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Woodcock SD, Syson K, Little RH, Ward D, Sifouna D, Brown JKM, Bornemann S, Malone JG. Trehalose and α-glucan mediate distinct abiotic stress responses in Pseudomonas aeruginosa. PLoS Genet 2021; 17:e1009524. [PMID: 33872310 PMCID: PMC8084333 DOI: 10.1371/journal.pgen.1009524] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/29/2021] [Accepted: 03/30/2021] [Indexed: 11/29/2022] Open
Abstract
An important prelude to bacterial infection is the ability of a pathogen to survive independently of the host and to withstand environmental stress. The compatible solute trehalose has previously been connected with diverse abiotic stress tolerances, particularly osmotic shock. In this study, we combine molecular biology and biochemistry to dissect the trehalose metabolic network in the opportunistic human pathogen Pseudomonas aeruginosa PAO1 and define its role in abiotic stress protection. We show that trehalose metabolism in PAO1 is integrated with the biosynthesis of branched α-glucan (glycogen), with mutants in either biosynthetic pathway significantly compromised for survival on abiotic surfaces. While both trehalose and α-glucan are important for abiotic stress tolerance, we show they counter distinct stresses. Trehalose is important for the PAO1 osmotic stress response, with trehalose synthesis mutants displaying severely compromised growth in elevated salt conditions. However, trehalose does not contribute directly to the PAO1 desiccation response. Rather, desiccation tolerance is mediated directly by GlgE-derived α-glucan, with deletion of the glgE synthase gene compromising PAO1 survival in low humidity but having little effect on osmotic sensitivity. Desiccation tolerance is independent of trehalose concentration, marking a clear distinction between the roles of these two molecules in mediating responses to abiotic stress. Author summary To survive outside their host, pathogenic bacteria must withstand various environmental stresses. The sugar molecule trehalose is associated with a range of abiotic stress tolerances, particularly osmotic shock. In this study, we analyse the trehalose metabolic network in the human pathogen Pseudomonas aeruginosa PAO1 and define its role in abiotic stress protection. We show that trehalose metabolism in PAO1 is intimately connected to the biosynthesis of branched α-glucan, or glycogen. Disruption of either trehalose or glycogen biosynthesis significantly reduces the ability of PAO1 to survive on steel work surfaces. While both trehalose and glycogen are important for stress tolerance, they counter very different stresses. Trehalose is important for the osmotic stress response, and survival in conditions of elevated salt. On the other hand, glycogen is responsible for desiccation tolerance and survival in low humidity environments. Trehalose does not apparently contribute to desiccation tolerance, marking a clear distinction between the roles of trehalose and glycogen in mediating abiotic stress responses in P. aeruginosa.
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Affiliation(s)
- Stuart D. Woodcock
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Karl Syson
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Richard H. Little
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Danny Ward
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Despoina Sifouna
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - James K. M. Brown
- Department of Crop Genetics, John Innes Centre, Norwich, United Kingdom
| | - Stephen Bornemann
- Department of Biological Chemistry, John Innes Centre, Norwich, United Kingdom
| | - Jacob G. Malone
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
- * E-mail:
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Heirali A, McKeon S, Purighalla S, Storey DG, Rossi L, Costilhes G, Drews SJ, Rabin HR, Surette MG, Parkins MD. Assessment of the Microbial Constituents of the Home Environment of Individuals with Cystic Fibrosis (CF) and Their Association with Lower Airways Infections. PLoS One 2016; 11:e0148534. [PMID: 26859493 PMCID: PMC4747485 DOI: 10.1371/journal.pone.0148534] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/19/2016] [Indexed: 02/01/2023] Open
Abstract
INTRODUCTION Cystic fibrosis (CF) airways are colonized by a polymicrobial community of organisms, termed the CF microbiota. We sought to define the microbial constituents of the home environment of individuals with CF and determine if it may serve as a latent reservoir for infection. METHODS Six patients with newly identified CF pathogens were included. An investigator collected repeat sputum and multiple environmental samples from their homes. Bacteria were cultured under both aerobic and anaerobic conditions. Morphologically distinct colonies were selected, purified and identified to the genus and species level through 16S rRNA gene sequencing. When concordant organisms were identified in sputum and environment, pulsed-field gel electrophoresis (PFGE) was performed to determine relatedness. Culture-independent bacterial profiling of each sample was carried out by Illumina sequencing of the V3 region of the 16s RNA gene. RESULTS New respiratory pathogens prompting investigation included: Mycobacterium abscessus(2), Stenotrophomonas maltophilia(3), Pseudomonas aeruginosa(3), Pseudomonas fluorescens(1), Nocardia spp.(1), and Achromobacter xylosoxidans(1). A median 25 organisms/patient were cultured from sputum. A median 125 organisms/home were cultured from environmental sites. Several organisms commonly found in the CF lung microbiome were identified within the home environments of these patients. Concordant species included members of the following genera: Brevibacterium(1), Microbacterium(1), Staphylococcus(3), Stenotrophomonas(2), Streptococcus(2), Sphingomonas(1), and Pseudomonas(4). PFGE confirmed related strains (one episode each of Sphinogomonas and P. aeruginosa) from the environment and airways were identified in two patients. Culture-independent assessment confirmed that many organisms were not identified using culture-dependent techniques. CONCLUSIONS Members of the CF microbiota can be found as constituents of the home environment in individuals with CF. While the majority of isolates from the home environment were not genetically related to those isolated from the lower airways of individuals with CF suggesting alternate sources of infection were more common, a few genetically related isolates were indeed identified. As such, the home environment may rarely serve as either the source of infection or a persistent reservoir for re-infection after clearance.
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Affiliation(s)
- Alya Heirali
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Suzanne McKeon
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
| | - Swathi Purighalla
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
| | - Douglas G. Storey
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Laura Rossi
- The Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Geoffrey Costilhes
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
| | - Steven J. Drews
- Department of Laboratory Medicine & Pathology, University of Alberta, Edmonton, AB, Canada
| | - Harvey R. Rabin
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- Department of Medicine, The University of Calgary, Calgary, AB, Canada
| | - Michael G. Surette
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- The Department of Biochemistry & Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Michael D. Parkins
- Department of Microbiology Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- Department of Medicine, The University of Calgary, Calgary, AB, Canada
- * E-mail:
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Gautam V, Shafiq N, Singh M, Ray P, Singhal L, Jaiswal NP, Prasad A, Singh S, Agarwal A. Clinical and in vitro evidence for the antimicrobial therapy in Burkholderia cepacia complex infections. Expert Rev Anti Infect Ther 2015; 13:629-63. [PMID: 25772031 DOI: 10.1586/14787210.2015.1025056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Treatment of infections caused by Burkholderia cepacia complex (Bcc) in cystic fibrosis (CF) patients poses a complex problem. Bcc is multidrug-resistant due to innate and acquired mechanisms of resistance. As CF patients receive multiple courses of antibiotics, susceptibility patterns of strains from CF patients may differ from those noted in strains from non-CF patients. Thus, there was a need for assessing in vitro and clinical data to guide antimicrobial therapy in these patients. A systematic search of literature, followed by extraction and analysis of available information from human and in vitro studies was done. The results of the analysis are used to address various aspects like use of antimicrobials for pulmonary and non-pulmonary infections, use of combination versus monotherapy, early eradication, duration of therapy, route of administration, management of biofilms, development of resistance during therapy, pharmacokinetics-pharmacodynamics correlations, therapy in post-transplant patients and newer drugs in Bcc-infected CF patients.
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Affiliation(s)
- Vikas Gautam
- Deparatment of Medical Microbiology, PGIMER, Chandigarh 160022, India
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Wiehlmann L, Cramer N, Ulrich J, Hedtfeld S, Weißbrodt H, Tümmler B. Effective prevention of Pseudomonas aeruginosa cross-infection at a cystic fibrosis centre – Results of a 10-year prospective study. Int J Med Microbiol 2012; 302:69-77. [DOI: 10.1016/j.ijmm.2011.11.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/04/2011] [Accepted: 11/06/2011] [Indexed: 11/28/2022] Open
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Horsley A, Webb K, Bright-Thomas R, Govan J, Jones A. Can early Burkholderia cepacia complex infection in cystic fibrosis be eradicated with antibiotic therapy? Front Cell Infect Microbiol 2011; 1:18. [PMID: 22919584 PMCID: PMC3417365 DOI: 10.3389/fcimb.2011.00018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 11/30/2011] [Indexed: 11/13/2022] Open
Abstract
Introduction: Organisms of the Burkholderia cepacia complex (BCC) are important pathogens in cystic fibrosis (CF). The majority of those who acquire BCC develop chronic infection but it can also result in rapid decline in a significant minority. In addition, chronic infection with Burkholderia cenocepacia in particular is regarded as a contraindication to lung transplantation in many units. Whilst aggressive antibiotic therapy is employed in CF to eradicate Pseudomonas aeruginosa before infection becomes irreversibly established, no formal assessment of such strategies has been previously reported for BCC, despite the apparent widespread adoption of this practice. Methods: UK adult CF centers were surveyed about their current approach to new BCC infection. Outcomes of eradication therapy were assessed in patients attending the Manchester Adult CF Center with new BCC isolates between 1st January 2002 and 1st May 2011. Patients with previous infection with the same strain of BCC were excluded. BCC were identified at the national reference laboratories and confirmed by species-specific PCR and RecA sequencing. Results: Routine use of therapies to attempt eradication of new BCC is commonly used in the UK (12/17 centers who responded). This typically involves a combination of intravenous and nebulised antibiotics. Of 19 eligible cases of new BCC infection, the organism has been eradicated in 7 (37%). Three of these did not receive specific eradication therapy. Of 14 patients who have received eradication therapy and completed follow up, BCC were cleared in only 4 (29%). Conclusions: Attempted eradication of new BCC is a common practice in UK adult CF centers. A minority of patients clear the infection spontaneously and the effects of eradication therapies are at best modest. Early treatment may be associated with better outcomes, though there are insufficient data to support the use of any specific treatment regimen. A prospective, systematic evaluation of treatments and outcomes is required.
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Affiliation(s)
- Alex Horsley
- Manchester Adult Cystic Fibrosis Center, University Hospitals South Manchester Manchester, UK; Respiratory Research Group, School of Translational Medicine, University of Manchester, Manchester, UK.
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Abstract
With more antibiotic resistance and emerging pathogens in cystic fibrosis (CF) patients, the need for new strategies in the lifelong treatment of pulmonary infection has increased. Most of the focus is on chronic infection with Pseudomonas aeruginosa, which is still thought to be the main pathogen leading to advanced CF lung disease. Other bacterial species are also recognized in the pathogenesis of CF lung disease, even though their definitive role is not well established yet. Clearly, expansion of treatment options is urgently needed. This article focuses on recent developments in the field of new antimicrobial strategies for CF. It is clear that studies on new classes of antibiotics or antimicrobial-like drugs are scarce, and that most studies involve new (inhalation) formulations, new routes of delivery, or analogs of existing classes of antibiotics. Studies of new antibiotic-like drugs are, in most cases, in preclinical phases of development and only a few of these agents may reach the market. Importantly, new inhaled antibiotics, e.g. aztreonam, levofloxacin, and fosfomycin, and new, more efficient delivery systems such as dry powder inhalation and liposomes for current antibiotics are in the clinical phase of development. These developments will be of great importance in improving effective treatment and reducing the treatment burden for CF patients in the near future.
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Affiliation(s)
- Mireille van Westreenen
- Department of Medical Microbiology & Infectious Diseases, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, the Netherlands.
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