcriptional upregulation of GyrA in response to quinolone antibiotics. Our results suggest bacterial metabolism as an attractive target to interfere with the early bacterial response to antibiotic treatments and reduce the probability for survival and eventual evolution of antibiotic resistance.
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Recipient-Biased Competition for an Intracellularly Generated Cross-Fed Nutrient Is Required for Coexistence of Microbial Mutualists. mBio 2017; 8:mBio.01620-17. [PMID: 29184014 PMCID: PMC5705916 DOI: 10.1128/mbio.01620-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Many mutualistic microbial relationships are based on nutrient cross-feeding. Traditionally, cross-feeding is viewed as being unidirectional, from the producer to the recipient. This is likely true when a producer’s waste, such as a fermentation product, has value only for a recipient. However, in some cases the cross-fed nutrient holds value for both the producer and the recipient. In such cases, there is potential for nutrient reacquisition by producer cells in a population, leading to competition against recipients. Here, we investigated the consequences of interpartner competition for cross-fed nutrients on mutualism dynamics by using an anaerobic coculture pairing fermentative Escherichia coli and phototrophic Rhodopseudomonas palustris. In this coculture, E. coli excretes waste organic acids that provide a carbon source for R. palustris. In return, R. palustris cross-feeds E. coli ammonium (NH4+), a compound that both species value. To explore the potential for interpartner competition, we first used a kinetic model to simulate cocultures with varied affinities for NH4+ in each species. The model predicted that interpartner competition for NH4+ could profoundly impact population dynamics. We then experimentally tested the predictions by culturing mutants lacking NH4+ transporters in both NH4+ competition assays and mutualistic cocultures. Both theoretical and experimental results indicated that the recipient must have a competitive advantage in acquiring cross-fed NH4+ to sustain the mutualism. This recipient-biased competitive advantage is predicted to be crucial, particularly when the communally valuable nutrient is generated intracellularly. Thus, the very metabolites that form the basis for mutualistic cross-feeding can also be subject to competition between mutualistic partners. Mutualistic relationships, particularly those based on nutrient cross-feeding, promote stability of diverse ecosystems and drive global biogeochemical cycles. Cross-fed nutrients within these systems can be either waste products valued by only one partner or nutrients valued by both partners. Here, we explored how interpartner competition for a communally valuable cross-fed nutrient impacts mutualism dynamics. We discovered that mutualism stability necessitates that the recipient have a competitive advantage against the producer in obtaining the cross-fed nutrient, provided that the nutrient is generated intracellularly. We propose that the requirement for recipient-biased competition is a general rule for mutualistic coexistence based on the transfer of intracellularly generated, communally valuable resources.
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Goh HMS, Yong MHA, Chong KKL, Kline KA. Model systems for the study of Enterococcal colonization and infection. Virulence 2017; 8:1525-1562. [PMID: 28102784 PMCID: PMC5810481 DOI: 10.1080/21505594.2017.1279766] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/30/2016] [Accepted: 01/04/2017] [Indexed: 02/07/2023] Open
Abstract
Enterococcus faecalis and Enterococcus faecium are common inhabitants of the human gastrointestinal tract, as well as frequent opportunistic pathogens. Enterococci cause a range of infections including, most frequently, infections of the urinary tract, catheterized urinary tract, bloodstream, wounds and surgical sites, and heart valves in endocarditis. Enterococcal infections are often biofilm-associated, polymicrobial in nature, and resistant to antibiotics of last resort. Understanding Enterococcal mechanisms of colonization and pathogenesis are important for identifying new ways to manage and intervene with these infections. We review vertebrate and invertebrate model systems applied to study the most common E. faecalis and E. faecium infections, with emphasis on recent findings examining Enterococcal-host interactions using these models. We discuss strengths and shortcomings of each model, propose future animal models not yet applied to study mono- and polymicrobial infections involving E. faecalis and E. faecium, and comment on the significance of anti-virulence strategies derived from a fundamental understanding of host-pathogen interactions in model systems.
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Affiliation(s)
- H. M. Sharon Goh
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - M. H. Adeline Yong
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - Kelvin Kian Long Chong
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate School, Nanyang Technological University, Singapore
| | - Kimberly A. Kline
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
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Anderson CJ, Kendall MM. Salmonella enterica Serovar Typhimurium Strategies for Host Adaptation. Front Microbiol 2017; 8:1983. [PMID: 29075247 PMCID: PMC5643478 DOI: 10.3389/fmicb.2017.01983] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 09/26/2017] [Indexed: 12/21/2022] Open
Abstract
Bacterial pathogens must sense and respond to newly encountered host environments to regulate the expression of critical virulence factors that allow for niche adaptation and successful colonization. Among bacterial pathogens, non-typhoidal serovars of Salmonella enterica, such as serovar Typhimurium (S. Tm), are a primary cause of foodborne illnesses that lead to hospitalizations and deaths worldwide. S. Tm causes acute inflammatory diarrhea that can progress to invasive systemic disease in susceptible patients. The gastrointestinal tract and intramacrophage environments are two critically important niches during S. Tm infection, and each presents unique challenges to limit S. Tm growth. The intestinal tract is home to billions of commensal microbes, termed the microbiota, which limits the amount of available nutrients for invading pathogens such as S. Tm. Therefore, S. Tm encodes strategies to manipulate the commensal population and side-step this nutritional competition. During subsequent stages of disease, S. Tm resists host immune cell mechanisms of killing. Host cells use antimicrobial peptides, acidification of vacuoles, and nutrient limitation to kill phagocytosed microbes, and yet S. Tm is able to subvert these defense systems. In this review, we discuss recently described molecular mechanisms that S. Tm uses to outcompete the resident microbiota within the gastrointestinal tract. S. Tm directly eliminates close competitors via bacterial cell-to-cell contact as well as by stimulating a host immune response to eliminate specific members of the microbiota. Additionally, S. Tm tightly regulates the expression of key virulence factors that enable S. Tm to withstand host immune defenses within macrophages. Additionally, we highlight the chemical and physical signals that S. Tm senses as cues to adapt to each of these environments. These strategies ultimately allow S. Tm to successfully adapt to these two disparate host environments. It is critical to better understand bacterial adaptation strategies because disruption of these pathways and mechanisms, especially those shared by multiple pathogens, may provide novel therapeutic intervention strategies.
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Affiliation(s)
- Christopher J Anderson
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine,, Charlottesville, VA, United States
| | - Melissa M Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine,, Charlottesville, VA, United States
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Ford CA, Cassat JE. Advances in the local and targeted delivery of anti-infective agents for management of osteomyelitis. Expert Rev Anti Infect Ther 2017; 15:851-860. [PMID: 28837368 DOI: 10.1080/14787210.2017.1372192] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Osteomyelitis, a common and debilitating invasive infection of bone, is a frequent complication following orthopedic surgery and causes pathologic destruction of skeletal tissues. Bone destruction during osteomyelitis results in necrotic tissue, which is poorly penetrated by antibiotics and can serve as a nidus for relapsing infection. Osteomyelitis therefore frequently necessitates surgical debridement procedures, which provide a unique opportunity for targeted delivery of antimicrobial and adjunctive therapies. Areas covered: Following surgical debridement, tissue voids require implanted materials to facilitate the healing process. Antibiotic-loaded, non-biodegradable implants have been the standard of care. However, a new generation of biodegradable, osteoconductive materials are being developed. Additionally, in the face of widespread antimicrobial resistance, alternative therapies to traditional antibiotic regimens are being investigated, including bone targeting compounds, antimicrobial surface modifications of orthopedic implants, and anti-virulence strategies. Expert commentary: Recent advances in biodegradable drug delivery scaffolds make this technology an attractive alternative to traditional techniques for orthopedic infection that require secondary operations for removal. Advances in novel treatment methods are expanding the arsenal of viable antimicrobial treatment strategies in the face of widespread drug resistance. Despite a need for large scale clinical investigations, these strategies offer hope for future treatment of this difficult invasive disease.
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Affiliation(s)
- Caleb A Ford
- a Department of Biomedical Engineering , Vanderbilt University School of Engineering, Vanderbilt University School of Medicine , Nashville , TN , USA
| | - James E Cassat
- b Departments of Pediatrics, Pathology, Microbiology, and Immunology, and Biomedical Engineering , Vanderbilt University Medical Center , Nashville , TN , USA
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McCully AL, LaSarre B, McKinlay JB. Growth-independent cross-feeding modifies boundaries for coexistence in a bacterial mutualism. Environ Microbiol 2017; 19:3538-3550. [PMID: 28654212 DOI: 10.1111/1462-2920.13847] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/19/2017] [Accepted: 06/22/2017] [Indexed: 11/27/2022]
Abstract
Nutrient cross-feeding can stabilize microbial mutualisms, including those important for carbon cycling in nutrient-limited anaerobic environments. It remains poorly understood how nutrient limitation within natural environments impacts mutualist growth, cross-feeding levels and ultimately mutualism dynamics. We examined the effects of nutrient limitation within a mutualism using theoretical and experimental approaches with a synthetic anaerobic coculture pairing fermentative Escherichia coli and phototrophic Rhodopseudomonas palustris. In this coculture, E. coli and R. palustris resemble an anaerobic food web by cross-feeding essential carbon (organic acids) and nitrogen (ammonium) respectively. Organic acid cross-feeding stemming from E. coli fermentation can continue in a growth-independent manner during nitrogen limitation, while ammonium cross-feeding by R. palustris is growth-dependent. When ammonium cross-feeding was limited, coculture trends changed yet coexistence persisted under both homogenous and heterogenous conditions. Theoretical modelling indicated that growth-independent fermentation was crucial to sustain cooperative growth under conditions of low nutrient exchange. In contrast to stabilization at most cell densities, growth-independent fermentation inhibited mutualistic growth when the E. coli cell density was adequately high relative to that of R. palustris. Thus, growth-independent fermentation can conditionally stabilize or destabilize a mutualism, indicating the potential importance of growth-independent metabolism for nutrient-limited mutualistic communities.
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Affiliation(s)
| | - Breah LaSarre
- Department of Biology, Indiana University, Bloomington, IN, USA
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Mouse model of hematogenous implant-related Staphylococcus aureus biofilm infection reveals therapeutic targets. Proc Natl Acad Sci U S A 2017; 114:E5094-E5102. [PMID: 28607050 DOI: 10.1073/pnas.1703427114] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infection is a major complication of implantable medical devices, which provide a scaffold for biofilm formation, thereby reducing susceptibility to antibiotics and complicating treatment. Hematogenous implant-related infections following bacteremia are particularly problematic because they can occur at any time in a previously stable implant. Herein, we developed a model of hematogenous infection in which an orthopedic titanium implant was surgically placed in the legs of mice followed 3 wk later by an i.v. exposure to Staphylococcus aureus This procedure resulted in a marked propensity for a hematogenous implant-related infection comprised of septic arthritis, osteomyelitis, and biofilm formation on the implants in the surgical legs compared with sham-operated surgical legs without implant placement and with contralateral nonoperated normal legs. Neutralizing human monoclonal antibodies against α-toxin (AT) and clumping factor A (ClfA), especially in combination, inhibited biofilm formation in vitro and the hematogenous implant-related infection in vivo. Our findings suggest that AT and ClfA are pathogenic factors that could be therapeutically targeted against Saureus hematogenous implant-related infections.
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Geisinger E, Isberg RR. Interplay Between Antibiotic Resistance and Virulence During Disease Promoted by Multidrug-Resistant Bacteria. J Infect Dis 2017; 215:S9-S17. [PMID: 28375515 DOI: 10.1093/infdis/jiw402] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Diseases caused by antibiotic-resistant bacteria in hospitals are the outcome of complex relationships between several dynamic factors, including bacterial pathogenicity, the fitness costs of resistance in the human host, and selective forces resulting from interventions such as antibiotic therapy. The emergence and fate of mutations that drive antibiotic resistance are governed by these interactions. In this review, we will examine how different forms of antibiotic resistance modulate bacterial fitness and virulence potential, thus influencing the ability of pathogens to evolve in the context of nosocomial infections. We will focus on 3 important multidrug-resistant pathogens that are notoriously problematic in hospitals: Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus. An understanding of how antibiotic resistance mutations shape the pathobiology of multidrug-resistant infections has the potential to drive novel strategies that can control the development and spread of drug resistance.
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Affiliation(s)
- Edward Geisinger
- Howard Hughes Medical Institute, and.,Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Ralph R Isberg
- Howard Hughes Medical Institute, and.,Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
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Abstract
Transition metals are required trace elements for all forms of life. Due to their unique inorganic and redox properties, transition metals serve as cofactors for enzymes and other proteins. In bacterial pathogenesis, the vertebrate host represents a rich source of nutrient metals, and bacteria have evolved diverse metal acquisition strategies. Host metal homeostasis changes dramatically in response to bacterial infections, including production of metal sequestering proteins and the bombardment of bacteria with toxic levels of metals. In response, bacteria have evolved systems to subvert metal sequestration and toxicity. The coevolution of hosts and their bacterial pathogens in the battle for metals has uncovered emerging paradigms in social microbiology, rapid evolution, host specificity, and metal homeostasis across domains. This review focuses on recent advances and open questions in our understanding of the complex role of transition metals at the host-pathogen interface.
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Affiliation(s)
- Lauren D Palmer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37212;
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37212;
- Tennessee Valley Healthcare System, US Department of Veterans Affairs, Nashville, Tennessee 37212
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Clinical Significance and Pathogenesis of Staphylococcal Small Colony Variants in Persistent Infections. Clin Microbiol Rev 2016; 29:401-27. [PMID: 26960941 DOI: 10.1128/cmr.00069-15] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Small colony variants (SCVs) were first described more than 100 years ago for Staphylococcus aureus and various coagulase-negative staphylococci. Two decades ago, an association between chronic staphylococcal infections and the presence of SCVs was observed. Since then, many clinical studies and observations have been published which tie recurrent, persistent staphylococcal infections, including device-associated infections, bone and tissue infections, and airway infections of cystic fibrosis patients, to this special phenotype. By their intracellular lifestyle, SCVs exhibit so-called phenotypic (or functional) resistance beyond the classical resistance mechanisms, and they can often be retrieved from therapy-refractory courses of infection. In this review, the various clinical infections where SCVs can be expected and isolated, diagnostic procedures for optimized species confirmation, and the pathogenesis of SCVs, including defined underlying molecular mechanisms and the phenotype switch phenomenon, are presented. Moreover, relevant animal models and suggested treatment regimens, as well as the requirements for future research areas, are highlighted.
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Choby JE, Skaar EP. Heme Synthesis and Acquisition in Bacterial Pathogens. J Mol Biol 2016; 428:3408-28. [PMID: 27019298 PMCID: PMC5125930 DOI: 10.1016/j.jmb.2016.03.018] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis.
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Affiliation(s)
- Jacob E Choby
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA; Tennessee Valley Healthcare System, U.S. Department of Veterans Affairs, Nashville, TN, USA.
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Repurposing the Nonsteroidal Anti-inflammatory Drug Diflunisal as an Osteoprotective, Antivirulence Therapy for Staphylococcus aureus Osteomyelitis. Antimicrob Agents Chemother 2016; 60:5322-30. [PMID: 27324764 DOI: 10.1128/aac.00834-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/16/2016] [Indexed: 02/05/2023] Open
Abstract
Staphylococcus aureus osteomyelitis is a common and debilitating invasive infection of bone. Treatment of osteomyelitis is confounded by widespread antimicrobial resistance and the propensity of bacteria to trigger pathological changes in bone remodeling that limit antimicrobial penetration to the infectious focus. Adjunctive therapies that limit pathogen-induced bone destruction could therefore limit morbidity and enhance traditional antimicrobial therapies. In this study, we evaluate the efficacy of the U.S. Food and Drug Administration-approved, nonsteroidal anti-inflammatory (NSAID) compound diflunisal in limiting S. aureus cytotoxicity toward skeletal cells and in preventing bone destruction during staphylococcal osteomyelitis. Diflunisal is known to inhibit S. aureus virulence factor production by the accessory gene regulator (agr) locus, and we have previously demonstrated that the Agr system plays a substantial role in pathological bone remodeling during staphylococcal osteomyelitis. Consistent with these observations, we find that diflunisal potently inhibits osteoblast cytotoxicity caused by S. aureus secreted toxins independently of effects on bacterial growth. Compared to commonly used NSAIDs, diflunisal is uniquely potent in the inhibition of skeletal cell death in vitro Moreover, local delivery of diflunisal by means of a drug-eluting, bioresorbable foam significantly limits bone destruction during S. aureus osteomyelitis in vivo Collectively, these data demonstrate that diflunisal potently inhibits skeletal cell death and bone destruction associated with S. aureus infection and may therefore be a useful adjunctive therapy for osteomyelitis.
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Impact of sarA and Phenol-Soluble Modulins on the Pathogenesis of Osteomyelitis in Diverse Clinical Isolates of Staphylococcus aureus. Infect Immun 2016; 84:2586-94. [PMID: 27354444 DOI: 10.1128/iai.00152-16] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/18/2016] [Indexed: 12/21/2022] Open
Abstract
We used a murine model of acute, posttraumatic osteomyelitis to evaluate the virulence of two divergent Staphylococcus aureus clinical isolates (the USA300 strain LAC and the USA200 strain UAMS-1) and their isogenic sarA mutants. The results confirmed that both strains caused comparable degrees of osteolysis and reactive new bone formation in the acute phase of osteomyelitis. Conditioned medium (CM) from stationary-phase cultures of both strains was cytotoxic to cells of established cell lines (MC3TC-E1 and RAW 264.7 cells), primary murine calvarial osteoblasts, and bone marrow-derived osteoclasts. Both the cytotoxicity of CM and the reactive changes in bone were significantly reduced in the isogenic sarA mutants. These results confirm that sarA is required for the production and/or accumulation of extracellular virulence factors that limit osteoblast and osteoclast viability and that thereby promote bone destruction and reactive bone formation during the acute phase of S. aureus osteomyelitis. Proteomic analysis confirmed the reduced accumulation of multiple extracellular proteins in the LAC and UAMS-1 sarA mutants. Included among these were the alpha class of phenol-soluble modulins (PSMs), which were previously implicated as important determinants of osteoblast cytotoxicity and bone destruction and repair processes in osteomyelitis. Mutation of the corresponding operon reduced the cytotoxicity of CM from both UAMS-1 and LAC cultures for osteoblasts and osteoclasts. It also significantly reduced both reactive bone formation and cortical bone destruction by CM from LAC cultures. However, this was not true for CM from cultures of a UAMS-1 psmα mutant, thereby suggesting the involvement of additional virulence factors in such strains that remain to be identified.
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Franza T, Delavenne E, Derré-Bobillot A, Juillard V, Boulay M, Demey E, Vinh J, Lamberet G, Gaudu P. A partial metabolic pathway enables group b streptococcus to overcome quinone deficiency in a host bacterial community. Mol Microbiol 2016; 102:81-91. [PMID: 27328751 DOI: 10.1111/mmi.13447] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2016] [Indexed: 11/28/2022]
Abstract
Aerobic respiration metabolism in Group B Streptococcus (GBS) is activated by exogenous heme and menaquinone. This capacity enhances resistance of GBS to acid and oxidative stress and improves its survival. In this work, we discovered that GBS is able to respire in the presence of heme and 1,4-dihydroxy-2-naphthoic acid (DHNA). DHNA is a biosynthetic precursor of demethylmenaquinone (DMK) in many bacterial species. A GBS gene (gbs1789) encodes a homolog of the MenA 1,4-dihydroxy-2-naphthoate prenyltransferase enzyme, involved in the synthesis of demethylmenaquinone. In this study, we showed that gbs1789 is involved in the biosynthesis of long-chain demethylmenaquinones (DMK-10). The Δgbs1789 mutant cannot respire in the presence of heme and DHNA, indicating that endogenously synthesized DMKs are cofactors of the GBS respiratory chain. We also found that isoprenoid side chains from GBS DMKs are produced by the protein encoded by the gbs1783 gene, since this gene can complement an Escherichia coli ispB mutant defective for isoprenoids chain synthesis. In the gut or vaginal microbiote, where interspecies metabolite exchanges occur, this partial DMK biosynthetic pathway can be important for GBS respiration and survival in different niches.
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Affiliation(s)
- Thierry Franza
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France.
| | - Emilie Delavenne
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Aurélie Derré-Bobillot
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Vincent Juillard
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Mylène Boulay
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | | | - Joelle Vinh
- ESPCI Paris, SMBP USR3149 CNRS, Paris, F-75005, France
| | - Gilles Lamberet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Philippe Gaudu
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
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A novel nitro-dexamethasone inhibits agr system activity and improves therapeutic effects in MRSA sepsis models without antibiotics. Sci Rep 2016; 6:20307. [PMID: 26839286 PMCID: PMC4738243 DOI: 10.1038/srep20307] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/30/2015] [Indexed: 12/13/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) sepsis is a life-threatening medical condition that involves systemic inflammation throughout the body. Glucocorticoids are widely used in combination with antibiotics in the treatment of MRSA sepsis to fight the overwhelming inflammation. Here, we describe the improved anti-inflammatory properties of a nitric oxide (NO)-releasing derivative of dexamethasone, ND8008. ND8008 affected MRSA biofilm formation, caused biofilm cell death, and reduced the effects of virulence factors, such as α-toxin, by inhibiting the activity of the Staphylococcus aureus accessory gene regulator (agr) system. Dosing of mice with ND8008 (127.4 nmol/kg, i.p.) alone greatly reduced the inflammatory response caused by MRSA blood stream infection and considerably increased the survival rate of septic mice. These findings suggest that this novel NO-releasing derivative of dexamethasone ND8008 could be helpful in the treatment of MRSA sepsis.
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Abstract
Microbes are now known to participate in an extensive repertoire of cooperative behaviors such as biofilm formation, production of extracellular public-goods, group motility, and higher-ordered multicellular structures. A fundamental question is how these cooperative tasks are maintained in the face of non-cooperating defector cells. Recently, a number of molecular mechanisms including facultative participation, spatial sorting, and policing have been discovered to stabilize cooperation. Often these different mechanisms work in concert to reinforce cooperation. In this review, we describe bacterial cooperation and the current understanding of the molecular mechanisms that maintain it.
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Affiliation(s)
- Eric Bruger
- Department of Microbiology and Molecular Genetics and the BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, 48824, USA
| | - Christopher Waters
- Department of Microbiology and Molecular Genetics and the BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, 48824, USA
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Wilde AD, Snyder DJ, Putnam NE, Valentino MD, Hammer ND, Lonergan ZR, Hinger SA, Aysanoa EE, Blanchard C, Dunman PM, Wasserman GA, Chen J, Shopsin B, Gilmore MS, Skaar EP, Cassat JE. Bacterial Hypoxic Responses Revealed as Critical Determinants of the Host-Pathogen Outcome by TnSeq Analysis of Staphylococcus aureus Invasive Infection. PLoS Pathog 2015; 11:e1005341. [PMID: 26684646 PMCID: PMC4684308 DOI: 10.1371/journal.ppat.1005341] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/23/2015] [Indexed: 12/11/2022] Open
Abstract
Staphylococcus aureus is capable of infecting nearly every organ in the human body. In order to infiltrate and thrive in such diverse host tissues, staphylococci must possess remarkable flexibility in both metabolic and virulence programs. To investigate the genetic requirements for bacterial survival during invasive infection, we performed a transposon sequencing (TnSeq) analysis of S. aureus during experimental osteomyelitis. TnSeq identified 65 genes essential for staphylococcal survival in infected bone and an additional 148 mutants with compromised fitness in vivo. Among the loci essential for in vivo survival was SrrAB, a staphylococcal two-component system previously reported to coordinate hypoxic and nitrosative stress responses in vitro. Healthy bone is intrinsically hypoxic, and intravital oxygen monitoring revealed further decreases in skeletal oxygen concentrations upon S. aureus infection. The fitness of an srrAB mutant during osteomyelitis was significantly increased by depletion of neutrophils, suggesting that neutrophils impose hypoxic and/or nitrosative stresses on invading bacteria. To more globally evaluate staphylococcal responses to changing oxygenation, we examined quorum sensing and virulence factor production in staphylococci grown under aerobic or hypoxic conditions. Hypoxic growth resulted in a profound increase in quorum sensing-dependent toxin production, and a concomitant increase in cytotoxicity toward mammalian cells. Moreover, aerobic growth limited quorum sensing and cytotoxicity in an SrrAB-dependent manner, suggesting a mechanism by which S. aureus modulates quorum sensing and toxin production in response to environmental oxygenation. Collectively, our results demonstrate that bacterial hypoxic responses are key determinants of the staphylococcal-host interaction.
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Affiliation(s)
- Aimee D. Wilde
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Daniel J. Snyder
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Nicole E. Putnam
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Michael D. Valentino
- Departments of Ophthalmology and Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Neal D. Hammer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Zachery R. Lonergan
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Scott A. Hinger
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Esar E. Aysanoa
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Catlyn Blanchard
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Paul M. Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Gregory A. Wasserman
- Departments of Medicine and Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - John Chen
- Skirball Institute Program in Molecular Pathogenesis, Departments of Microbiology and Medicine, New York University Medical Center, New York, New York, United States of America
| | - Bo Shopsin
- Departments of Medicine and Microbiology, New York University School of Medicine, New York, New York, United States of America
| | - Michael S. Gilmore
- Departments of Ophthalmology and Microbiology and Immunology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare Services, Nashville, Tennessee, United States of America
| | - James E. Cassat
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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45
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Abstract
Ancient bacteria originated from metal-rich environments. Billions of years of evolution directed these tiny single cell creatures to exploit the versatile properties of metals in catalyzing chemical reactions and biological responses. The result is an entire metallome of proteins that use metal co-factors to facilitate key cellular process that range from the production of energy to the replication of DNA. Two key metals in this regard are iron and zinc, both abundant on Earth but not readily accessible in a human host. Instead, pathogenic bacteria must employ clever ways to acquire these metals. In this review we describe the many elegant ways these bacteria mine, regulate, and craft the use of two key metals (iron and zinc) to build a virulence arsenal that challenges even the most sophisticated immune response.
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Affiliation(s)
- Li Ma
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77459, USA.
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46
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Abstract
Recent studies are revealing astonishing heterogeneity in host-pathogen interactions occurring simultaneously within the same host tissue. As highlighted in this review, growing knowledge of the in vivo complexity is altering our understanding of infection biology. In particular, pathogen subsets reside in diverse tissue microenvironments and detect and respond to local conditions. The individual pathogen-host encounters have disparate outcomes, depending on differential molecular interactions. As a result, disease progression can result from failure to control individual infection foci, despite successful eradication of others, and antibiotic therapy can be delayed by distinct pre-existing pathogen subsets. Together, these data are unraveling rich biology with implications for infectious disease progression and control.
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Affiliation(s)
- Dirk Bumann
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland.
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47
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Biggs MB, Medlock GL, Kolling GL, Papin JA. Metabolic network modeling of microbial communities. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2015; 7:317-34. [PMID: 26109480 DOI: 10.1002/wsbm.1308] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/07/2015] [Accepted: 05/13/2015] [Indexed: 12/15/2022]
Abstract
Genome-scale metabolic network reconstructions and constraint-based analyses are powerful methods that have the potential to make functional predictions about microbial communities. Genome-scale metabolic networks are used to characterize the metabolic functions of microbial communities via several techniques including species compartmentalization, separating species-level and community-level objectives, dynamic analysis, the 'enzyme-soup' approach, multiscale modeling, and others. There are many challenges in the field, including a need for tools that accurately assign high-level omics signals to individual community members, the need for improved automated network reconstruction methods, and novel algorithms for integrating omics data and engineering communities. As technologies and modeling frameworks improve, we expect that there will be corresponding advances in the fields of ecology, health science, and microbial community engineering.
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Affiliation(s)
- Matthew B Biggs
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Gregory L Medlock
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Glynis L Kolling
- Department of Medicine, Infectious Diseases, University of Virginia, Charlottesville, VA, USA
| | - Jason A Papin
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
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48
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Abstract
In this issue of Cell Host & Microbe, Hammer et al. (2014) show that distinct, slow-growing bacteria have better in vitro and in vivo growth and virulence when cocultured than in isolation. They provide evidence that the observed inter- and intraspecies "complementation" involves the intercellular exchange of metabolites.
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Affiliation(s)
- Daniel J Wolter
- Department of Pediatrics, University of Washington, Seattle, Seattle, WA 98195, USA
| | - Lucas R Hoffman
- Department of Pediatrics, University of Washington, Seattle, Seattle, WA 98195, USA; Department of Microbiology, University of Washington, Seattle, Seattle, WA 98195, USA.
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49
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Amorim-Vaz S, Delarze E, Ischer F, Sanglard D, Coste AT. Examining the virulence of Candida albicans transcription factor mutants using Galleria mellonella and mouse infection models. Front Microbiol 2015; 6:367. [PMID: 25999923 PMCID: PMC4419840 DOI: 10.3389/fmicb.2015.00367] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 04/10/2015] [Indexed: 01/08/2023] Open
Abstract
The aim of the present study was to identify Candida albicans transcription factors (TFs) involved in virulence. Although mice are considered the gold-standard model to study fungal virulence, mini-host infection models have been increasingly used. Here, barcoded TF mutants were first screened in mice by pools of strains and fungal burdens (FBs) quantified in kidneys. Mutants of unannotated genes which generated a kidney FB significantly different from that of wild-type were selected and individually examined in Galleria mellonella. In addition, mutants that could not be detected in mice were also tested in G. mellonella. Only 25% of these mutants displayed matching phenotypes in both hosts, highlighting a significant discrepancy between the two models. To address the basis of this difference (pool or host effects), a set of 19 mutants tested in G. mellonella were also injected individually into mice. Matching FB phenotypes were observed in 50% of the cases, highlighting the bias due to host effects. In contrast, 33.4% concordance was observed between pool and single strain infections in mice, thereby highlighting the bias introduced by the "pool effect." After filtering the results obtained from the two infection models, mutants for MBF1 and ZCF6 were selected. Independent marker-free mutants were subsequently tested in both hosts to validate previous results. The MBF1 mutant showed impaired infection in both models, while the ZCF6 mutant was only significant in mice infections. The two mutants showed no obvious in vitro phenotypes compared with the wild-type, indicating that these genes might be specifically involved in in vivo adapt.
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Affiliation(s)
- Sara Amorim-Vaz
- Institute of Microbiology, University of Lausanne and University Hospital of Lausanne Lausanne, Switzerland
| | - Eric Delarze
- Institute of Microbiology, University of Lausanne and University Hospital of Lausanne Lausanne, Switzerland
| | - Françoise Ischer
- Institute of Microbiology, University of Lausanne and University Hospital of Lausanne Lausanne, Switzerland
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital of Lausanne Lausanne, Switzerland
| | - Alix T Coste
- Institute of Microbiology, University of Lausanne and University Hospital of Lausanne Lausanne, Switzerland
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