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Alcàcer-Almansa J, Blanco-Cabra N, Torrents E. Burkholderia cenocepacia and Pseudomonas aeruginosa in dual-species models: Insights into population distribution, antibiotic susceptibility, and virulence. Virulence 2025; 16:2494039. [PMID: 40272017 PMCID: PMC12036490 DOI: 10.1080/21505594.2025.2494039] [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: 11/08/2024] [Revised: 04/03/2025] [Accepted: 04/10/2025] [Indexed: 04/25/2025] Open
Abstract
Multispecies biofilms are communities composed of different microorganisms embedded in an auto-synthesized polymeric matrix. Pseudomonas aeruginosa and Burkholderia cenocepacia are two multidrug-resistant and biofilm-forming opportunistic pathogens often found in the lungs of people living with cystic fibrosis. In this context, planktonic, static, and dynamic biofilms and in vivo models of both species were optimized in this work to understand their population dynamics, disposition, virulence, and antibiotic susceptibility. From the coculture models optimized in this work, we determined that B. cenocepacia grows in a clustered, aggregative manner at the bottom layers of biofilms, in close contact with P. aeruginosa, that tends to occupy the top layers. Their coexistence increases virulence-related gene expression in both species at early stages of coinfection and in in vivo models, while there was a general downregulation of virulence-related genes after longer coexistence periods as they eventually reach a non-competitive stage during chronic infections. When evaluating antimicrobial susceptibility, a decrease of antimicrobial tolerance was observed in both species when co-cultured. These findings shed light on the differential behavior of P. aeruginosa and B. cenocepacia in dual-species systems, stressing the relevance of multispecies studies in the clinical context.
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Affiliation(s)
- Júlia Alcàcer-Almansa
- Bacterial Infections and Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Microbiology Section, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Núria Blanco-Cabra
- Bacterial Infections and Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Microbiology Section, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Eduard Torrents
- Bacterial Infections and Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Microbiology Section, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
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Coulon PML, Groleau MC, Hachani A, Padula MP, Stinear TP, Déziel E. Quorum sensing and DNA methylation play active roles in clinical Burkholderia phase variation. J Bacteriol 2025; 207:e0053124. [PMID: 39950805 PMCID: PMC11925244 DOI: 10.1128/jb.00531-24] [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: 12/16/2024] [Accepted: 12/27/2024] [Indexed: 03/21/2025] Open
Abstract
Phenotypic diversity in bacteria often results from adaptation to changing environmental conditions, exemplified by variable colony morphotypes. In Burkholderia pseudomallei, discrete genomic alterations and modulation of gene expression facilitate adaptation. Adapted variants of species within the Burkholderia cepacia complex (Bcc) often lose the pC3 virulence megaplasmid, impacting their colony morphology and their production of virulence factors. In this study, we characterize variants arising in Burkholderia ambifaria clinical isolates using proteomics and phenotypic tests and show that some of them have retained the pC3, indicating a distinct phase variation mechanism at play in this Bcc species. Interestingly, variants of B. ambifaria strains CEP0996 (pC3-null) and HSJ1 (pC3-positive) still share similarities in phenotypes controlled by the Cep quorum-sensing (QS) system. We further investigated the role of QS in B. ambifaria HSJ1 phase variation and confirmed that the Cep QS system is important for the emergence of variants. Given that DNA methylation is a key epigenetic factor regulating virulence factors in Burkholderia cenocepacia, we hypothesized that adenosine DNA methylation also governs phase variation in B. ambifaria HSJ1. By deleting the genes encoding putative adenosine DNA methyltransferases, we discovered that an orphan type II DNA methyltransferase inhibits the emergence of phase variants. This study is the first to demonstrate that quorum sensing and adenosine DNA methylation are two antagonistic systems independently controlling phase variation in B. ambifaria.IMPORTANCESome Burkholderia species are pathogenic to plants, animals, or humans. In immunocompromised individuals, and people suffering from cystic fibrosis, infection from the Burkholderia cepacia complex (Bcc) can lead to "cepacia syndrome." In northern Australia and southeast Asia, melioidosis caused by Burkholderia pseudomallei is prevalent among native population, particularly among people with diabetes, chronic lung or kidney disease or alcoholism. Burkholderia's phenotypic plasticity, including colony morphotype variation (CMV), enables rapid adaptation to diverse environments, enhancing its survival and pathogenicity. This study reveals phase variation as a new CMV mechanism within the Bcc group and is the first to report that quorum sensing and DNA methylation are involved in phase variation. Understanding the underlying mechanisms of CMV could lead to the development of targeted therapies against these highly antibiotic-tolerant bacteria.
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Affiliation(s)
- Pauline M. L. Coulon
- Australian Institute for Microbiology and Infection, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, Australia
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
- Department of Microbiology and Immunology, Doherty Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Marie-Christine Groleau
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Abderrahman Hachani
- Department of Microbiology and Immunology, Doherty Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Matthew P. Padula
- School of Life Sciences, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Timothy P. Stinear
- Department of Microbiology and Immunology, Doherty Institute, University of Melbourne, Parkville, Victoria, Australia
- Centre for Pathogen Genomics, University of Melbourne, Melbourne, Victoria, Australia
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
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Estevens R, Mil-Homens D, Fialho AM. In-Silico Analysis Highlights the Existence in Members of Burkholderia cepacia Complex of a New Class of Adhesins Possessing Collagen-like Domains. Microorganisms 2023; 11:1118. [PMID: 37317093 DOI: 10.3390/microorganisms11051118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/18/2023] [Accepted: 04/22/2023] [Indexed: 06/16/2023] Open
Abstract
Burkholderia cenocepacia is a multi-drug-resistant lung pathogen. This species synthesizes various virulence factors, among which cell-surface components (adhesins) are critical for establishing the contact with host cells. This work in the first part focuses on the current knowledge about the adhesion molecules described in this species. In the second part, through in silico approaches, we perform a comprehensive analysis of a group of unique bacterial proteins possessing collagen-like domains (CLDs) that are strikingly overrepresented in the Burkholderia species, representing a new putative class of adhesins. We identified 75 CLD-containing proteins in Burkholderia cepacia complex (Bcc) members (Bcc-CLPs). The phylogenetic analysis of Bcc-CLPs revealed the evolution of the core domain denominated "Bacterial collagen-like, middle region". Our analysis remarkably shows that these proteins are formed by extensive sets of compositionally biased residues located within intrinsically disordered regions (IDR). Here, we discuss how IDR functions may increase their efficiency as adhesion factors. Finally, we provided an analysis of a set of five homologs identified in B. cenocepacia J2315. Thus, we propose the existence in Bcc of a new type of adhesion factors distinct from the described collagen-like proteins (CLPs) found in Gram-positive bacteria.
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Affiliation(s)
- Ricardo Estevens
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Dalila Mil-Homens
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Institute for Bioengineering and Biosciences (iBB), Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Institute for Health and Bioeconomic (i4HB), Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Arsenio M Fialho
- Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Institute for Bioengineering and Biosciences (iBB), Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
- Institute for Health and Bioeconomic (i4HB), Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
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Saroha T, Patil PP, Rana R, Kumar R, Kumar S, Singhal L, Gautam V, Patil PB. Genomic features, antimicrobial susceptibility, and epidemiological insights into Burkholderia cenocepacia clonal complex 31 isolates from bloodstream infections in India. Front Cell Infect Microbiol 2023; 13:1151594. [PMID: 37153161 PMCID: PMC10155701 DOI: 10.3389/fcimb.2023.1151594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 03/31/2023] [Indexed: 05/09/2023] Open
Abstract
Introduction Burkholderia cepacia complex (Bcc) clonal complex (CC) 31, the predominant lineage causing devastating outbreaks globally, has been a growing concern of infections in non-cystic fibrosis (NCF) patients in India. B. cenocepacia is very challenging to treat owing to its virulence determinants and antibiotic resistance. Improving the management of these infections requires a better knowledge of their resistance patterns and mechanisms. Methods Whole-genome sequences of 35 CC31 isolates obtained from patient samples, were analyzed against available 210 CC31 genomes in the NCBI database to glean details of resistance, virulence, mobile elements, and phylogenetic markers to study genomic diversity and evolution of CC31 lineage in India. Results Genomic analysis revealed that 35 isolates belonging to CC31 were categorized into 11 sequence types (ST), of which five STs were reported exclusively from India. Phylogenetic analysis classified 245 CC31 isolates into eight distinct clades (I-VIII) and unveiled that NCF isolates are evolving independently from the global cystic fibrosis (CF) isolates forming a distinct clade. The detection rate of seven classes of antibiotic-related genes in 35 isolates was 35 (100%) for tetracyclines, aminoglycosides, and fluoroquinolones; 26 (74.2%) for sulphonamides and phenicols; 7 (20%) for beta-lactamases; and 1 (2.8%) for trimethoprim resistance genes. Additionally, 3 (8.5%) NCF isolates were resistant to disinfecting agents and antiseptics. Antimicrobial susceptibility testing revealed that majority of NCF isolates were resistant to chloramphenicol (77%) and levofloxacin (34%). NCF isolates have a comparable number of virulence genes to CF isolates. A well-studied pathogenicity island of B. cenocepacia, GI11 is present in ST628 and ST709 isolates from the Indian Bcc population. In contrast, genomic island GI15 (highly similar to the island found in B. pseudomallei strain EY1) is exclusively reported in ST839 and ST824 isolates from two different locations in India. Horizontal acquisition of lytic phage ST79 of pathogenic B. pseudomallei is demonstrated in ST628 isolates Bcc1463, Bcc29163, and BccR4654 amongst CC31 lineage. Discussion The study reveals a high diversity of CC31 lineages among B. cenocepacia isolates from India. The extensive information from this study will facilitate the development of rapid diagnostic and novel therapeutic approaches to manage B. cenocepacia infections.
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Affiliation(s)
- Tanu Saroha
- Bacterial Genomics and Evolution Laboratory, Council of Scientific and Industrial Research (CSIR)-Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Prashant P. Patil
- Bacterial Genomics and Evolution Laboratory, Council of Scientific and Industrial Research (CSIR)-Institute of Microbial Technology, Chandigarh, India
| | - Rekha Rana
- Bacterial Genomics and Evolution Laboratory, Council of Scientific and Industrial Research (CSIR)-Institute of Microbial Technology, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Rajesh Kumar
- Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Sanjeet Kumar
- Bacterial Genomics and Evolution Laboratory, Council of Scientific and Industrial Research (CSIR)-Institute of Microbial Technology, Chandigarh, India
| | - Lipika Singhal
- Department of Microbiology, Government Medical College and Hospital, Chandigarh, India
| | - Vikas Gautam
- Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
- *Correspondence: Prabhu B. Patil, ; Vikas Gautam,
| | - Prabhu B. Patil
- Bacterial Genomics and Evolution Laboratory, Council of Scientific and Industrial Research (CSIR)-Institute of Microbial Technology, Chandigarh, India
- *Correspondence: Prabhu B. Patil, ; Vikas Gautam,
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Zaman NR, Chowdhury UF, Reza RN, Chowdhury FT, Sarker M, Hossain MM, Akbor MA, Amin A, Islam MR, Khan H. Plant growth promoting endophyte Burkholderia contaminans NZ antagonizes phytopathogen Macrophomina phaseolina through melanin synthesis and pyrrolnitrin inhibition. PLoS One 2021; 16:e0257863. [PMID: 34591915 PMCID: PMC8483353 DOI: 10.1371/journal.pone.0257863] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 09/14/2021] [Indexed: 11/23/2022] Open
Abstract
The endophytic bacterium Burkholderia contaminans NZ was isolated from jute, which is an important fiber-producing plant. This bacterium exhibits significant growth promotion activity in in vivo pot experiments, and like other plant growth-promoting (PGP) bacteria fixes nitrogen, produces indole acetic acid (IAA), siderophore, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. B. contaminans NZ is considered to exert a promising growth inhibitory effect on Macrophomina phaseolina, a phytopathogen responsible for infecting hundreds of crops worldwide. This study aimed to identify the possibility of B. contaminans NZ as a safe biocontrol agent and assess its effectiveness in suppressing phytopathogenic fungi, especially M. phaseolina. Co-culture of M. phaseolina with B. contaminans NZ on both solid and liquid media revealed appreciable growth suppression of M. phaseolina and its chromogenic aberration in liquid culture. Genome mining of B. contaminans NZ using NaPDoS and antiSMASH revealed gene clusters that displayed 100% similarity for cytotoxic and antifungal substances, such as pyrrolnitrin. GC-MS analysis of B. contaminans NZ culture extracts revealed various bioactive compounds, including catechol; 9,10-dihydro-12'-hydroxy-2'-methyl-5'-(phenylmethyl)- ergotaman 3',6',18-trione; 2,3-dihydro-3,5- dihydroxy-6-methyl-4H-pyran-4-one; 1-(1,6-Dioxooctadecyl)- pyrrolidine; 9-Octadecenamide; and 2- methoxy- phenol. These compounds reportedly exhibit tyrosinase inhibitory, antifungal, and antibiotic activities. Using a more targeted approach, an RP-HPLC purified fraction was analyzed by LC-MS, confirming the existence of pyrrolnitrin in the B. contaminans NZ extract. Secondary metabolites, such as catechol and ergotaman, have been predicted to inhibit melanin synthesis in M. phaseolina. Thus, B. contaminans NZ appears to inhibit phytopathogens by apparently impairing melanin synthesis and other potential biochemical pathways, exhibiting considerable fungistatic activity.
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Affiliation(s)
- Nazia R. Zaman
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
| | - Umar F. Chowdhury
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
| | - Rifath N. Reza
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
| | - Farhana T. Chowdhury
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
| | - Mrinmoy Sarker
- NSU Genome Research Institute (NGRI), Department of Biochemistry and Microbiology, North South University, Dhaka, Bangladesh
| | - Muhammad M. Hossain
- NSU Genome Research Institute (NGRI), Department of Biochemistry and Microbiology, North South University, Dhaka, Bangladesh
| | - Md. Ahedul Akbor
- Institute of National Analytical Research and Service (INARS), Bangladesh Council of Scientific and Industrial Research (BCSIR), Dhaka, Bangladesh
| | - Al Amin
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
| | - Mohammad Riazul Islam
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
| | - Haseena Khan
- Molecular Biology Laboratory, Department of Biochemistry and Molecular Biology, Faculty Biological Sciences, University of Dhaka, Dhaka, Bangladesh
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Pimenta AI, Bernardes N, Alves MM, Mil-Homens D, Fialho AM. Burkholderia cenocepacia transcriptome during the early contacts with giant plasma membrane vesicles derived from live bronchial epithelial cells. Sci Rep 2021; 11:5624. [PMID: 33707642 PMCID: PMC7970998 DOI: 10.1038/s41598-021-85222-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 02/22/2021] [Indexed: 01/31/2023] Open
Abstract
Burkholderia cenocepacia is known for its capacity of adherence and interaction with the host, causing severe opportunistic lung infections in cystic fibrosis patients. In this work we produced Giant Plasma Membrane Vesicles (GPMVs) from a bronchial epithelial cell line and validated their use as a cell-like alternative to investigate the steps involved in the adhesion process of B. cenocepacia. RNA-sequencing was performed and the analysis of the B. cenocepacia K56-2 transcriptome after the first contacts with the surface of host cells allowed the recognition of genes implicated in bacterial adaptation and virulence-associated functions. The sensing of host membranes led to a transcriptional shift that caused a cascade of metabolic and physiological adaptations to the host specific environment. Many of the differentially expressed genes encode proteins related with central metabolic pathways, transport systems, cellular processes, and virulence traits. The understanding of the changes in gene expression that occur in the early steps of infection can uncover new proteins implicated in B. cenocepacia-host cell adhesion, against which new blocking agents could be designed to control the progression of the infectious process.
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Affiliation(s)
- Andreia I. Pimenta
- iBB-Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
| | - Nuno Bernardes
- iBB-Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
| | - Marta M. Alves
- grid.9983.b0000 0001 2181 4263CQE Instituto Superior Técnico, Departamento de Engenharia Química, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Dalila Mil-Homens
- iBB-Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
| | - Arsenio M. Fialho
- iBB-Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal ,grid.9983.b0000 0001 2181 4263Department of Bioengineering, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
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Pimenta AI, Mil‐Homens D, Fialho AM. Burkholderia cenocepacia-host cell contact controls the transcription activity of the trimeric autotransporter adhesin BCAM2418 gene. Microbiologyopen 2020; 9:e998. [PMID: 32097539 PMCID: PMC7142374 DOI: 10.1002/mbo3.998] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/02/2020] [Accepted: 01/04/2020] [Indexed: 12/11/2022] Open
Abstract
Cell-to-cell early contact between pathogens and their host cells is required for the establishment of many infections. Among various surface factors produced by bacteria that allow an organism to become established in a host, the class of adhesins is a primary determinant. Burkholderia cenocepacia adheres to the respiratory epithelium of cystic fibrosis patients and causes chronic inflammation and disease. Cell-to-cell contacts are promoted by various kinds of adhesins, including trimeric autotransporter adhesins (TAAs). We observed that among the 7 TAA genes found in the B. cenocepacia K56-2 genome, two of them (BCAM2418 and BCAS0236) express higher levels of mRNA following physical contact with host cells. Further analysis revealed that the B. cenocepacia K56-2 BCAM2418 gene shows an on-off switch after an initial colonization period, exhibits a strong expression dependent on the host cell type, and enhances its function on cell adhesion. Furthermore, our analysis revealed that adhesion to mucin-coated surfaces dramatically increases the expression levels of BCAM2418. Abrogation of mucin O-glycans turns BCAM2418 gene expression off and impairs bacterial adherence. Overall, our findings suggest that glycosylated extracellular components of host membrane might be a binding site for B. cenocepacia and a signal for the differential expression of the TAA gene BCAM2418.
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Affiliation(s)
- Andreia I. Pimenta
- iBB‐Institute for Bioengineering and BiosciencesInstituto Superior Técnico, University of LisbonLisbonPortugal
| | - Dalila Mil‐Homens
- iBB‐Institute for Bioengineering and BiosciencesInstituto Superior Técnico, University of LisbonLisbonPortugal
| | - Arsenio M. Fialho
- iBB‐Institute for Bioengineering and BiosciencesInstituto Superior Técnico, University of LisbonLisbonPortugal
- Department of BioengineeringInstituto Superior TécnicoUniversity of LisbonLisbonPortugal
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Ganesh PS, Vishnupriya S, Vadivelu J, Mariappan V, Vellasamy KM, Shankar EM. Intracellular survival and innate immune evasion of Burkholderia cepacia: Improved understanding of quorum sensing-controlled virulence factors, biofilm, and inhibitors. Microbiol Immunol 2020; 64:87-98. [PMID: 31769530 DOI: 10.1111/1348-0421.12762] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/18/2019] [Accepted: 11/21/2019] [Indexed: 12/25/2022]
Abstract
Burkholderia cepacia complex (Bcc) are opportunistic pathogens implicated with nosocomial infections, and high rates of morbidity and mortality, especially in individuals with cystic fibrosis (CF). B. cepacia are naturally resistant to different classes of antibiotics, and can subvert the host innate immune responses by producing quorum sensing (QS) controlled virulence factors and biofilms. It still remains a conundrum as to how exactly the bacterium survives the intracellular environment within the host cells of CF patients and immunocompromised individuals although the bacterium can invade human lung epithelial cells, neutrophils, and murine macrophages. The mechanisms associated with intracellular survival in the airway epithelial cells and the role of QS and virulence factors in B. cepacia infections in cystic fibrosis remain largely unclear. The current review focuses on understanding the role of QS-controlled virulence factors and biofilms, and provides additional impetus to understanding the potentials of QS-inhibitory strategies against B. cepacia.
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Affiliation(s)
- Pitchaipillai Sankar Ganesh
- Division of Infection Biology & Medical Microbiology, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
| | - Sivakumar Vishnupriya
- Division of Infection Biology & Medical Microbiology, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Vanitha Mariappan
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kumutha M Vellasamy
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Esaki M Shankar
- Division of Infection Biology & Medical Microbiology, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, India
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Ji Y, Bolhuis A, Watson ML. Staphylococcus aureus products subvert the Burkholderia cenocepacia-induced inflammatory response in airway epithelial cells. J Med Microbiol 2019; 68:1813-1822. [PMID: 31674896 DOI: 10.1099/jmm.0.001100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Introduction. Chronic pulmonary infection is associated with colonization with multiple micro-organisms but host-microbe and microbe-microbe interactions are poorly understood.Aim. This study aims to investigate the differences in host responses to mono- and co-infection with S. aureus and B. cenocepacia in human airway epithelial cells.Methodology. We assessed the effect of co-infection with B. cenocepacia and S. aureus on host signalling and inflammatory responses in the human airway epithelial cell line 16HBE, using ELISA and western blot analysis.Results. The results show that B. cenocepacia activates MAPK and NF-κB signalling pathways, subsequently eliciting robust interleukin (IL)-8 production. However, when airway epithelial cells were co-treated with live B. cenocepacia bacteria and S. aureus supernatants (conditioned medium), the pro-inflammatory response was attenuated. This anti-inflammatory effect was widely exhibited in the S. aureus isolates tested and was mediated via reduced MAPK and NF-κB signalling, but not via IL-1 receptor or tumour necrosis factor receptor modulation. The staphylococcal effectors were characterized as small, heat-stable, non-proteinaceous and not cell wall-related factors.Conclusion. This study demonstrates for the first time the host response in a S. aureus/B. cenocepacia co-infection model and provides insight into a staphylococcal immune evasion mechanism, as well as a therapeutic intervention for excessive inflammation.
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Affiliation(s)
- Yuan Ji
- Department of Pharmacy and Pharmacology, University of Bath, BA2 7AY, UK
| | - Albert Bolhuis
- Department of Pharmacy and Pharmacology, University of Bath, BA2 7AY, UK
| | - Malcolm L Watson
- Department of Pharmacy and Pharmacology, University of Bath, BA2 7AY, UK
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Wallner A, King E, Ngonkeu ELM, Moulin L, Béna G. Genomic analyses of Burkholderia cenocepacia reveal multiple species with differential host-adaptation to plants and humans. BMC Genomics 2019; 20:803. [PMID: 31684866 PMCID: PMC6829993 DOI: 10.1186/s12864-019-6186-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 10/15/2019] [Indexed: 12/17/2022] Open
Abstract
Background Burkholderia cenocepacia is a human opportunistic pathogen causing devastating symptoms in patients suffering from immunodeficiency and cystic fibrosis. Out of the 303 B. cenocepacia strains with available genomes, the large majority were isolated from a clinical context. However, several isolates originate from other environmental sources ranging from aerosols to plant endosphere. Plants can represent reservoirs for human infections as some pathogens can survive and sometimes proliferate in the rhizosphere. We therefore investigated if B. cenocepacia had the same potential. Results We selected genome sequences from 31 different strains, representative of the diversity of ecological niches of B. cenocepacia, and conducted comparative genomic analyses in the aim of finding specific niche or host-related genetic determinants. Phylogenetic analyses and whole genome average nucleotide identity suggest that strains, registered as B. cenocepacia, belong to at least two different species. Core-genome analyses show that the clade enriched in environmental isolates lacks multiple key virulence factors, which are conserved in the sister clade where most clinical isolates fall, including the highly virulent ET12 lineage. Similarly, several plant associated genes display an opposite distribution between the two clades. Finally, we suggest that B. cenocepacia underwent a host jump from plants/environment to animals, as supported by the phylogenetic analysis. We eventually propose a name for the new species that lacks several genetic traits involved in human virulence. Conclusion Regardless of the method used, our studies resulted in a disunited perspective of the B. cenocepacia species. Strains currently affiliated to this taxon belong to at least two distinct species, one having lost several determining animal virulence factors.
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Affiliation(s)
- Adrian Wallner
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France
| | - Eoghan King
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France
| | - Eddy L M Ngonkeu
- Institute of Agronomic Research for Development (IRAD), PO Box 2123, Yaoundé, Cameroon
| | - Lionel Moulin
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France
| | - Gilles Béna
- IRD, CIRAD, University of Montpellier, IPME; 911 avenue Agropolis, BP 64501, 34394, Montpellier, France.
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11
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Trifonova A, Strateva T. Stenotrophomonas maltophilia – a low-grade pathogen with numerous virulence factors. Infect Dis (Lond) 2018; 51:168-178. [DOI: 10.1080/23744235.2018.1531145] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Angelina Trifonova
- Laboratory of Microbiology, Department of Military Epidemiology and Hygiene, Military Medical Academy, Sofia, Bulgaria
| | - Tanya Strateva
- Department of Medical Microbiology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
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12
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Buroni S, Scoffone VC, Fumagalli M, Makarov V, Cagnone M, Trespidi G, De Rossi E, Forneris F, Riccardi G, Chiarelli LR. Investigating the Mechanism of Action of Diketopiperazines Inhibitors of the Burkholderia cenocepacia Quorum Sensing Synthase CepI: A Site-Directed Mutagenesis Study. Front Pharmacol 2018; 9:836. [PMID: 30108505 PMCID: PMC6079302 DOI: 10.3389/fphar.2018.00836] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/11/2018] [Indexed: 12/24/2022] Open
Abstract
Quorum sensing (QS) is a bacterial intercellular communication process which controls the production of major virulence factors, such as proteases, siderophores, and toxins, as well as biofilm formation. Since the inhibition of this pathway reduces bacterial virulence, QS is considered a valuable candidate drug target, particularly for the treatment of opportunistic infections, such as those caused by Burkholderia cenocepacia in cystic fibrosis patients. Diketopiperazine inhibitors of the acyl homoserine lactone synthase CepI have been recently described. These compounds are able to impair the ability of B. cenocepacia to produce proteases, siderophores, and to form biofilm, being also active in a Caenorhabditis elegans infection model. However, the precise mechanism of action of the compounds, as well as their effect on the cell metabolism, fundamental for candidate drug optimization, are still not completely defined. Here, we performed a proteomic analysis of B. cenocepacia cells treated with one of these inhibitors, and compared it with a cepI deleted strain. Our results demonstrate that the effects of the compound are similar to the deletion of cepI, clearly confirming that these molecules function as inhibitors of the acyl homoserine lactone synthase. Moreover, to deepen our knowledge about the binding mechanisms of the compound to CepI, we exploited previously published in silico structural insights about this enzyme structure and validated different candidate binding pockets on the enzyme surface using site-directed mutagenesis and biochemical analyses. Our experiments identified a region near the predicted S-adenosylmethionine binding site critically involved in interactions with the inhibitor. These results could be useful for future structure-based optimization of these CepI inhibitors.
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Affiliation(s)
- Silvia Buroni
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Viola C Scoffone
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Marco Fumagalli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Vadim Makarov
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | | | - Gabriele Trespidi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Edda De Rossi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Federico Forneris
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Giovanna Riccardi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Laurent R Chiarelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
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13
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Chaparro C, Keshavjee S. Lung transplantation for cystic fibrosis: an update. Expert Rev Respir Med 2016; 10:1269-1280. [DOI: 10.1080/17476348.2016.1261016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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14
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McClean S. Prospects for subunit vaccines: Technology advances resulting in efficacious antigens requires matching advances in early clinical trial investment. Hum Vaccin Immunother 2016; 12:3103-3106. [PMID: 27494532 DOI: 10.1080/21645515.2016.1216287] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
With the continued march of antimicrobial resistance, a renewed impetus for better vaccines has been heralded. Identification of potent subunit vaccines has been greatly facilitated by recent developments in reverse vaccinology and proteomics strategies. There are a range of antimicrobial resistant bacterial pathogens that could be targeted by potent vaccine antigens identified within the coming years. However, cost is a significant hurdle in progressing lead antigen candidates to clinical trials. In order for novel vaccine technologies to realize their clinical potential, there is a requirement to improve investment and incentives to expedite the development of vaccines that are apparently efficacious in preclinical trials.
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Affiliation(s)
- Siobhán McClean
- a Centre of Microbial Host Interactions , Institute of Technology Tallaght , Dublin , Ireland
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15
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Deng P, Wang X, Baird SM, Showmaker KC, Smith L, Peterson DG, Lu S. Comparative genome-wide analysis reveals that Burkholderia contaminans MS14 possesses multiple antimicrobial biosynthesis genes but not major genetic loci required for pathogenesis. Microbiologyopen 2016; 5:353-69. [PMID: 26769582 PMCID: PMC4905989 DOI: 10.1002/mbo3.333] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/22/2015] [Accepted: 12/03/2015] [Indexed: 11/13/2022] Open
Abstract
Burkholderia contaminans MS14 shows significant antimicrobial activities against plant and animal pathogenic fungi and bacteria. The antifungal agent occidiofungin produced by MS14 has great potential for development of biopesticides and pharmaceutical drugs. However, the use of Burkholderia species as biocontrol agent in agriculture is restricted due to the difficulties in distinguishing between plant growth-promoting bacteria and the pathogenic bacteria. The complete MS14 genome was sequenced and analyzed to find what beneficial and virulence-related genes it harbors. The phylogenetic relatedness of B. contaminans MS14 and other 17 Burkholderia species was also analyzed. To research MS14's potential virulence, the gene regions related to the antibiotic production, antibiotic resistance, and virulence were compared between MS14 and other Burkholderia genomes. The genome of B. contaminans MS14 was sequenced and annotated. The genomic analyses reveal the presence of multiple gene sets for antimicrobial biosynthesis, which contribute to its antimicrobial activities. BLAST results indicate that the MS14 genome harbors a large number of unique regions. MS14 is closely related to another plant growth-promoting Burkholderia strain B. lata 383 according to the average nucleotide identity data. Moreover, according to the phylogenetic analysis, plant growth-promoting species isolated from soils and mammalian pathogenic species are clustered together, respectively. MS14 has multiple antimicrobial activity-related genes identified from the genome, but it lacks key virulence-related gene loci found in the pathogenic strains. Additionally, plant growth-promoting Burkholderia species have one or more antimicrobial biosynthesis genes in their genomes as compared with nonplant growth-promoting soil-isolated Burkholderia species. On the other hand, pathogenic species harbor multiple virulence-associated gene loci that are not present in nonpathogenic Burkholderia species. The MS14 genome as well as Burkholderia species genome show considerable diversity. Multiple antimicrobial agent biosynthesis genes were identified in the genome of plant growth-promoting species of Burkholderia. In addition, by comparing to nonpathogenic Burkholderia species, pathogenic Burkholderia species have more characterized homologs of the gene loci known to contribute to pathogenicity and virulence to plant and animals.
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Affiliation(s)
- Peng Deng
- Departments of Biochemistry, Molecular BiologyEntomology and Plant PathologyMississippi State UniversityMississippi stateMississippi
| | - Xiaoqiang Wang
- Departments of Biochemistry, Molecular BiologyEntomology and Plant PathologyMississippi State UniversityMississippi stateMississippi
| | - Sonya M. Baird
- Departments of Biochemistry, Molecular BiologyEntomology and Plant PathologyMississippi State UniversityMississippi stateMississippi
| | - Kurt C. Showmaker
- Institute for GenomicsBiocomputing and BiotechnologyMississippi State UniversityMississippi stateMississippi
| | - Leif Smith
- Department of BiologyTexas A&M UniversityCollege StationTexas
| | - Daniel G. Peterson
- Institute for GenomicsBiocomputing and BiotechnologyMississippi State UniversityMississippi stateMississippi
| | - Shien Lu
- Departments of Biochemistry, Molecular BiologyEntomology and Plant PathologyMississippi State UniversityMississippi stateMississippi
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16
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David J, Bell RE, Clark GC. Mechanisms of Disease: Host-Pathogen Interactions between Burkholderia Species and Lung Epithelial Cells. Front Cell Infect Microbiol 2015; 5:80. [PMID: 26636042 PMCID: PMC4649042 DOI: 10.3389/fcimb.2015.00080] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/30/2015] [Indexed: 11/17/2022] Open
Abstract
Members of the Burkholderia species can cause a range of severe, often fatal, respiratory diseases. A variety of in vitro models of infection have been developed in an attempt to elucidate the mechanism by which Burkholderia spp. gain entry to and interact with the body. The majority of studies have tended to focus on the interaction of bacteria with phagocytic cells with a paucity of information available with regard to the lung epithelium. However, the lung epithelium is becoming more widely recognized as an important player in innate immunity and the early response to infections. Here we review the complex relationship between Burkholderia species and epithelial cells with an emphasis on the most pathogenic species, Burkholderia pseudomallei and Burkholderia mallei. The current gaps in knowledge in our understanding are highlighted along with the epithelial host-pathogen interactions that offer potential opportunities for therapeutic intervention.
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Affiliation(s)
- Jonathan David
- Microbiology, Biomedical Sciences, Defence Science and Technology Laboratory Salisbury, UK
| | - Rachel E Bell
- Microbiology, Biomedical Sciences, Defence Science and Technology Laboratory Salisbury, UK ; Division of Immunology, Infection and Inflammatory Disease, Centre for Molecular and Cellular Biology of Inflammation, King's College London London, UK
| | - Graeme C Clark
- Microbiology, Biomedical Sciences, Defence Science and Technology Laboratory Salisbury, UK
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17
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Shommu NS, Vogel HJ, Storey DG. Potential of metabolomics to reveal Burkholderia cepacia complex pathogenesis and antibiotic resistance. Front Microbiol 2015. [PMID: 26217312 PMCID: PMC4499752 DOI: 10.3389/fmicb.2015.00668] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The Burkholderia cepacia complex (Bcc) is a collection of closely related, genetically distinct, ecologically diverse species known to cause life-threatening infections in cystic fibrosis (CF) patients. By virtue of a flexible genomic structure and diverse metabolic activity, Bcc bacteria employ a wide array of virulence factors for pathogenesis in CF patients and have developed resistance to most of the commonly used antibiotics. However, the mechanism of pathogenesis and antibiotic resistance is still not fully understood. This mini review discusses the established and potential virulence determinants of Bcc and some of the contemporary strategies including transcriptomics and proteomics used to identify these traits. We also propose the application of metabolic profiling, a cost-effective modern-day approach to achieve new insights.
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Affiliation(s)
- Nusrat S Shommu
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary , Calgary, AB, Canada
| | - Hans J Vogel
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary , Calgary, AB, Canada
| | - Douglas G Storey
- Microbiology Research Group, Department of Biological Sciences, University of Calgary , Calgary, AB, Canada
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18
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Zlosnik JEA, Mori PY, To D, Leung J, Hird TJ, Speert DP. Swimming motility in a longitudinal collection of clinical isolates of Burkholderia cepacia complex bacteria from people with cystic fibrosis. PLoS One 2014; 9:e106428. [PMID: 25203161 PMCID: PMC4159263 DOI: 10.1371/journal.pone.0106428] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/29/2014] [Indexed: 12/13/2022] Open
Abstract
Chronic bacterial lung infections in cystic fibrosis (CF) are the leading cause of morbidity and mortality. While a range of bacteria are known to be capable of establishing residence in the CF lung, only a small number have a clearly established link to deteriorating clinical status. The two bacteria with the clearest roles in CF lung disease are Pseudomonas aeruginosa and bacteria belonging to the Burkholderia cepacia complex (BCC). A number of common adaptations by P. aeruginosa strains to chronic lung infection in CF have been well described. Typically, initial isolates of P. aeruginosa are nonmucoid and display a range of putative virulence determinants. Upon establishment of chronic infection, subsequent isolates ultimately show a reduction in putative virulence determinants, including swimming motility, along with an acquisition of the mucoid phenotype and increased levels of antimicrobial resistance. Infections by BCC are marked by an unpredictable, but typically worse, clinical outcome. However, in contrast to P. aeruginosa infections in CF, studies describing adaptive changes in BCC bacterial phenotype during chronic lung infections are far more limited. To further enhance our understanding of chronic lung infections by BCC bacteria in CF, we assessed the swimming motility phenotype in 551 isolates of BCC bacteria from cystic fibrosis (CF) lung infections between 1981 and 2007. These data suggest that swimming motility is not typically lost by BCC during chronic infection, unlike as seen in P. aeruginosa infections. Furthermore, while we observed a statistically significant link between mucoidy and motility, we did not detect any link between motility phenotype and clinical outcome. These studies highlight the need for further work to understand the adaptive changes of BCC bacteria during chronic infection in the CF lung.
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Affiliation(s)
- James E. A. Zlosnik
- Centre for Understanding and Preventing Infection in Children, Department of Pediatrics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
| | - Paul Y. Mori
- Centre for Understanding and Preventing Infection in Children, Department of Pediatrics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Derek To
- Centre for Understanding and Preventing Infection in Children, Department of Pediatrics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - James Leung
- Centre for Understanding and Preventing Infection in Children, Department of Pediatrics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Trevor J. Hird
- Centre for Understanding and Preventing Infection in Children, Department of Pediatrics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - David P. Speert
- Centre for Understanding and Preventing Infection in Children, Department of Pediatrics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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19
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Virulence genes in clinical and environmental Stenotrophomas maltophilia isolates: a genome sequencing and gene expression approach. Microb Pathog 2014; 67-68:20-30. [PMID: 24530922 DOI: 10.1016/j.micpath.2014.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 01/29/2014] [Accepted: 02/05/2014] [Indexed: 11/21/2022]
Abstract
The rate of nosocomial infections with the opportunistic pathogen Stenotrophomonas maltophilia has remarkably increased in the last decade. To determine S. maltophilia virulence genes, the complete genome sequences of two S. maltophilia isolates were compared. The clinical strain SKK35 was proved virulent in an amoeba host-pathogen model, and wastewater strain RA8 was determined as non-virulent in the amoeba model. The genome sequences of three additional S. maltophilia strains, K279a (clinical, non-virulent against amoeba), R511-3 and SKA14 (both environmental, non-virulent against amoeba) were taken into account as reference strains. We were able to show that all clinical and environmental S. maltophilia strains presented comparable distribution of so far identified potential virulence genes, regardless to their virulence potential against amoebae. Aside from that, strain SKK35 was found harboring a putative, strain specific pathogenicity island, encoding two proteins from the RTX (repeats-in-toxin) family. The actual expression of the RTX genes was verified in growth experiments in different culture media containing blood or blood components and in co-cultures with amoeba.
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20
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Denman CC, Brown AR. Mannitol promotes adherence of an outbreak strain of Burkholderia multivorans via an exopolysaccharide-independent mechanism that is associated with upregulation of newly identified fimbrial and afimbrial adhesins. MICROBIOLOGY-SGM 2013; 159:771-781. [PMID: 23378576 DOI: 10.1099/mic.0.064832-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia multivorans, a member of the Burkholderia cepacia complex (Bcc), is an important pathogen of the cystic fibrosis (CF) lung. Mannitol, approved as an inhaled osmolyte therapy for use in CF patients, promotes exopolysaccharide (EPS) production by the Bcc. In the present study, we investigated the role of mannitol-induced EPS in the adherence of B. multivorans. We report that mannitol promoted adherence of two representative B. multivorans strains. However, whilst this enhanced adherence was largely EPS-dependent in an environmental isolate, it was EPS-independent within a CF outbreak strain, suggesting strain-to-strain variation in adhesins. Genome sequencing of the outbreak strain enabled the identification of two distinct loci encoding putative fimbrial and afimbrial adhesins. The putative fimbriae-encoding locus was found to be widely distributed amongst clinical and environmental B. multivorans. In contrast, the locus encoding the putative afimbrial adhesin (of the filamentous haemagglutinin family, FHA) was restricted to clinical isolates. Both loci contributed to biofilm formation and mucin adherence. Furthermore, we report that mannitol promoted expression of both loci, and that the locus encoding the putative FHA-family adhesin is a key determinant of the enhanced adherence observed following growth in mannitol. Our studies provide the first characterization, to our knowledge, of B. multivorans adhesins, and in so doing highlight the strain-dependent role of EPS in the Bcc and the difficulties in assigning phenotypic traits to Bcc EPS due to the wider response to mannitol. Our observations also highlight the need to monitor the microbiological effects of inhaled mannitol therapy in Bcc-infected CF patients.
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Affiliation(s)
- Carmen C Denman
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Alan R Brown
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
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21
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Inhülsen S, Aguilar C, Schmid N, Suppiger A, Riedel K, Eberl L. Identification of functions linking quorum sensing with biofilm formation in Burkholderia cenocepacia H111. Microbiologyopen 2012; 1:225-42. [PMID: 22950027 PMCID: PMC3426421 DOI: 10.1002/mbo3.24] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 03/29/2012] [Accepted: 04/03/2012] [Indexed: 01/08/2023] Open
Abstract
Burkholderia cenocepacia has emerged as an important pathogen for patients suffering from cystic fibrosis (CF). Previous work has shown that this organism employs the CepIR quorum-sensing (QS) system to control the expression of virulence factors as well as the formation of biofilms. To date, however, very little is known about the QS-regulated virulence factors and virtually nothing about the factors that link QS and biofilm formation. Here, we have employed a combined transcriptomic and proteomic approach to precisely define the QS regulon in our model strain B. cenocepacia H111, a CF isolate. Among the identified CepR-activated loci, three were analyzed in better detail for their roles in biofilm development: (i) a gene cluster coding for the BclACB lectins, (ii) the large surface protein BapA, and (iii) a type I pilus. The analysis of defined mutants revealed that BapA plays a major role in biofilm formation on abiotic surfaces while inactivation of the type I pilus showed little effect both in a static microtitre dish-based biofilm assay and in flow-through cells. Inactivation of the bclACB lectin genes resulted in biofilms containing hollow microcolonies, suggesting that the lectins are important for biofilm structural development.
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Affiliation(s)
- Silja Inhülsen
- Department of Microbiology, Institute of Plant Biology, University of ZurichZollikerstrasse, 107, 8008 Zurich, Switzerland
| | - Claudio Aguilar
- Department of Microbiology, Institute of Plant Biology, University of ZurichZollikerstrasse, 107, 8008 Zurich, Switzerland
| | - Nadine Schmid
- Department of Microbiology, Institute of Plant Biology, University of ZurichZollikerstrasse, 107, 8008 Zurich, Switzerland
| | - Angela Suppiger
- Department of Microbiology, Institute of Plant Biology, University of ZurichZollikerstrasse, 107, 8008 Zurich, Switzerland
| | - Kathrin Riedel
- Institute of Microbiology, Ernst-Moritz-Arndt University of GreifswaldFriedrich-Ludwig-Jahn-Strasse 15, D-17487, Greifswald,, Germany
| | - Leo Eberl
- Department of Microbiology, Institute of Plant Biology, University of ZurichZollikerstrasse, 107, 8008 Zurich, Switzerland
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22
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Ganesan S, Sajjan US. Host evasion by Burkholderia cenocepacia. Front Cell Infect Microbiol 2012; 1:25. [PMID: 22919590 PMCID: PMC3417383 DOI: 10.3389/fcimb.2011.00025] [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: 09/16/2011] [Accepted: 12/22/2011] [Indexed: 11/13/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic respiratory pathogen of individuals with cystic fibrosis (CF). Some strains of B. cenocepacia are highly transmissible and resistant to almost all antibiotics. Approximately one-third of B. cenocepacia infected CF patients go on to develop fatal "cepacia syndrome." During the last two decades, substantial progress has been made with regards to evasion of host innate defense mechanisms by B. cenocepacia. Almost all strains of B. cenocepacia have the capacity to survive and replicate intracellularly in both airway epithelial cells and macrophages, which are primary sentinels of the lung and play a pivotal role in clearance of infecting bacteria. Those strains of B. cenocepacia, which express both cable pili and the associated 22 kDa adhesin are also capable of transmigrating across airway epithelium and persist in mouse models of infection. In this review, we will discuss how this type of interaction between B. cenocepacia and host may lead to persistence of bacteria as well as lung inflammation in CF patients.
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Affiliation(s)
- Shyamala Ganesan
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI, USA
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23
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Genomic expression analysis reveals strategies of Burkholderia cenocepacia to adapt to cystic fibrosis patients' airways and antimicrobial therapy. PLoS One 2011; 6:e28831. [PMID: 22216120 PMCID: PMC3244429 DOI: 10.1371/journal.pone.0028831] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 11/15/2011] [Indexed: 12/20/2022] Open
Abstract
Pulmonary colonization of cystic fibrosis (CF) patients with Burkholderia cenocepacia or other bacteria of the Burkholderia cepacia complex (Bcc) is associated with worse prognosis and increased risk of death. During colonization, the bacteria may evolve under the stressing selection pressures exerted in the CF lung, in particular, those resulting from challenges of the host immune defenses, antimicrobial therapy, nutrient availability and oxygen limitation. Understanding the adaptive mechanisms that promote successful colonization and long-term survival of B. cenocepacia in the CF lung is essential for an improved therapeutic outcome of chronic infections. To get mechanistic insights into these adaptive strategies a transcriptomic analysis, based on DNA microarrays, was explored in this study. The genomic expression levels in two clonal variants isolated during long-term colonization of a CF patient who died from the cepacia syndrome were compared. One of the isolates examined, IST439, is the first B. cenocepacia isolate retrieved from the patient and the other isolate, IST4113, was obtained three years later and is more resistant to different classes of antimicrobials. Approximately 1000 genes were found to be differently expressed in the two clonal variants reflecting a marked reprogramming of genomic expression. The up-regulated genes in IST4113 include those involved in translation, iron uptake (in particular, in ornibactin biosynthesis), efflux of drugs and in adhesion to epithelial lung tissue and to mucin. Alterations related with adaptation to the nutritional environment of the CF lung and to an oxygen-limited environment are also suggested to be a key feature of transcriptional reprogramming occurring during long-term colonization, antibiotic therapy and the progression of the disease.
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24
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Molecular approaches to pathogenesis study of Burkholderia cenocepacia, an important cystic fibrosis opportunistic bacterium. Appl Microbiol Biotechnol 2011; 92:887-95. [PMID: 21997606 DOI: 10.1007/s00253-011-3616-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 09/08/2011] [Accepted: 09/28/2011] [Indexed: 10/15/2022]
Abstract
Burkholderia cenocepacia is a Gram-negative opportunistic pathogen belonging to the Burkholderia cepacia complex (Bcc). It is spread in a wide range of ecological niches, and in cystic fibrosis patients, it is responsible for serious infections. Its eradication is very difficult due to the high level of intrinsic resistance to clinically relevant antibiotics. One of the main resistance mechanisms in clinical isolates is represented by efflux systems that are able to extrude a variety of molecules, such as antibiotics, out of the cell. Resistance-Nodulation-Cell Division (RND) efflux pumps are known to be mediators of multidrug resistance in Gram-negative bacteria. Since now, the significance of the RND efflux systems in B. cenocepacia has been partially determined. However, the analysis of the completely sequenced genome of B. cenocepacia J2315 allowed the identification of 16 operons coding for these transporters. We focused our attention on the role of these pumps through the construction of several deletion mutants. Since manipulating B. cenocepacia J2315 genome is difficult, we used a peculiar inactivation system, which enables different deletions in the same strain. The characterization of our mutants through transcriptome and phenotype microarray analysis suggested that RND efflux pumps can be involved not only in drug resistance but also in pathways important for the pathogenesis of this microorganism. The aim of this review is an updated overview on host-pathogen interactions and drug resistance, particularly focused on RND-mediated efflux mechanisms, highlighting the importance of molecular techniques in the study of B. cenocepacia.
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25
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Goldberg JB, Ganesan S, Comstock AT, Zhao Y, Sajjan US. Cable pili and the associated 22 kDa adhesin contribute to Burkholderia cenocepacia persistence in vivo. PLoS One 2011; 6:e22435. [PMID: 21811611 PMCID: PMC3141045 DOI: 10.1371/journal.pone.0022435] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 06/27/2011] [Indexed: 01/02/2023] Open
Abstract
Background Infection by Burkholderia cenocepacia in cystic fibrosis (CF) patients is associated with poor clinical prognosis. Previously, we demonstrated that one of the highly transmissible strains, BC7, expresses cable pili and the associated 22 kDa adhesin, both of which contribute to BC7 binding to airway epithelial cells. However, the contribution of these factors to induce inflammation and bacterial persistence in vivo is not known. Methodology/Principal Findings Wild-type BC7 stimulated higher IL-8 responses than the BC7 cbl and BC7 adhA mutants in both CF and normal bronchial epithelial cells. To determine the role of cable pili and the associated adhesin, we characterized a mouse model of B. cenocepacia, where BC7 are suspended in Pseudomonas aeruginosa alginate. C57BL/6 mice were infected intratracheally with wild-type BC7 suspended in either alginate or PBS and were monitored for lung bacterial load and inflammation. Mice infected with BC7 suspended in PBS completely cleared the bacteria by 3 days and resolved the inflammation. In contrast, mice infected with BC7 suspended in alginate showed persistence of bacteria and moderate lung inflammation up to 5 days post-infection. Using this model, mice infected with the BC7 cbl and BC7 adhA mutants showed lower bacterial loads and mild inflammation compared to mice infected with wild-type BC7. Complementation of the BC7 cblS mutation in trans restored the capacity of this strain to persist in vivo. Immunolocalization of bacteria revealed wild-type BC7 in both airway lumen and alveoli, while the BC7 cbl and BC7 adhA mutants were found mainly in airway lumen and peribronchiolar region. Conclusions and Significance B. cenocepacia suspended in alginate can be used to determine the capacity of bacteria to persist and cause lung inflammation in normal mice. Both cable pili and adhesin contribute to BC7-stimulated IL-8 response in vitro, and BC7 persistence and resultant inflammation in vivo.
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Affiliation(s)
- Joanna B. Goldberg
- Department of Microbiology, University of Virginia Health System, Charlottesville, Virginia, United States of America
| | - Shyamala Ganesan
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Adam T. Comstock
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Ying Zhao
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Uma S. Sajjan
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Rosenblueth M, Martinez-Romero JC, Reyes-Prieto M, Rogel MA, Martinez-Romero E. Environmental mycobacteria: a threat to human health? DNA Cell Biol 2011; 30:633-40. [PMID: 21595554 DOI: 10.1089/dna.2011.1231] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In many cases, bacterial pathogens are close relatives to nonpathogens. Pathogens seem to be limited lineages within nonpathogenic bacteria. Nonpathogenic isolates are generally more diverse and widespread in the environment and it is generally considered that environmental bacteria do not pose a risk to human health as clinical isolates do; this may not be the case with mycobacteria, but environmental mycobacteria have not been well studied. It is documented that several environmental mycobacteria constitute a source for human infections. Diverse mycobacterial environmental isolates are rarely involved in human disease. Environmental mycobacteria may have a role in degradation of different compounds. Environmental mycobacteria have had a long interaction with humans, maybe as long as the human species, and may have contributed to human evolution.
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Affiliation(s)
- Mónica Rosenblueth
- Centro de Ciencias Genomicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos, Mexico
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Behrends V, Bundy JG, Williams HD. Differences in strategies to combat osmotic stress in Burkholderia cenocepacia elucidated by NMR-based metabolic profiling. Lett Appl Microbiol 2011; 52:619-25. [PMID: 21446999 DOI: 10.1111/j.1472-765x.2011.03050.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS To investigate mechanisms of osmotic tolerance in Burkholderia cenocepacia, a member of the B. cepacia complex (Bcc) of closely related strains, which is of clinical as well as environmental importance. METHODS AND RESULTS We employed NMR-based metabolic profiling (metabolomics) to elucidate the metabolic consequences of high osmotic stress for five isolates of B. cenocepacia. The strains differed significantly in their levels of osmotic stress tolerance, and we identified three different sets of metabolic responses with the strains least impacted by osmotic stress exhibiting higher levels of the osmo-protective metabolites glycine-betaine and/or trehalose. Strains either increased concentrations or had constitutively high levels of these metabolites. CONCLUSIONS Even within the small set of B. cenocepacia isolates, there was a surprising degree of variability in the metabolic responses to osmotic stress. SIGNIFICANCE AND IMPACT OF THE STUDY The metabolic responses, and hence osmotic stress tolerance, vary between different B. cenocepacia isolates. This study provides a first look into the potentially highly diverse physiology of closely related strains of one species of the Bcc and illustrates that physiological or clinically relevant phenotypes are unlikely to be inferable from genetic relatedness within this species group.
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Affiliation(s)
- V Behrends
- Biomolecular Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, UK.
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Drevinek P, Mahenthiralingam E. Burkholderia cenocepacia in cystic fibrosis: epidemiology and molecular mechanisms of virulence. Clin Microbiol Infect 2011; 16:821-30. [PMID: 20880411 DOI: 10.1111/j.1469-0691.2010.03237.x] [Citation(s) in RCA: 309] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Burkholderia cepacia complex (Bcc) bacteria have gained notoriety as pathogens in cystic fibrosis (CF) because they are difficult to identify and treat, and also have the ability to spread between CF individuals. Of the 17 formally named species within the complex, Burkholderia multivorans and Burkholderia cenocepacia dominate in CF. Multilocus sequence typing has proven to be a very useful tool for tracing the global epidemiology of Bcc bacteria and has shown that B. cenocepacia strains with high transmissibility, such as the ET-12 strain (ST-28) and the Czech strain (ST-32), have spread epidemically within CF populations in Canada and Europe. The majority of research on the molecular pathogenesis of Bcc bacteria has focused on the B. cenocepacia ET-12 epidemic lineage, with gene mutation, genome sequence analysis and, most recently, global gene expression studies shedding considerable light on the virulence and antimicrobial resistance of this pathogen. These studies demonstrate that the ability of B. cenocepacia to acquire foreign DNA (genomic islands, insertion sequences and other mobile elements), regulate gene expression via quorum sensing, compete for iron during infection, and mediate antimicrobial resistance and inflammation via its membrane and surface polysaccharides are key features that underpin the virulence of different strains. With the wealth of molecular knowledge acquired in the last decade on B. cenocepacia strains, we are now in a much better position to develop strategies for the treatment of pathogenic colonization with Bcc and to answer key questions on pathogenesis concerning, for example, the factors that trigger the rapid clinical decline in CF patients.
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Affiliation(s)
- P Drevinek
- Paediatric Department, 2nd Medical School, Charles University, Prague, Czech Republic.
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Molecular mechanisms of chlorhexidine tolerance in Burkholderia cenocepacia biofilms. Antimicrob Agents Chemother 2011; 55:1912-9. [PMID: 21357299 DOI: 10.1128/aac.01571-10] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The high tolerance of biofilm-grown Burkholderia cepacia complex bacteria against antimicrobial agents presents considerable problems for the treatment of infected cystic fibrosis patients and the implementation of infection control guidelines. In the present study, we analyzed the tolerance of planktonic and sessile Burkholderia cenocepacia J2315 cultures and examined the transcriptional response of sessile cells to treatment with chlorhexidine. At low (0.0005%) and high (0.05%) concentrations, chlorhexidine had a similar effect on both populations, but at intermediate concentrations (0.015%) the antimicrobial activity was more pronounced in planktonic cultures. The exposure of sessile cells to chlorhexidine resulted in an upregulation of the transcription of 469 (6.56%) and the downregulation of 257 (3.59%) protein-coding genes. A major group of upregulated genes in the treated biofilms encoded membrane-related and regulatory proteins. In addition, several genes coding for drug resistance determinants also were upregulated. The phenotypic analysis of RND (resistance-nodulation-division) efflux pump mutants suggests the presence of lifestyle-specific chlorhexidine tolerance mechanisms; efflux system RND-4 (BCAL2820-BCAL2822) was more responsible for chlorhexidine tolerance in planktonic cells, while other systems (RND-3 [BCAL1672-BCAL1676] and RND-9 [BCAM1945-BCAM1947]) were linked to resistance in sessile cells. After sessile cell exposure, multiple genes encoding chemotaxis and motility-related proteins were upregulated in concert with the downregulation of an adhesin-encoding gene (BCAM2143), suggesting that sessile cells tried to escape the biofilm. We also observed the differential expression of 19 genes carrying putative small RNA molecules, indicating a novel role for these regulatory elements in chlorhexidine tolerance.
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Invasion of Burkholderia cepacia complex isolates into lung epithelial cells involves glycolipid receptors. Microb Pathog 2010; 49:381-7. [DOI: 10.1016/j.micpath.2010.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 07/14/2010] [Accepted: 08/16/2010] [Indexed: 01/20/2023]
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Burkholderia cepacia Complex: Emerging Multihost Pathogens Equipped with a Wide Range of Virulence Factors and Determinants. Int J Microbiol 2010; 2011. [PMID: 20811541 PMCID: PMC2929507 DOI: 10.1155/2011/607575] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 06/02/2010] [Indexed: 12/04/2022] Open
Abstract
The Burkholderia cepacia complex (Bcc) comprises at least 17 closely-related species of the β-proteobacteria subdivision, widely distributed in natural and man-made inhabitats. Bcc bacteria are endowed with an extraordinary metabolic diversity and emerged in the 1980s as life-threatening and difficult-to-treat pathogens among patients suffering from cystic fibrosis. More recently, these bacteria became recognized as a threat to hospitalized patients suffering from other diseases, in particular oncological patients. In the present paper, we review these and other traits of Bcc bacteria, as well as some of the strategies used to identify and validate the virulence factors and determinants used by these bacteria. The identification and characterization of these virulence factors is expected to lead to the design of novel therapeutic strategies to fight the infections caused by these emergent multidrug resistant human pathogens.
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Ammendolia MG, Bertuccini L, Iosi F, Minelli F, Berlutti F, Valenti P, Superti F. Bovine lactoferrin interacts with cable pili of Burkholderia cenocepacia. Biometals 2010; 23:531-42. [DOI: 10.1007/s10534-010-9333-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 03/25/2010] [Indexed: 12/01/2022]
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Saldías MS, Valvano MA. Interactions of Burkholderia cenocepacia and other Burkholderia cepacia complex bacteria with epithelial and phagocytic cells. Microbiology (Reading) 2009; 155:2809-2817. [DOI: 10.1099/mic.0.031344-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Burkholderia cenocepacia is a member of the B. cepacia complex (Bcc), a group of opportunistic bacteria that infect the airways of patients with cystic fibrosis (CF) and are extraordinarily resistant to almost all clinically useful antibiotics. Infections in CF patients with Bcc bacteria generally lead to a more rapid decline in lung function, and in some cases to the ‘cepacia syndrome’, a virtually deadly exacerbation of the lung infection with systemic manifestations. These characteristics of Bcc bacteria contribute to higher morbidity and mortality in infected CF patients. In the last 10 years considerable progress has been made in understanding the interactions between Bcc bacteria and mammalian host cells. Bcc isolates can survive either intracellularly within eukaryotic cells or extracellularly in host tissues. They survive within phagocytes and respiratory epithelial cells, and they have the ability to breach the respiratory epithelium layer. Survival and persistence of Bcc bacteria within host cells and tissues are believed to play a key role in pulmonary infection and to contribute to the persistent inflammation observed in patients with CF. This review summarizes recent findings concerning the interaction between Bcc bacteria and epithelial and phagocytic cells.
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Affiliation(s)
- M. Soledad Saldías
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Miguel A. Valvano
- Department of Medicine, University of Western Ontario, London, ON N6A 5C1, Canada
- Infectious Diseases Research Group, Siebens-Drake Research Institute, Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1, Canada
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Strains of Burkholderia cenocepacia genomovar IIIA possessing the cblA gene that are distinct from ET12. Diagn Microbiol Infect Dis 2009; 64:94-7. [DOI: 10.1016/j.diagmicrobio.2009.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 01/07/2009] [Accepted: 01/20/2009] [Indexed: 11/20/2022]
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McClean S, Callaghan M. Burkholderia cepacia complex: epithelial cell–pathogen confrontations and potential for therapeutic intervention. J Med Microbiol 2009; 58:1-12. [DOI: 10.1099/jmm.0.47788-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Burkholderia cepaciacomplex (Bcc) is an important and virulent pathogen in cystic fibrosis patients. The interactions between this pathogen and the host lung epithelium are being widely investigated but remain to be elucidated. The complex is very versatile and its interactions with the lung epithelial cells are many and varied. The first steps in the interaction are penetration of the mucosal blanket and subsequent adherence to the epithelial cell surface. A range of epithelial receptors have been reported to bind to Bcc. The next step in pathogenesis is the invasion of the lung epithelial cell and also translocation across the epithelium to the serosal side. Furthermore, pathogenesis is mediated by a range of virulence factors that elicit their effects on the epithelial cells. This review outlines these interactions and examines the therapeutic implications of understanding the mechanisms of pathogenesis of this difficult, antibiotic-resistant, opportunistic pathogen.
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Affiliation(s)
- Siobhán McClean
- Centre of Microbial Host Interactions, Institute of Technology Tallaght Dublin, Dublin 24, Ireland
| | - Máire Callaghan
- Centre of Microbial Host Interactions, Institute of Technology Tallaght Dublin, Dublin 24, Ireland
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The genome of Burkholderia cenocepacia J2315, an epidemic pathogen of cystic fibrosis patients. J Bacteriol 2008; 191:261-77. [PMID: 18931103 PMCID: PMC2612433 DOI: 10.1128/jb.01230-08] [Citation(s) in RCA: 283] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Bacterial infections of the lungs of cystic fibrosis (CF) patients cause major complications in the treatment of this common genetic disease. Burkholderia cenocepacia infection is particularly problematic since this organism has high levels of antibiotic resistance, making it difficult to eradicate; the resulting chronic infections are associated with severe declines in lung function and increased mortality rates. B. cenocepacia strain J2315 was isolated from a CF patient and is a member of the epidemic ET12 lineage that originated in Canada or the United Kingdom and spread to Europe. The 8.06-Mb genome of this highly transmissible pathogen comprises three circular chromosomes and a plasmid and encodes a broad array of functions typical of this metabolically versatile genus, as well as numerous virulence and drug resistance functions. Although B. cenocepacia strains can be isolated from soil and can be pathogenic to both plants and man, J2315 is representative of a lineage of B. cenocepacia rarely isolated from the environment and which spreads between CF patients. Comparative analysis revealed that ca. 21% of the genome is unique in comparison to other strains of B. cenocepacia, highlighting the genomic plasticity of this species. Pseudogenes in virulence determinants suggest that the pathogenic response of J2315 may have been recently selected to promote persistence in the CF lung. The J2315 genome contains evidence that its unique and highly adapted genetic content has played a significant role in its success as an epidemic CF pathogen.
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The complete genome, comparative and functional analysis of Stenotrophomonas maltophilia reveals an organism heavily shielded by drug resistance determinants. Genome Biol 2008; 9:R74. [PMID: 18419807 PMCID: PMC2643945 DOI: 10.1186/gb-2008-9-4-r74] [Citation(s) in RCA: 394] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 03/13/2008] [Accepted: 04/17/2008] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Stenotrophomonas maltophilia is a nosocomial opportunistic pathogen of the Xanthomonadaceae. The organism has been isolated from both clinical and soil environments in addition to the sputum of cystic fibrosis patients and the immunocompromised. Whilst relatively distant phylogenetically, the closest sequenced relatives of S. maltophilia are the plant pathogenic xanthomonads. RESULTS The genome of the bacteremia-associated isolate S. maltophilia K279a is 4,851,126 bp and of high G+C content. The sequence reveals an organism with a remarkable capacity for drug and heavy metal resistance. In addition to a number of genes conferring resistance to antimicrobial drugs of different classes via alternative mechanisms, nine resistance-nodulation-division (RND)-type putative antimicrobial efflux systems are present. Functional genomic analysis confirms a role in drug resistance for several of the novel RND efflux pumps. S. maltophilia possesses potentially mobile regions of DNA and encodes a number of pili and fimbriae likely to be involved in adhesion and biofilm formation that may also contribute to increased antimicrobial drug resistance. CONCLUSION The panoply of antimicrobial drug resistance genes and mobile genetic elements found suggests that the organism can act as a reservoir of antimicrobial drug resistance determinants in a clinical environment, which is an issue of considerable concern.
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Coordinate regulation of Salmonella pathogenicity island 1 (SPI1) and SPI4 in Salmonella enterica serovar Typhimurium. Infect Immun 2007; 76:1024-35. [PMID: 18160484 DOI: 10.1128/iai.01224-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Salmonella enterica serovar Typhimurium harbors five pathogenicity islands (SPI) required for infection in vertebrate hosts. Although the role of SPI1 in promoting epithelial invasion and proinflammatory cell death has been amply documented, SPI4 has only more recently been implicated in Salmonella virulence. SPI4 is a 24-kb pathogenicity island containing six open reading frames, siiA to siiF. Secretion of the 595-kDa SiiE protein requires a type I secretory system encoded by siiC, siiD, and siiF. An operon polarity suppressor (ops) sequence within the 5' untranslated region upstream of siiA is required for optimal SPI4 expression and predicted to bind the antiterminator RfaH. SiiE concentrations are decreased in a SPI1 mutant strain, suggesting that SPI1 and SPI4 may have common regulatory inputs. SPI1 gene expression is positively regulated by the transcriptional activators HilA, HilC, and HilD, encoded within SPI1, and negatively regulated by the regulators HilE and PhoP. Here, we show that mutations in hilA, hilC, or hilD similarly reduce expression of siiE, and mutations in hilE or phoP enhance siiE expression. Individual overexpression of HilA, HilC, or HilD in the absence of SPI1 cannot activate siiE expression, suggesting that these transcriptional regulators act in concert or in combination with additional SPI1-encoded regulatory loci to activate SPI4. HilA is no longer required for siiE expression in an hns mutant strain, suggesting that HilA promotes SPI4 expression by antagonizing the global transcriptional silencer H-NS. Coordinate regulation suggests that SPI1 and SPI4 play complementary roles in the interaction of S. enterica serovar Typhimurium with the host intestinal mucosa.
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Sousa SA, Ulrich M, Bragonzi A, Burke M, Worlitzsch D, Leitão JH, Meisner C, Eberl L, Sá-Correia I, Döring G. Virulence of Burkholderia cepacia complex strains in gp91phox-/- mice. Cell Microbiol 2007; 9:2817-25. [PMID: 17627623 DOI: 10.1111/j.1462-5822.2007.00998.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In cystic fibrosis (CF), infection with Burkholderia cepacia complex (Bcc) strains may cause long-term asymptomatic airway colonization, or severe lung infection leading to rapid pulmonary decline. To assess the virulence of Bcc strains, we established a lung infection model in mice with a null allele of the gene involved in X-linked chronic granulomatous disease (CGD). CGD mice, challenged intratracheally with 10(3) cells of the epidemic Burkholderia cenocepacia strain J2315, died within 3 days from sepsis after bacteria had multiplied to 3.3 x 10(8) cells. Infected mice developed neutrophil-dominated lung abscesses. Other B. cenocepacia strains and a B. cepacia strain were less virulent and one B. multivorans and one B. vietnamensis CF isolate were both avirulent. Bcc mutants, defective in exopolysaccharide synthesis or quorum sensing revealed diminished or no abscess formation and mortality. Immunofluorescence staining of Bcc-infected murine and CF lung tissues revealed colocalization of Bcc and neutrophils, suggesting Bcc persistence within neutrophils in CGD and CF. In vitro, Bcc cells were rapidly killed during aerobic neutrophil phagocytosis; however, the pathogens survived in neutrophils with blocked nicotinamide adenine dinucleotide phosphate oxidase activity and under anaerobic conditions. We conclude that the Bcc infection model in CGD mice is well suited for the assessment of Bcc virulence.
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Affiliation(s)
- Silvia A Sousa
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Wilhelmstrasse 31, 72074 Tübingen, Germany
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Cheung KJ, Li G, Urban TA, Goldberg JB, Griffith A, Lu F, Burns JL. Pilus-mediated epithelial cell death in response to infection with Burkholderia cenocepacia. Microbes Infect 2007; 9:829-37. [PMID: 17537663 DOI: 10.1016/j.micinf.2007.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2006] [Revised: 01/09/2007] [Accepted: 03/01/2007] [Indexed: 11/20/2022]
Abstract
Burkholderia cenocepacia is an opportunistic pathogen that can cause serious infections in cystic fibrosis (CF) patients. The ET12 lineage appears particularly virulent in CF; however, its pathogenesis is poorly understood and may be associated with host response. To help characterize this response, the ability of B. cenocepacia to induce cytotoxicity and apoptosis in an epithelial cell model was examined. Upon infection with B. cenocepacia strain K56-2, A549 human lung epithelial cells underwent significant cell death; propidium iodine staining and DNA fragmentation assays suggested apoptosis. Initiation of cell death was independent of the type III secretion system, biofilm formation, and secreted bacterial cytotoxins. However, the frequency of cell death was lower in cells infected with a non-piliated mutant, K56-2 cblA::Tp. Furthermore, purified cbl pili were found to directly induce cytotoxicity in A549 cells and activate caspase-9, -8, -7, and -3, the major cysteine proteinases involved in apoptosis. It appears that B. cenocepacia cbl pili, which are a distinctive feature of the ET12 lineage, act as an initiator of cytotoxicity and apoptosis. Understanding the role of cbl pili in the pathogenesis of B. cenocepacia infections offers the potential for decreasing the virulence of these potentially life-threatening organisms in CF patients.
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Affiliation(s)
- K-John Cheung
- Division of Infectious Diseases, Immunology and Rheumatology, Children's Hospital and Regional Medical Center, 307 Westlake Avenue N., Seattle, WA 98109, USA
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Sajjan US, Yang JH, Hershenson MB, LiPuma JJ. Intracellular trafficking and replication of Burkholderia cenocepacia in human cystic fibrosis airway epithelial cells. Cell Microbiol 2006; 8:1456-66. [PMID: 16922864 DOI: 10.1111/j.1462-5822.2006.00724.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigated the trafficking of Burkholderia cenocepacia, an opportunistic respiratory pathogen of persons with cystic fibrosis (CF), in immortalized CF airway epithelial cells in vitro. Our results indicate that bacteria enter cells in a process involving actin rearrangement. Whereas both live and heat-killed bacteria reside transiently in early endosomes, only live bacteria escape from late endosomes to colocalize in vesicles positive for lysosomal membrane marker LAMP1, endoplasmic reticulum (ER) membrane marker calnexin, and autophagosome marker monodansylcadavarine (MDC). Twenty-four hours after infection, microcolonies of live bacteria were observed in the perinuclear area colocalizing with calnexin. In contrast, after ingestion, dead bacteria colocalized with late endosome marker Rab7, and lysosome markers LAMP1 and cathepsin D, but not with calnexin or MDC. Six to eight hours after ingestion of dead bacteria, degraded bacterial particles were observed in the cytoplasm and in vesicles positive for cathepsin D. These results indicate that live B. cenocepacia gain entry into human CF airway cells by endocytosis, escape from late endosomes to enter autophagosomes that fail to fuse with mature lysosomes, and undergo replication in the ER. This survival and replication strategy may contribute to the capacity of B. cenocepacia to persist in the lungs of infected CF patients.
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Affiliation(s)
- Umadevi S Sajjan
- Department of Pediatrics and Communicable Disease, University of Michigan Medical School, Ann Arbor, 48109, USA
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