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Huq M, Wahid SUH, Istivan T. Biofilm Formation in Campylobacter concisus: The Role of the luxS Gene. Microorganisms 2023; 12:46. [PMID: 38257873 PMCID: PMC10820981 DOI: 10.3390/microorganisms12010046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/24/2024] Open
Abstract
Campylobacter concisus is a bacterium that inhabits human oral cavities and is an emerging intestinal tract pathogen known to be a biofilm producer and one of the bacterial species found in dental plaque. In this study, biofilms of oral and intestinal C. concisus isolates were phenotypically characterized. The role of the luxS gene, which is linked to the regulation of biofilm formation in other pathogens, was assessed in relation to the pathogenic potential of this bacterium. Biofilm formation capacity was assessed using phenotypic assays. Oral strains were shown to be the highest producers. A luxS mutant was created by inserting a kanamycin cassette within the luxS gene of the highest biofilm-forming isolate. The loss of the polar flagellum was observed with scanning and transmission electron microscopy (SEM and TEM). Furthermore, the luxS mutant exhibited a significant reduction (p < 0.05) in biofilm formation, motility, and its expression of flaB, in addition to the capability to invade intestinal epithelial cells, compared to the parental strain. The study concluded that C. concisus oral isolates are significantly higher biofilm producers than the intestinal isolates and that LuxS plays a role in biofilm formation, invasion, and motility in this bacterium.
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Affiliation(s)
- Mohsina Huq
- School of Science, STEM College, RMIT University, Bundoora, Melbourne, VIC 3083, Australia
- Department of Medical Laboratories, College of Applied Medical Sciences, Qassim University, Buraydah 51452, Saudi Arabia
| | | | - Taghrid Istivan
- School of Science, STEM College, RMIT University, Bundoora, Melbourne, VIC 3083, Australia
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2
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The biofilm life cycle: expanding the conceptual model of biofilm formation. Nat Rev Microbiol 2022; 20:608-620. [PMID: 35922483 PMCID: PMC9841534 DOI: 10.1038/s41579-022-00767-0] [Citation(s) in RCA: 339] [Impact Index Per Article: 169.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2022] [Indexed: 01/18/2023]
Abstract
Bacterial biofilms are often defined as communities of surface-attached bacteria and are typically depicted with a classic mushroom-shaped structure characteristic of Pseudomonas aeruginosa. However, it has become evident that this is not how all biofilms develop, especially in vivo, in clinical and industrial settings, and in the environment, where biofilms often are observed as non-surface-attached aggregates. In this Review, we describe the origin of the current five-step biofilm development model and why it fails to capture many aspects of bacterial biofilm physiology. We aim to present a simplistic developmental model for biofilm formation that is flexible enough to include all the diverse scenarios and microenvironments where biofilms are formed. With this new expanded, inclusive model, we hereby introduce a common platform for developing an understanding of biofilms and anti-biofilm strategies that can be tailored to the microenvironment under investigation.
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Pereira JM, Xu S, Leong JM, Sousa S. The Yin and Yang of Pneumolysin During Pneumococcal Infection. Front Immunol 2022; 13:878244. [PMID: 35529870 PMCID: PMC9074694 DOI: 10.3389/fimmu.2022.878244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/23/2022] [Indexed: 12/15/2022] Open
Abstract
Pneumolysin (PLY) is a pore-forming toxin produced by the human pathobiont Streptococcus pneumoniae, the major cause of pneumonia worldwide. PLY, a key pneumococcal virulence factor, can form transmembrane pores in host cells, disrupting plasma membrane integrity and deregulating cellular homeostasis. At lytic concentrations, PLY causes cell death. At sub-lytic concentrations, PLY triggers host cell survival pathways that cooperate to reseal the damaged plasma membrane and restore cell homeostasis. While PLY is generally considered a pivotal factor promoting S. pneumoniae colonization and survival, it is also a powerful trigger of the innate and adaptive host immune response against bacterial infection. The dichotomy of PLY as both a key bacterial virulence factor and a trigger for host immune modulation allows the toxin to display both "Yin" and "Yang" properties during infection, promoting disease by membrane perforation and activating inflammatory pathways, while also mitigating damage by triggering host cell repair and initiating anti-inflammatory responses. Due to its cytolytic activity and diverse immunomodulatory properties, PLY is integral to every stage of S. pneumoniae pathogenesis and may tip the balance towards either the pathogen or the host depending on the context of infection.
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Affiliation(s)
- Joana M. Pereira
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Molecular and Cellular (MC) Biology PhD Program, ICBAS - Instituto de Ciência Biomédicas Abel Salazar, University of Porto, Porto, Portugal
| | - Shuying Xu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States
- Graduate Program in Immunology, Tufts Graduate School of Biomedical Sciences, Boston, MA, United States
| | - John M. Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, United States
| | - Sandra Sousa
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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Luan C, Jiang N, Zhou X, Zhang C, Zhao Y, Li Z, Li C. Antibacterial and anti-biofilm activities of probiotic Lactobacillus curvatus BSF206 and Pediococcus pentosaceus AC1-2 against Streptococcus mutans. Microb Pathog 2022; 164:105446. [DOI: 10.1016/j.micpath.2022.105446] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/08/2022] [Accepted: 02/08/2022] [Indexed: 12/01/2022]
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Hijacking host components for bacterial biofilm formation: An advanced mechanism. Int Immunopharmacol 2021; 103:108471. [PMID: 34952466 DOI: 10.1016/j.intimp.2021.108471] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/12/2022]
Abstract
Biofilm is a community of bacteria embedded in the extracellular matrix that accounts for 80% of bacterial infections. Biofilm enables bacterial cells to provide particular conditions and produce virulence determinants in response to the unavailability of micronutrients and local oxygen, resulting in their resistance to various antibacterial agents. Besides, the human immune reactions are not completely competent in the elimination of biofilm. Most importantly, the growing body of evidence shows that some bacterial spp. use a variety of mechanisms by which hijack the host components to form biofilm. In this regard, host components, such as DNA, hyaluronan, collagen, fibronectin, mucin, oligosaccharide moieties, filamentous polymers (F-actin), plasma, platelets, keratin, sialic acid, laminin, vitronectin, C3- and C4- binding proteins, antibody, proteases, factor I, factor H, and acidic proline-rich proteins have been reviewed. Hence, the characterization of interactions between bacterial biofilm and the host would be critical to effectively address biofilm-associated infections. In this paper, we review the latest information on the hijacking of host factors by bacteria to form biofilm.
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Hall DC, Król JE, Cahill JP, Ji HF, Ehrlich GD. The Development of a Pipeline for the Identification and Validation of Small-Molecule RelA Inhibitors for Use as Anti-Biofilm Drugs. Microorganisms 2020; 8:microorganisms8091310. [PMID: 32872142 PMCID: PMC7563162 DOI: 10.3390/microorganisms8091310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/22/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022] Open
Abstract
Biofilm infections have no approved effective medical treatments and can only be disrupted via physical means. This means that any biofilm infection that is not addressable surgically can never be eliminated and can only be managed as a chronic disease. Therefore, there is an urgent need for the development of new classes of drugs that can target the metabolic mechanisms within biofilms which render them recalcitrant to traditional antibiotics. Persister cells within the biofilm structure may play a large role in the enhanced antibiotic recalcitrance of bacteria biofilms. Biofilm persister cells can be resistant to up to 1000 times the minimal inhibitory concentrations of many antibiotics, as compared to their planktonic envirovars; they are thought to be the prokaryotic equivalent of metazoan stem cells. Their metabolic resistance has been demonstrated to be an active process induced by the stringent response that is triggered by the ribosomally-associated enzyme RelA in response to amino acid starvation. This 84-kD pyrophosphokinase produces the “magic spot” alarmones, collectively called (p)ppGpp. These alarmones act by directly regulating transcription by binding to RNA polymerase. These transcriptional changes lead to a major shift in cellular function to both upregulate oxidative stress-combating enzymes and down regulate major cellular functions associated with growth and replication. These changes in gene expression produce the quiescent persister cells. In this work, we describe a hybrid in silico laboratory pipeline for identifying and validating small-molecule inhibitors of RelA for use in the combinatorial treatment of bacterial biofilms as re-potentiators of classical antibiotics.
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Affiliation(s)
- Donald C. Hall
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA; (D.C.H.J.); (J.P.C.)
- Department of Microbiology & Immunology, Center for Advanced Microbial Processing, Drexel University, Philadelphia, PA 19102, USA;
- Center for Genomic Sciences, Drexel University, Philadelphia, PA 19102, USA
- Center for Surgical Infections and Bacterial Biofilms, Institute of Molecular Medicine, and Infectious Disease, Drexel University, Philadelphia, PA 19102, USA
| | - Jarosław E. Król
- Department of Microbiology & Immunology, Center for Advanced Microbial Processing, Drexel University, Philadelphia, PA 19102, USA;
- Center for Genomic Sciences, Drexel University, Philadelphia, PA 19102, USA
- Center for Surgical Infections and Bacterial Biofilms, Institute of Molecular Medicine, and Infectious Disease, Drexel University, Philadelphia, PA 19102, USA
| | - John P. Cahill
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA; (D.C.H.J.); (J.P.C.)
| | - Hai-Feng Ji
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA; (D.C.H.J.); (J.P.C.)
- Correspondence: (H.-F.J.); (G.D.E.); Tel.: +215-895-2562 (H.-F.J.); +215-762-1878 (G.D.E.)
| | - Garth D. Ehrlich
- Department of Microbiology & Immunology, Center for Advanced Microbial Processing, Drexel University, Philadelphia, PA 19102, USA;
- Center for Genomic Sciences, Drexel University, Philadelphia, PA 19102, USA
- Center for Surgical Infections and Bacterial Biofilms, Institute of Molecular Medicine, and Infectious Disease, Drexel University, Philadelphia, PA 19102, USA
- Department of Otolaryngology-Head and Neck Surgery, Drexel University College of Medicine, Drexel University, Philadelphia, PA 19102, USA
- Correspondence: (H.-F.J.); (G.D.E.); Tel.: +215-895-2562 (H.-F.J.); +215-762-1878 (G.D.E.)
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Yadav MK, Go YY, Chae SW, Park MK, Song JJ. Asian Sand Dust Particles Increased Pneumococcal Biofilm Formation in vitro and Colonization in Human Middle Ear Epithelial Cells and Rat Middle Ear Mucosa. Front Genet 2020; 11:323. [PMID: 32391052 PMCID: PMC7193691 DOI: 10.3389/fgene.2020.00323] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 03/18/2020] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Air pollutants such as Asian sand dust (ASD) and Streptococcus pneumoniae are risk factors for otitis media (OM). In this study, we evaluate the role of ASD in pneumococcal in vitro biofilm growth and colonization on human middle ear epithelium cells (HMEECs) and rat middle ear using the rat OM model. METHODS S. pneumoniae D39 in vitro biofilm growth in the presence of ASD (50-300 μg/ml) was evaluated in metal ion-free BHI medium using CV-microplate assay, colony-forming unit (cfu) counts, resazurin staining, scanning electron microscopy (SEM), and confocal microscopy (CF). Biofilm gene expression analysis was performed using real-time RT-PCR. The effects of ASD or S. pneumoniae individually or on co-treatment on HMEECs were evaluated by detecting HMEEC viability, apoptosis, and reactive oxygen species (ROS) production. In vivo colonization of S. pneumoniae in the presence of ASD was evaluated using the rat OM model, and RNA-Seq was used to evaluate the alterations in gene expression in rat middle ear mucosa. RESULTS S. pneumoniae biofilm growth was significantly (P < 0.05) elevated in the presence of ASD. SEM and CF analysis revealed thick and organized pneumococcal biofilms in the presence of ASD (300 μg/ml). However, in the absence of ASD, bacteria were unable to form organized biofilms, the cell size was smaller than normal, and long chain-like structures were formed. Biofilms grown in the presence of ASD showed elevated expression levels of genes involved in biofilm formation (luxS), competence (comA, comB, ciaR), and toxin production (lytA and ply). Prior exposure of HMEECs to ASD, followed by treatment for pneumococci, significantly (P < 0.05) decreased cell viability and increased apoptosis, and ROS production. In vivo experiment results showed significantly (P < 0.05) more than 65% increased bacteria colonization in rat middle ear mucosa in the presence of ASD. The apoptosis, cell death, DNA repair, inflammation and immune response were differentially regulated in three treatments; however, number of genes expressed in co-treatments was higher than single treatment. In co-treatment, antimicrobial protein/peptide-related genes (S100A family, Np4, DEFB family, and RATNP-3B) and OM-related genes (CYLD, SMAD, FBXO11, and CD14) were down regulated, and inflammatory cytokines and interleukins, such as IL1β, and TNF-related gene expression were elevated. CONCLUSION ASD presence increased the generation of pneumococcal biofilms and colonization.
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Affiliation(s)
- Mukesh Kumar Yadav
- Institute for Medical Device Clinical Trials, Korea University College of Medicine, Seoul, South Korea
- Department of Biotechnology, Pachhunga University College, Mizoram Central University, Aizawl, India
| | - Yoon Young Go
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Sung-Won Chae
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Moo Kyun Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul, South Korea
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
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Silva MD, Sillankorva S. Otitis media pathogens – A life entrapped in biofilm communities. Crit Rev Microbiol 2019; 45:595-612. [DOI: 10.1080/1040841x.2019.1660616] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Maria Daniela Silva
- CEB – Centre of Biological Engineering, LIBRO – Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Braga, Portugal
| | - Sanna Sillankorva
- CEB – Centre of Biological Engineering, LIBRO – Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Braga, Portugal
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Hadpanus P, Permsirivisarn P, Roytrakul S, Tungpradabkul S. Biomarker discovery in the biofilm-forming process of Burkholderia pseudomallei by mass-spectrometry. J Microbiol Methods 2019; 159:26-33. [PMID: 30797019 DOI: 10.1016/j.mimet.2019.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/18/2019] [Accepted: 02/19/2019] [Indexed: 10/27/2022]
Abstract
A serious human infectious disease called Melioidosis is a result of Burkholderia pseudomallei infection. Treatment for infected individuals is difficult due to a wide range of ineffective antibiotics including a high level of antibiotic tolerance which has been known to be caused by biofilm production. However, biofilm forming processes of this bacterium are not well documented despite multiple-methodologies being applied. In this study, we utilized a proteomics strategy called whole cell matrix-assisted laser desorption ionization-time of flight mass spectrometry (whole cell MALDI-TOF MS) to discover a potential biomarker relating biofilm forming in B. pseudomallei. The results presented a novel specific type of enzyme amylo-alpha-1, 6-glucosidase, which was demonstrated by a higher level of gene expression during the biofilm development. Our results also suggested a list of candidate markers that might be involved in this scenario. Eventually, this knowledge may expand valuable data to the biofilm study that may increase effective treatments for people infected with B. pseudomallei and possibly other antibiotic tolerant bacteria.
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Affiliation(s)
- Piyapong Hadpanus
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Sitthiruk Roytrakul
- National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand Science Park, Pathum Thani, Thailand.
| | - Sumalee Tungpradabkul
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
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10
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Kamarudheen N, Rao KB. Fatty acyl compounds from marine Streptomyces griseoincarnatus strain HK12 against two major bio-film forming nosocomial pathogens; an in vitro and in silico approach. Microb Pathog 2019; 127:121-130. [DOI: 10.1016/j.micpath.2018.11.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 10/27/2022]
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11
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Vermee Q, Cohen R, Hays C, Varon E, Bonacorsi S, Bechet S, Thollot F, Corrard F, Poyart C, Levy C, Raymond J. Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae isolated from the nasopharynx of children with acute otitis media. BMC Infect Dis 2019; 19:44. [PMID: 30634919 PMCID: PMC6329076 DOI: 10.1186/s12879-018-3657-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 12/26/2018] [Indexed: 12/13/2022] Open
Abstract
Background Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae has been implicated in the pathogenesis of otitis media, mainly in chronic and recurrent cases. We studied the “in vitro” biofilm production by these 2 species isolated alone or together from the nasopharynx of children with acute otitis media. Methods The studied strains were from 3 pneumococcal conjugate vaccine (PCV) periods: pre-PCV7, post-PCV7/pre-PCV13 and post-PCV13. A modified microtiter plate assay with crystal violet stain was used to study the biofilm production of 182 H. influenzae and 191 S. pneumoniae strains. Results Overall, 117/181 (64.6%) H. influenzae and 128/191 (66.8%) S. pneumoniae strains produced biofilm. The proportion of biofilm-producing H. influenzae strains was greater with than without the isolation of S. pneumoniae in the same sample (75.5% vs 52.3%, p = 0.001). Conversely, the proportion of biofilm-producing S. pneumoniae strains was not affected by the presence or not of H. influenzae (66.3% vs 67.4%). S. pneumoniae serotypes 6B, 15B/C, 19A, 35F and 35B were the better biofilm producers (80%). Serotypes 11A, 14, 15A, 19F and 19A were more associated with H. influenzae biofilm-producing strains. Overall, 89/94 (94.6%) of cases with combined isolation showed biofilm production by S. pneumoniae or H. influenzae. Conclusion This study emphasizes the high proportion of biofilm production by H. influenzae and S. pneumoniae strains isolated from the nasopharynx of children with acute otitis media, which reinforces the results of studies suggesting the importance of biofilm in the pathogenesis of acute otitis media. Electronic supplementary material The online version of this article (10.1186/s12879-018-3657-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Quentin Vermee
- Bactériologie, Hôpital Cochin, Université Paris Descartes, 27 rue du Faubourg Saint Jacques, 75679, Paris Cedex 14, France
| | - Robert Cohen
- Association Clinique et Thérapeutique Infantile du Val de Marne (ACTIV), 94 Saint-Maur des Fossés, France.,IMRB- GRC GEMINI, Clinical Research Center (CRC), Centre Hospitalier Intercommunal de Créteil, Université Paris Est, Créteil, France.,Service de Néonatologie, Centre Hospitalier Intercommunal de Créteil, Créteil, France
| | - Constantin Hays
- Bactériologie, Hôpital Cochin, Université Paris Descartes, 27 rue du Faubourg Saint Jacques, 75679, Paris Cedex 14, France
| | - Emmanuelle Varon
- Bactériologie, Hôpital Georges Pompidou, Université Paris Descartes, Paris, France
| | | | - Stephane Bechet
- Association Clinique et Thérapeutique Infantile du Val de Marne (ACTIV), 94 Saint-Maur des Fossés, France
| | | | - François Corrard
- Association Clinique et Thérapeutique Infantile du Val de Marne (ACTIV), 94 Saint-Maur des Fossés, France
| | - Claire Poyart
- Bactériologie, Hôpital Cochin, Université Paris Descartes, 27 rue du Faubourg Saint Jacques, 75679, Paris Cedex 14, France
| | - Corinne Levy
- Association Clinique et Thérapeutique Infantile du Val de Marne (ACTIV), 94 Saint-Maur des Fossés, France.,IMRB- GRC GEMINI, Clinical Research Center (CRC), Centre Hospitalier Intercommunal de Créteil, Université Paris Est, Créteil, France
| | - Josette Raymond
- Bactériologie, Hôpital Cochin, Université Paris Descartes, 27 rue du Faubourg Saint Jacques, 75679, Paris Cedex 14, France.
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Chao Y, Bergenfelz C, Hakansson AP. Growing and Characterizing Biofilms Formed by Streptococcus pneumoniae. Methods Mol Biol 2019; 1968:147-171. [PMID: 30929213 DOI: 10.1007/978-1-4939-9199-0_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It is estimated that over 80% of bacterial infections are associated with biofilm formation. Biofilms are organized bacterial communities formed on abiotic surfaces, such as implanted or inserted medical devices, or on biological surfaces, such as epithelial linings and mucosal surfaces. Biofilm growth is advantageous for the bacterial organism as it protects the bacteria from antimicrobial host factors and allows the bacteria to reside in the host without causing excessive inflammation. Like many other opportunistic pathogens of the respiratory tract, Streptococcus pneumoniae forms biofilms during asymptomatic carriage, which promotes, among other things, persistence in the niche, intraspecies and interspecies communication, and spread of bacterial DNA. Changes within the colonizing environment resulting from host assaults, such as virus infection, can induce biofilm dispersion where bacteria leave the biofilm and disseminate to other sites with ensuing infection. In this chapter, we present methodology to form complex biofilms in the nasopharynx of mice and to evaluate the biofilm structure and function in this environment. Furthermore, we present methods that recapitulate this biofilm phenotype in vitro by incorporating crucial factors associated with the host environment and describe how these models can be used to study biofilm function, transformation, and dispersion.
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Affiliation(s)
- Yashuan Chao
- Wallenberg Laboratory, Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Caroline Bergenfelz
- Wallenberg Laboratory, Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Anders P Hakansson
- Wallenberg Laboratory, Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University, Malmö, Sweden.
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13
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Dennis EA, Coats MT, Griffin S, Pang B, Briles DE, Crain MJ, Swords WE. Hyperencapsulated mucoid pneumococcal isolates from patients with cystic fibrosis have increased biofilm density and persistence in vivo. Pathog Dis 2018; 76:5110111. [PMID: 30265307 DOI: 10.1093/femspd/fty073] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/27/2018] [Indexed: 12/30/2022] Open
Abstract
Mucoid bacteria, predominately Pseudomonas aeruginosa, are commonly associated with decline in pulmonary function in children with cystic fibrosis (CF), and are thought to persist at least in part due to a greater propensity toward forming biofilms. We isolated a higher frequency of mucoid Streptococcus pneumoniae (Sp) expressing high levels of capsular polysaccharides from sputa from children with CF, compared to those without CF. We compared biofilm formation and maturation by mucoid and non-mucoid isolates of Sp collected from children with and without CF. Non-mucoid Sp serotype 19A and 19F isolates had significantly higher levels of biofilm initiation and adherence to CF epithelial cells than did serotype 3 isolates. However, strains expressing high levels of capsule had significantly greater biofilm maturation, as evidenced by increased density and thickness in static and continuous flow assays via confocal microscopy. Finally, using a serotype 3 Sp strain, we showed that highly encapsulated mucoid phase variants predominate during late adherence and better colonize CFTR-/- as compared to wild-type mice in respiratory infection studies. These findings indicate that overexpression of capsule can enhance the development of mature pneumococcal biofilms in vitro, and may contribute to pneumococcal colonization in CF lung disease.
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Affiliation(s)
- Evida A Dennis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham AL 35233, USA
| | - Mamie T Coats
- Department of Biological Sciences, Alabama State University, Montgomery, AL 36104-5732, USA
| | - Sarah Griffin
- Department of Microbiology, University of Alabama at Birmingham, Birmingham AL 35233, USA
| | - Bing Pang
- Department of Microbiology and Immunology, Wake Forest University Baptist Medical Center, 575 North Patterson Avenue, Winston-Salem, NC 27101, USA
| | - David E Briles
- Department of Microbiology, University of Alabama at Birmingham, Birmingham AL 35233, USA.,Division of Infections Diseases, Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Marilyn J Crain
- Division of Infections Diseases, Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - W Edward Swords
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA
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14
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Cools F, Torfs E, Vanhoutte B, de Macedo MB, Bonofiglio L, Mollerach M, Maes L, Caljon G, Delputte P, Cappoen D, Cos P. Streptococcus pneumoniae galU gene mutation has a direct effect on biofilm growth, adherence and phagocytosis in vitro and pathogenicity in vivo. Pathog Dis 2018; 76:5078866. [DOI: 10.1093/femspd/fty069] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 08/22/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- F Cools
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - E Torfs
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - B Vanhoutte
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - M Bidart de Macedo
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - L Bonofiglio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética. Cátedra de Microbiología. Junín 956. Ciudad Autónoma de Buenos Aires, Argentina
| | - M Mollerach
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética. Cátedra de Microbiología. Junín 956. Ciudad Autónoma de Buenos Aires, Argentina
| | - L Maes
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - G Caljon
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - P Delputte
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - D Cappoen
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - P Cos
- University of Antwerp, Laboratory of Microbiology, Parasitology and Hygiene. Universiteitsplein 1, 2610 Wilrijk, Belgium
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15
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Newby RS, Dryden M, Allan RN, Salib RJ. Antimicrobial activity of a novel bioengineered honey against non-typeable Haemophilus influenzae biofilms: an in vitro study. J Clin Pathol 2018; 71:554-558. [PMID: 29449345 DOI: 10.1136/jclinpath-2017-204901] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/19/2018] [Accepted: 01/29/2018] [Indexed: 11/04/2022]
Abstract
The opportunistic pathogen non-typeable Haemophilus influenzae (NTHi) plays an important role in many chronic respiratory diseases including otitis media, chronic rhinosinusitis, cystic fibrosis and chronic obstructive pulmonary disease. Biofilm formation has been implicated in NTHi colonisation, persistence of infection and recalcitrance towards antimicrobials. There is therefore a pressing need for the development of novel treatment strategies that are effective against NTHi biofilm-associated diseases. SurgihoneyRO is a honey-based product that has been bioengineered to enable the slow release of H2O2, a reactive oxygen species to which H. influenzae is susceptible. Treatment of established NTHi biofilms with SurgihoneyRO significantly reduced biofilm viability through enhanced H2O2 production and was shown to be more effective than the conventional antibiotic co-amoxiclav.
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Affiliation(s)
- Rachel S Newby
- Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, UK
| | - Matthew Dryden
- Hampshire Hospitals NHS Foundation Trust, Winchester, UK.,University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Raymond N Allan
- Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, UK.,Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Rami J Salib
- University Hospital Southampton NHS Foundation Trust, Southampton, UK.,Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK
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16
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Abstract
Over half of the nearly two million healthcare-associated infections can be attributed to indwelling medical devices. In this review, we highlight the difficulty in diagnosing implantable device-related infection and how this leads to a likely underestimate of the prevalence. We then provide a length-scale conceptualization of device-related infection pathogenesis. Within this conceptualization we focus specifically on biofilm formation and the role of host immune and coagulation systems. Using this framework, we describe how current and developing preventative strategies target specific processes along the entire length-scale. In light of the significant time horizon for the development and translation of new preventative technologies, we also emphasize the need for parallel development of in situ treatment strategies. Specific examples of both preventative and treatment strategies and how they align with the length-scale conceptualization are described.
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17
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Streptococcus pneumoniae TIGR4 Phase-Locked Opacity Variants Differ in Virulence Phenotypes. mSphere 2017; 2:mSphere00386-17. [PMID: 29152579 PMCID: PMC5687919 DOI: 10.1128/msphere.00386-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 09/13/2017] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is a leading human pathogen that can cause serious localized and invasive diseases. Pneumococci can undergo a spontaneous and reversible phase variation that is reflected in colony opacity and which allows the population to adapt to different host environments. Generally, transparent variants are adapted for nasopharyngeal colonization, whereas opaque variants are associated with invasive disease. In recent work, colony phase variation was shown to occur by means of recombination events to generate multiple alleles of the hsdS targeting domain of a DNA methylase complex, which mediates epigenetic changes in gene expression. A panel of isogenic strains were created in the well-studied S. pneumoniae TIGR4 background that are "locked" in the transparent (n = 4) or opaque (n = 2) colony phenotype. The strains had significant differences in colony size which were stable over multiple passages in vitro and in vivo. While there were no significant differences in adherence for the phase-locked mutant strains to immortalized epithelial cells, biofilm formation and viability were reduced for the opaque variants in static assays. Nasopharyngeal colonization was stable for all strains, but the mortality rates differed between them. Transcript profiling by transcriptome sequencing (RNA-seq) analyses revealed that the expression levels of certain virulence factors were increased in a phase-specific manner. As epigenetic regulation of phase variation (often referred to as "phasevarion") is emerging as a common theme for mucosal pathogens, these results serve as a model for future studies of host-pathogen interactions. IMPORTANCE A growing number of bacterial species undergo epigenetic phase variation due to variable expression or specificity of DNA-modifying enzymes. For pneumococci, this phase variation has long been appreciated as being revealed by changes in colony opacity, which are reflected in changes in expression or accessibility of factors on the bacterial surface. Recent work showed that recombination-generated variation in alleles of the HsdS DNA methylase specificity subunit mediated pneumococcal phase variation. We generated phase-locked populations of S. pneumoniae TIGR4 expressing a single nonvariant hsdS allele and observed significant differences in gene expression and virulence. These results highlight the importance of focused pathogenesis studies within specific phase types. Moreover, the generation of single-allele hsdS constructs will greatly facilitate such studies.
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18
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RpoN (σ 54) Is Required for Floc Formation but Not for Extracellular Polysaccharide Biosynthesis in a Floc-Forming Aquincola tertiaricarbonis Strain. Appl Environ Microbiol 2017; 83:AEM.00709-17. [PMID: 28500044 DOI: 10.1128/aem.00709-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 05/08/2017] [Indexed: 11/20/2022] Open
Abstract
Some bacteria are capable of forming flocs, in which bacterial cells become self-flocculated by secreted extracellular polysaccharides and other biopolymers. The floc-forming bacteria play a central role in activated sludge, which has been widely utilized for the treatment of municipal sewage and industrial wastewater. Here, we use a floc-forming bacterium, Aquincolatertiaricarbonis RN12, as a model to explore the biosynthesis of extracellular polysaccharides and the regulation of floc formation. A large gene cluster for exopolysaccharide biosynthesis and a gene encoding the alternative sigma factor RpoN1, one of the four paralogues, have been identified in floc formation-deficient mutants generated by transposon mutagenesis, and the gene functions have been further confirmed by genetic complementation analyses. Interestingly, the biosynthesis of exopolysaccharides remained in the rpoN1-disrupted flocculation-defective mutants, but most of the exopolysaccharides were secreted and released rather than bound to the cells. Furthermore, the expression of exopolysaccharide biosynthesis genes seemed not to be regulated by RpoN1. Taken together, our results indicate that RpoN1 may play a role in regulating the expression of a certain gene(s) involved in the self-flocculation of bacterial cells but not in the biosynthesis and secretion of exopolysaccharides required for floc formation.IMPORTANCE Floc formation confers bacterial resistance to predation of protozoa and plays a central role in the widely used activated sludge process. In this study, we not only identified a large gene cluster for biosynthesis of extracellular polysaccharides but also identified four rpoN paralogues, one of which (rpoN1) is required for floc formation in A. tertiaricarbonis RN12. In addition, this RpoN sigma factor regulates the transcription of genes involved in biofilm formation and swarming motility, as previously shown in other bacteria. However, this RpoN paralogue is not required for the biosynthesis of exopolysaccharides, which are released and dissolved into culture broth by the rpoN1 mutant rather than remaining tightly bound to cells, as observed during the flocculation of the wild-type strain. These results indicate that floc formation is a regulated complex process, and other yet-to-be identified RpoN1-dependent factors are involved in self-flocculation of bacterial cells via exopolysaccharides and/or other biopolymers.
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Ngo Ndjom CG, Kantor LV, Jones HP. CRH Affects the Phenotypic Expression of Sepsis-Associated Virulence Factors by Streptococcus pneumoniae Serotype 1 In vitro. Front Cell Infect Microbiol 2017; 7:263. [PMID: 28690980 PMCID: PMC5479890 DOI: 10.3389/fcimb.2017.00263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/02/2017] [Indexed: 12/20/2022] Open
Abstract
Sepsis is a life-threatening health condition caused by infectious pathogens of the respiratory tract, and accounts for 28–50% of annual deaths in the US alone. Current treatment regimen advocates the use of corticosteroids as adjunct treatment with antibiotics, for their broad inhibitory effect on the activity and production of pro-inflammatory mediators. However, despite their use, corticosteroids have not proven to be able to reverse the death incidence among septic patients. We have previously demonstrated the potential for neuroendocrine factors to directly influence Streptococcus pneumoniae virulence, which may in turn mediate disease outcome leading to sepsis and septic shock. The current study investigated the role of Corticotropin-releasing hormone (CRH) in mediating key markers of pneumococcal virulence as important phenotypic determinants of sepsis and septic shock risks. In vitro cultures of serotype 1 pneumococcal strain with CRH promoted growth rate, increased capsule thickness and penicillin resistance, as well as induced pneumolysin gene expression. These results thus provide significant insights of CRH–pathogen interactions useful in understanding the underlying mechanisms of neuroendocrine factor's role in the onset of community acquired pneumonias (CAP), sepsis and septic shock.
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Affiliation(s)
- Colette G Ngo Ndjom
- Department of Molecular and Medical Genetics, University of North Texas Health Science CenterFort Worth, TX, United States
| | - Lindsay V Kantor
- Graduate School of Biomedical Sciences, University of North Texas Health Science CenterFort Worth, TX, United States
| | - Harlan P Jones
- Department of Molecular and Medical Genetics, University of North Texas Health Science CenterFort Worth, TX, United States
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20
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Sadiq FA, Flint S, Li Y, Liu T, Lei Y, Sakandar HA, He G. New mechanistic insights into the motile-to-sessile switch in various bacteria with particular emphasis on Bacillus subtilis and Pseudomonas aeruginosa: a review. BIOFOULING 2017; 33:306-326. [PMID: 28347177 DOI: 10.1080/08927014.2017.1304541] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/04/2017] [Indexed: 06/06/2023]
Abstract
A biofilm is a complex assemblage of microbial communities adhered to a biotic or an abiotic surface which is embedded within a self-produced matrix of extracellular polymeric substances. Many transcriptional regulators play a role in triggering a motile-sessile switch and in consequently producing the biofilm matrix. This review is aimed at highlighting the role of two nucleotide signaling molecules (c-di-GMP and c-di-AMP), toxin antitoxin modules and a novel transcriptional regulator BolA in biofilm formation in various bacteria. In addition, it highlights the common themes that have appeared in recent research regarding the key regulatory components and signal transduction pathways that help Bacillus subtilis and Pseudomonas aeruginosa to acquire the biofilm mode of life.
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Affiliation(s)
- Faizan A Sadiq
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | - Steve Flint
- b School of Food and Nutrition , Massey University , Palmerston North , New Zealand
| | - Yun Li
- c School of Life Sciences and Food Technology , Hanshan Normal University , Chaozhou , PR China
| | - TongJie Liu
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | - Yuan Lei
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
| | | | - GuoQing He
- a College of Biosystems Engineering and Food Science , Zhejiang University , Hangzhou , PR China
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21
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22
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Lees JA, Kremer PHC, Manso AS, Croucher NJ, Ferwerda B, Serón MV, Oggioni MR, Parkhill J, Brouwer MC, van der Ende A, van de Beek D, Bentley SD. Large scale genomic analysis shows no evidence for pathogen adaptation between the blood and cerebrospinal fluid niches during bacterial meningitis. Microb Genom 2017; 3:e000103. [PMID: 28348877 PMCID: PMC5361624 DOI: 10.1099/mgen.0.000103] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 12/18/2016] [Indexed: 12/26/2022] Open
Abstract
Recent studies have provided evidence for rapid pathogen genome diversification, some of which could potentially affect the course of disease. We have previously described such variation seen between isolates infecting the blood and cerebrospinal fluid (CSF) of a single patient during a case of bacterial meningitis. Here, we performed whole-genome sequencing of paired isolates from the blood and CSF of 869 meningitis patients to determine whether such variation frequently occurs between these two niches in cases of bacterial meningitis. Using a combination of reference-free variant calling approaches, we show that no genetic adaptation occurs in either invaded niche during bacterial meningitis for two major pathogen species, Streptococcus pneumoniae and Neisseria meningitidis. This study therefore shows that the bacteria capable of causing meningitis are already able to do this upon entering the blood, and no further sequence change is necessary to cross the blood–brain barrier. Our findings place the focus back on bacterial evolution between nasopharyngeal carriage and invasion, or diversity of the host, as likely mechanisms for determining invasiveness.
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Affiliation(s)
- John A Lees
- 1Pathogen Genomics, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Philip H C Kremer
- 2Department of Neurology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, The Netherlands
| | - Ana S Manso
- 3Department of Genetics, University of Leicester, Leicester, UK
| | - Nicholas J Croucher
- 4Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Bart Ferwerda
- 2Department of Neurology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, The Netherlands
| | - Mercedes Valls Serón
- 2Department of Neurology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, The Netherlands
| | - Marco R Oggioni
- 3Department of Genetics, University of Leicester, Leicester, UK
| | - Julian Parkhill
- 1Pathogen Genomics, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Matthijs C Brouwer
- 2Department of Neurology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, The Netherlands
| | - Arie van der Ende
- 5Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, The Netherlands.,6Netherlands Reference Laboratory for Bacterial Meningitis, Academic Medical Center, Amsterdam, The Netherlands
| | - Diederik van de Beek
- 2Department of Neurology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, Amsterdam, The Netherlands
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23
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Millares L, Bermudo G, Pérez-Brocal V, Domingo C, Garcia-Nuñez M, Pomares X, Moya A, Monsó E. The respiratory microbiome in bronchial mucosa and secretions from severe IgE-mediated asthma patients. BMC Microbiol 2017; 17:20. [PMID: 28103814 PMCID: PMC5248442 DOI: 10.1186/s12866-017-0933-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 01/13/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The bronchial microbiome in chronic lung diseases presents an abnormal pattern, but its microbial composition and regional differences in severe asthma have not been sufficiently addressed. The aim of the study was to describe the bacterial community in bronchial mucosa and secretions of patients with severe chronic asthma chronically treated with corticosteroids in addition to usual care according to Global Initiative for Asthma. Bacterial community composition was obtained by 16S rRNA gene amplification and sequencing, and functional capabilities through PICRUSt. RESULTS Thirteen patients with severe asthma were included and provided 11 bronchial biopsies (BB) and 12 bronchial aspirates (BA) suitable for sequence analyses. Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria showed relative abundances (RAs) over 5% in BB, a cutoff that was reached by Streptococcus and Prevotella at genus level. Legionella genus attained a median RA of 2.7 (interquartile range 1.1-4.7) in BB samples. In BA a higher RA of Fusobacteria was found, when compared with BB [8.7 (5.9-11.4) vs 4.2 (0.8-7.5), p = 0.037], while the RA of Proteobacteria was lower in BA [4.3 (3.7-6.5) vs 17.1 (11.2-33.4), p = 0.005]. RA of the Legionella genus was also significantly lower in BA [0.004 (0.001-0.02) vs. 2.7 (1.1-4.7), p = 0.005]. Beta-diversity analysis confirmed the differences between the microbial communities in BA and BB (R2 = 0.20, p = 0.001, Adonis test), and functional analysis revealed also statistically significant differences between both types of sample on Metabolism, Cellular processes, Human diseases, Organismal systems and Genetic information processing pathways. CONCLUSIONS The microbiota in the bronchial mucosa of severe asthma has a specific pattern that is not accurately represented in bronchial secretions, which must be considered a different niche of bacteria growth.
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Affiliation(s)
- Laura Millares
- Fundació Parc Taulí, Parc Taulí 1, Edificio Santa Fe, planta baja, 08208, Sabadell, Barcelona, Spain.
- CIBER de Enfermedades Respiratorias, CIBERES, Madrid, Spain.
- Universitat Autònoma de Barcelona, Esfera UAB, Barcelona, Spain.
- Fundació Insitut d'Investigació Germans Trias i Pujol, Badalona, Spain.
| | - Guadalupe Bermudo
- Department of Respiratory Medicine, Hospital Universitari Parc Taulí, Sabadell, Spain
| | - Vicente Pérez-Brocal
- Genomics and Health Area, Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO-Public Health), Valencia, Spain
- CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Evolutionary Genetics Unit, Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
| | - Christian Domingo
- Department of Respiratory Medicine, Hospital Universitari Parc Taulí, Sabadell, Spain
- Department of Medicine, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Marian Garcia-Nuñez
- Fundació Parc Taulí, Parc Taulí 1, Edificio Santa Fe, planta baja, 08208, Sabadell, Barcelona, Spain
- CIBER de Enfermedades Respiratorias, CIBERES, Madrid, Spain
- Universitat Autònoma de Barcelona, Esfera UAB, Barcelona, Spain
- Fundació Insitut d'Investigació Germans Trias i Pujol, Badalona, Spain
| | - Xavier Pomares
- Department of Respiratory Medicine, Hospital Universitari Parc Taulí, Sabadell, Spain
| | - Andrés Moya
- Genomics and Health Area, Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO-Public Health), Valencia, Spain
- CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Evolutionary Genetics Unit, Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
| | - Eduard Monsó
- CIBER de Enfermedades Respiratorias, CIBERES, Madrid, Spain
- Universitat Autònoma de Barcelona, Esfera UAB, Barcelona, Spain
- Department of Medicine, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
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24
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Chao Y, Bergenfelz C, Håkansson AP. In Vitro and In Vivo Biofilm Formation by Pathogenic Streptococci. Methods Mol Biol 2017; 1535:285-299. [PMID: 27914087 DOI: 10.1007/978-1-4939-6673-8_19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
This manuscript presents novel approaches to grow and evaluate Streptococcal biofilm formation using the human respiratory pathogen Streptococcus pneumoniae (the pneumococcus) as the main model organism on biological surfaces in vitro and in vivo. Most biofilm models are based on growth on abiotic surfaces, which is relevant for many pathogens whose growth on surfaces or medical devices is a major cause of disease transmission and infections, especially in hospital environments. However, most infections with commensal organisms require biofilm formation on biological surfaces in the host at the site of colonization or infection. In vitro model systems incorporating biological components from the host and taking into account the host environment of the infectious site are not well described.In a series of publications, we have shown that S. pneumoniae form complex biofilms in the nasopharynx of mice and have devised methodology to evaluate the biofilm structure and function in this environment. We have also been able to recapitulate this biofilm phenotype in vitro by incorporating crucial factors associated with the host environment. Although the protocols presented in this manuscript are focused on S. pneumoniae, the same methodology can and has been used for other Streptococcal species that form biofilms on mucosal surfaces.
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Affiliation(s)
- Yashuan Chao
- Division of Experimental Infection Medicine, Department of Translational Medicine, Wallenberg Laboratory, Lund University, 53 Inga Marie Nilsson Street, 20502, Malmö, Sweden
| | - Caroline Bergenfelz
- Division of Experimental Infection Medicine, Department of Translational Medicine, Wallenberg Laboratory, Lund University, 53 Inga Marie Nilsson Street, 20502, Malmö, Sweden
| | - Anders P Håkansson
- Division of Experimental Infection Medicine, Department of Translational Medicine, Wallenberg Laboratory, Lund University, 53 Inga Marie Nilsson Street, 20502, Malmö, Sweden.
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25
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Systemic immunization with rPotD reduces Streptococcus pneumoniae nasopharyngeal colonization in mice. Vaccine 2017; 35:149-155. [DOI: 10.1016/j.vaccine.2016.11.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/11/2016] [Accepted: 11/07/2016] [Indexed: 12/13/2022]
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Establishment of a multi-species biofilm model and metatranscriptomic analysis of biofilm and planktonic cell communities. Appl Microbiol Biotechnol 2016; 100:7263-79. [PMID: 27102130 DOI: 10.1007/s00253-016-7532-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/28/2016] [Accepted: 04/05/2016] [Indexed: 02/06/2023]
Abstract
We collected several biofilm samples from Japanese rivers and established a reproducible multi-species biofilm model that can be analyzed in laboratories. Bacterial abundance at the generic level was highly similar between the planktonic and biofilm communities, whereas comparative metatranscriptomic analysis revealed many upregulated and downregulated genes in the biofilm. Many genes involved in iron-sulfur metabolism, stress response, and cell envelope function were upregulated; biofilm formation is mediated by an iron-dependent signaling mechanism and the signal is relayed to stress-responsive and cell envelope function genes. Flagella-related gene expression was regulated depending upon the growth phase, indicating different roles of flagella during the adherence, maturation, and dispersal steps of biofilm formation. Downregulation of DNA repair genes was observed, indicating that spontaneous mutation frequency would be elevated within the biofilm and that the biofilm is a cradle for generating novel genetic traits. Although the significance remains unclear, genes for rRNA methyltransferase, chromosome partitioning, aminoacyl-tRNA synthase, and cysteine, methionine, leucine, thiamine, nucleotide, and fatty acid metabolism were found to be differentially regulated. These results indicate that planktonic and biofilm communities are in different dynamic states. Studies on biofilm and sessile cells, which have received less attention, are important for understanding microbial ecology and for designing tailor-made anti-biofilm drugs.
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Control of Biofilms with the Fatty Acid Signaling Molecule cis-2-Decenoic Acid. Pharmaceuticals (Basel) 2015; 8:816-35. [PMID: 26610524 PMCID: PMC4695811 DOI: 10.3390/ph8040816] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 11/11/2015] [Accepted: 11/18/2015] [Indexed: 12/26/2022] Open
Abstract
Biofilms are complex communities of microorganisms in organized structures attached to surfaces. Importantly, biofilms are a major cause of bacterial infections in humans, and remain one of the most significant challenges to modern medical practice. Unfortunately, conventional therapies have shown to be inadequate in the treatment of most chronic biofilm infections based on the extraordinary innate tolerance of biofilms to antibiotics. Antagonists of quorum sensing signaling molecules have been used as means to control biofilms. QS and other cell-cell communication molecules are able to revert biofilm tolerance, prevent biofilm formation and disrupt fully developed biofilms, albeit with restricted effectiveness. Recently however, it has been demonstrated that Pseudomonas aeruginosa produces a small messenger molecule cis-2-decenoic acid (cis-DA) that shows significant promise as an effective adjunctive to antimicrobial treatment of biofilms. This molecule is responsible for induction of the native biofilm dispersion response in a range of Gram-negative and Gram-positive bacteria and in yeast, and has been shown to reverse persistence, increase microbial metabolic activity and significantly enhance the cidal effects of conventional antimicrobial agents. In this manuscript, the use of cis-2-decenoic acid as a novel agent for biofilm control is discussed. Stimulating the biofilm dispersion response as a novel antimicrobial strategy holds significant promise for enhanced treatment of infections and in the prevention of biofilm formation.
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28
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Bittaye M, Cash P. Streptococcus pneumoniae proteomics: determinants of pathogenesis and vaccine development. Expert Rev Proteomics 2015; 12:607-21. [PMID: 26524107 DOI: 10.1586/14789450.2015.1108844] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Streptococcus pneumoniae is a major pathogen that is responsible for a variety of invasive diseases. The bacteria gain entry initially by establishing a carriage state in the nasopharynx from where they migrate to other sites in the body. The worldwide distribution of the bacteria and the severity of the diseases have led to a significant level of interest in the development of vaccines against the bacteria. Current vaccines, based on the bacterial polysaccharide, have a number of limitations including poor immunogenicity and limited effectiveness against all pneumococcal serotypes. There are many challenges in developing vaccines that will be effective against the diverse range of isolates and serotypes for this highly variable bacterial pathogen. This review considers how proteomic technologies have extended our understanding of the pathogenic mechanisms of nasopharyngeal colonization and disease development as well as the critical areas in developing protein-based vaccines.
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Affiliation(s)
- Mustapha Bittaye
- a Division of Applied Medicine , University of Aberdeen , Aberdeen , Scotland
| | - Phil Cash
- a Division of Applied Medicine , University of Aberdeen , Aberdeen , Scotland
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Mayanskiy AN, Chebotar IV, Lazareva AV, Mayanskiy NA. Biofilm formation by Streptococcus pneumoniae. MOLECULAR GENETICS MICROBIOLOGY AND VIROLOGY 2015. [DOI: 10.3103/s0891416815030040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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30
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Immunization with Pneumococcal Surface Protein K of Nonencapsulated Streptococcus pneumoniae Provides Protection in a Mouse Model of Colonization. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 22:1146-53. [PMID: 26311246 DOI: 10.1128/cvi.00456-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/24/2015] [Indexed: 01/18/2023]
Abstract
Current vaccinations are effective against encapsulated strains of Streptococcus pneumoniae, but they do not protect against nonencapsulated Streptococcus pneumoniae (NESp), which is increasing in colonization and incidence of pneumococcal disease. Vaccination with pneumococcal proteins has been assessed for its ability to protect against pneumococcal disease, but several of these proteins are not expressed by NESp. Pneumococcal surface protein K (PspK), an NESp virulence factor, has not been assessed for immunogenic potential or host modulatory effects. Mammalian cytokine expression was determined in an in vivo mouse model and in an in vitro cell culture system. Systemic and mucosal mouse immunization studies were performed to determine the immunogenic potential of PspK. Murine serum and saliva were collected to quantitate specific antibody isotype responses and the ability of antibody and various proteins to inhibit epithelial cell adhesion. Host cytokine response was not reduced by PspK. NESp was able to colonize the mouse nasopharynx as effectively as encapsulated pneumococci. Systemic and mucosal immunization provided protection from colonization by PspK-positive (PspK(+)) NESp. Anti-PspK antibodies were recovered from immunized mice and significantly reduced the ability of NESp to adhere to human epithelial cells. A protein-based pneumococcal vaccine is needed to provide broad protection against encapsulated and nonencapsulated pneumococci in an era of increasing antibiotic resistance and vaccine escape mutants. We demonstrate that PspK may serve as an NESp target for next-generation pneumococcal vaccines. Immunization with PspK protected against pneumococcal colonization, which is requisite for pneumococcal disease.
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Morrell-Falvey JL, Elkins JG, Wang ZW. Determination of the cellulase activity distribution in Clostridium thermocellum and Caldicellulosiruptor obsidiansis cultures using a fluorescent substrate. J Environ Sci (China) 2015; 34:212-218. [PMID: 26257364 DOI: 10.1016/j.jes.2015.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 03/13/2015] [Accepted: 03/16/2015] [Indexed: 06/04/2023]
Abstract
This study took advantage of resorufin cellobioside as a fluorescent substrate to determine the distribution of cellulase activity in cellulosic biomass fermentation systems. Cellulolytic biofilms were found to express nearly four orders greater cellulase activity compared to planktonic cultures of Clostridium thermocellum and Caldicellulosiruptor obsidiansis, which can be primarily attributed to the high cell concentration and surface attachment. The formation of biofilms results in cellulases being secreted close to their substrates, which appears to be an energetically favorable stategy for insoluble substrate utilization. For the same reason, cellulases should be closely associated with the surfaces of suspended cell in soluble substrate-fed culture, which has been verified with cellobiose-fed cultures of C. thermocellum and C. obsidiansis. This study addressed the importance of cellulase activity distribution in cellulosic biomass fermentation, and provided theoretical foundation for the leading role of biofilm in cellulose degradation. System optimization and reactor designs that promote biofilm formation in cellulosic biomass hydrolysis may promise an improved cellulosic biofuel process.
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Affiliation(s)
- Jennifer L Morrell-Falvey
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - James G Elkins
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zhi-Wu Wang
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA; The Ohio State University ATI, 1328 Dover Rd, Wooster, OH 44691, USA.
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Khemiri A, Jouenne T, Cosette P. Proteomics dedicated to biofilmology: What have we learned from a decade of research? Med Microbiol Immunol 2015; 205:1-19. [PMID: 26068406 DOI: 10.1007/s00430-015-0423-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 06/03/2015] [Indexed: 12/31/2022]
Abstract
Advances in proteomics techniques over the past decade, closely integrated with genomic and physicochemical approach, have played a great role in developing knowledge of the biofilm lifestyle of bacteria. Despite bacterial proteome versatility, many studies have demonstrated the ability of proteomics approaches to elucidating the biofilm phenotype. Though these investigations have been largely used for biofilm studies in the last decades, they represent, however, a very low percentage of proteomics works performed up to now. Such approaches have offered new targets for combating microbial biofilms by providing a comprehensive quantitative and qualitative overview of their protein cell content. Herein, we summarized the state of the art in knowledge about biofilm physiology after one decade of proteomic analysis. In a second part, we highlighted missing research tracks for the next decade, emphasizing the emergence of posttranslational modifications in proteomic studies stemming from recent advances in mass spectrometry-based proteomics.
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Affiliation(s)
- Arbia Khemiri
- CNRS, UMR 6270, Laboratory "Polymères, Biopolymères, Surfaces", 76820, Mont-Saint-Aignan, France.
- University of Normandy, UR, Mont-Saint-Aignan, France.
- PISSARO Proteomic Facility, IRIB, 76820, Mont-Saint-Aignan, France.
| | - Thierry Jouenne
- CNRS, UMR 6270, Laboratory "Polymères, Biopolymères, Surfaces", 76820, Mont-Saint-Aignan, France
- University of Normandy, UR, Mont-Saint-Aignan, France
- PISSARO Proteomic Facility, IRIB, 76820, Mont-Saint-Aignan, France
| | - Pascal Cosette
- CNRS, UMR 6270, Laboratory "Polymères, Biopolymères, Surfaces", 76820, Mont-Saint-Aignan, France
- University of Normandy, UR, Mont-Saint-Aignan, France
- PISSARO Proteomic Facility, IRIB, 76820, Mont-Saint-Aignan, France
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Mutations in pneumococcal cpsE generated via in vitro serial passaging reveal a potential mechanism of reduced encapsulation utilized by a conjunctival isolate. J Bacteriol 2015; 197:1781-91. [PMID: 25777672 DOI: 10.1128/jb.02602-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/05/2015] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED The polysaccharide capsule of Streptococcus pneumoniae is required for nasopharyngeal colonization and for invasive disease in the lungs, blood, and meninges. In contrast, the vast majority of conjunctival isolates are acapsular. The first serotype-specific gene in the capsule operon, cpsE, encodes the initiating glycosyltransferase and is one of the few serotype-specific genes that can tolerate null mutations. This report characterizes a spontaneously arising TIGR4 mutant exhibiting a reduced capsule, caused by a 6-nucleotide duplication in cpsE which results in duplication of Ala and Ile at positions 45 and 46. This strain (AI45dup) possessed more exposed phosphorylcholine and was hypersusceptible to C3 complement deposition compared to the wild type. Accordingly, the mutant was significantly better at forming abiotic biofilms and binding epithelial cells in vitro but was avirulent in a sepsis model. In vitro serial passaging of the wild-type strain failed to reproduce the AI45dup mutation but instead led to a variety of mutants with reduced capsule harboring single nucleotide polymorphisms (SNPs) in cpsE. A single passage in the sepsis model after high-dose inoculation readily yielded revertants of AI45dup with restored wild-type capsule level, but the majority of SNP alleles of cpsE could not revert, suppress, or bypass. Analysis of cpsE in conjunctival isolates revealed a strain with a single missense mutation at amino acid position 377, which was responsible for reduced encapsulation. This study supports the hypothesis that spontaneous, nonreverting mutations in cpsE serve as a form of adaptive mutation by providing a selective advantage to S. pneumoniae in niches where expression of capsule is detrimental. IMPORTANCE While the capsule of Streptococcus pneumoniae is required for colonization and invasive disease, most conjunctival isolates are acapsular by virtue of deletion of the entire capsular operon. We show that spontaneous acapsular mutants isolated in vitro harbor mostly nonrevertible single nucleotide polymorphism (SNP) null mutations in cpsE, encoding the initiating glycosyltransferase. From a small collection of acapsular conjunctival isolates, we identified one strain with a complete capsular operon but containing a SNP in cpsE that we show is responsible for the acapsular phenotype. We propose that acapsular conjunctival isolates may arise initially from such nonreverting SNP null mutations in cpsE, which can be followed later by deletion of portions or all of the cps operon.
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Vandevelde NM, Tulkens PM, Muccioli GG, Van Bambeke F. Modulation of the activity of moxifloxacin and solithromycin in an in vitro pharmacodynamic model of Streptococcus pneumoniae naive and induced biofilms. J Antimicrob Chemother 2015; 70:1713-26. [PMID: 25712316 DOI: 10.1093/jac/dkv032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 01/21/2015] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVES Bacterial biofilms developing in the bronchial tree of patients experiencing acute exacerbations of chronic bronchitis (AECBs) are suggested to cause relapses and recurrences of the disease because the matrix barrier impairs antibiotic access to the offending organisms. We examined whether bronchodilators could modulate pneumococcal biofilm development and antibiotic action using an in vitro model. METHODS Streptococcus pneumoniae strains from patients hospitalized for AECBs and two reference strains (ATCC 49619 and R6) were screened for biofilm formation (multi-well plates; 2-11 days of growth). Ipratropium and salbutamol (alone or in combination) were added at concentrations of 1.45 and 7.25 mg/L, respectively (mimicking those in the bronchial tree), and their effects were measured on biofilm formation and modulation of the activity of antibiotics [full antibiotic concentration-dependent effects (pharmacodynamic model)] with a focus on moxifloxacin and solithromycin. Bacterial viability and biomass were measured by the reduction of resazurin and crystal violet staining, respectively. Release of sialic acid (from biofilm) and neuraminidase activity were measured using enzymatic and HPLC-MS detection of sialic acid. RESULTS All clinical isolates produced biofilms, but with fast disassembly if from patients who had received muscarinic antagonists. Ipratropium caused: (i) reduced biomass formation and faster biofilm disassembly with free sialic acid release; and (ii) a marked improvement of antibiotic activity (bacterial killing and biomass reduction). Salbutamol stimulated neuraminidase activity associated with improved antibiotic killing activity (reversed by zanamivir) but modest biomass reduction. CONCLUSIONS Ipratropium and, to a lesser extent, salbutamol may cooperate with antibiotics for bacterial clearance and disassembly of pneumococcal biofilms.
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Affiliation(s)
- Nathalie M Vandevelde
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Paul M Tulkens
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Giulio G Muccioli
- Bioanalysis and Pharmacology of Bioactive Lipids, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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Chao Y, Marks LR, Pettigrew MM, Hakansson AP. Streptococcus pneumoniae biofilm formation and dispersion during colonization and disease. Front Cell Infect Microbiol 2015; 4:194. [PMID: 25629011 PMCID: PMC4292784 DOI: 10.3389/fcimb.2014.00194] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/24/2014] [Indexed: 02/06/2023] Open
Abstract
Streptococcus pneumoniae (the pneumococcus) is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization results in millions of infections and over one million deaths per year, mostly in individuals under the age of 5 and the elderly. Colonizing pneumococci form well-organized biofilm communities in the nasopharyngeal environment, but the specific role of biofilms and their interaction with the host during colonization and disease is not yet clear. Pneumococci in biofilms are highly resistant to antimicrobial agents and this phenotype can be recapitulated when pneumococci are grown on respiratory epithelial cells under conditions found in the nasopharyngeal environment. Pneumococcal biofilms display lower levels of virulence in vivo and provide an optimal environment for increased genetic exchange both in vitro and in vivo, with increased natural transformation seen during co-colonization with multiple strains. Biofilms have also been detected on mucosal surfaces during pneumonia and middle ear infection, although the role of these biofilms in the disease process is debated. Recent studies have shown that changes in the nasopharyngeal environment caused by concomitant virus infection, changes in the microflora, inflammation, or other host assaults trigger active release of pneumococci from biofilms. These dispersed bacteria have distinct phenotypic properties and transcriptional profiles different from both biofilm and broth-grown, planktonic bacteria, resulting in a significantly increased virulence in vivo. In this review we discuss the properties of pneumococcal biofilms, the role of biofilm formation during pneumococcal colonization, including their propensity for increased ability to exchange genetic material, as well as mechanisms involved in transition from asymptomatic biofilm colonization to dissemination and disease of otherwise sterile sites. Greater understanding of pneumococcal biofilm formation and dispersion will elucidate novel avenues to interfere with the spread of antibiotic resistance and vaccine escape, as well as novel strategies to target the mechanisms involved in induction of pneumococcal disease.
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Affiliation(s)
- Yashuan Chao
- Division of Experimental Infection Medicine, Department of Laboratory Medicine, Lund UniversityMalmö, Sweden
| | - Laura R. Marks
- Department of Microbiology and Immunology, University at Buffalo, The State University of New YorkBuffalo, NY, USA
| | - Melinda M. Pettigrew
- Department of Epidemiology and Microbial Diseases, Yale School of Public HealthNew Haven, CT, USA
| | - Anders P. Hakansson
- Division of Experimental Infection Medicine, Department of Laboratory Medicine, Lund UniversityMalmö, Sweden
- Department of Microbiology and Immunology, University at Buffalo, The State University of New YorkBuffalo, NY, USA
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Gilley RP, Orihuela CJ. Pneumococci in biofilms are non-invasive: implications on nasopharyngeal colonization. Front Cell Infect Microbiol 2014; 4:163. [PMID: 25414838 PMCID: PMC4222220 DOI: 10.3389/fcimb.2014.00163] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 10/21/2014] [Indexed: 11/21/2022] Open
Abstract
Streptococcus pneumoniae (the pneumococcus) is an opportunistic pathogen that colonizes the human nasopharynx asymptomatically. Invasive pneumococcal disease develops following bacterial aspiration into the lungs. Pneumococci within the nasopharynx exist as biofilms, a growth phenotype characterized by surface attachment, encasement within an extracellular matrix, and antimicrobial resistance. Experimental evidence indicates that biofilm pneumococci are attenuated vs. their planktonic counterpart. Biofilm pneumococci failed to cause invasive disease in experimentally challenged mice and in vitro were shown to be non-invasive despite being hyper-adhesive. This attenuated phenotype corresponds with observations that biofilm pneumococci elicit significantly less cytokine and chemokine production from host cells than their planktonic counterparts. Microarray and proteomic studies show that pneumococci within biofilms have decreased metabolism, less capsular polysaccharide, and reduced production of the pore-forming toxin pneumolysin. Biofilm pneumococci are predominately in the transparent phenotype, which has elevated cell wall phosphorylcholine, an adhesin subject to C-reactive protein mediated opsonization. Herein, we review these changes in virulence, interpret their impact on colonization and transmission, and discuss the notion that non-invasive biofilms are principal lifestyle of S. pneumoniae.
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Affiliation(s)
- Ryan P Gilley
- Department of Microbiology and Immunology, Center for Airway Inflammation Research, The University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Carlos J Orihuela
- Department of Microbiology and Immunology, Center for Airway Inflammation Research, The University of Texas Health Science Center at San Antonio San Antonio, TX, USA
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Basu Roy A, Sauer K. Diguanylate cyclase NicD-based signalling mechanism of nutrient-induced dispersion by Pseudomonas aeruginosa. Mol Microbiol 2014; 94:771-93. [PMID: 25243483 DOI: 10.1111/mmi.12802] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2014] [Indexed: 01/15/2023]
Abstract
Dispersion enables the transition from the biofilm to the planktonic growth state in response to various cues. While several Pseudomonas aeruginosa proteins, including BdlA and the c-di-GMP phosphodiesterases DipA, RbdA, and NbdA, have been shown to be required for dispersion to occur, little is known about dispersion cue sensing and the signalling translating these cues into the modulation c-di-GMP levels to enable dispersion. Using glutamate-induced dispersion as a model, we report that dispersion-inducing nutrient cues are sensed via an outside-in signalling mechanism by the diguanylate cyclase NicD belonging to a family of seven transmembrane (7TM) receptors. NicD directly interacts with BdlA and the phosphodiesterase DipA, with NicD, BdlA, and DipA being part of the same pathway required for dispersion. Glutamate sensing by NicD results in NicD dephosphorylation and increased cyclase activity. Active NicD contributes to the non-processive proteolysis and activation of BdlA via phosphorylation and temporarily elevated c-di-GMP levels. BdlA, in turn, activates DipA, resulting in the overall reduction of c-di-GMP levels. Our results provide a basis for understanding the signalling mechanism based on NicD to induce biofilm dispersion that may be applicable to various biofilm-forming species and may have implications for the control of biofilm-related infections.
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Affiliation(s)
- Ankita Basu Roy
- Department of Biological Sciences, Binghamton University, 85 Murray Hill Road, Binghamton, NY, 13902, USA
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Pimentel de Araujo F, D'Ambrosio F, Camilli R, Fiscarelli E, Di Bonaventura G, Baldassarri L, Visca P, Pantosti A, Gherardi G. Characterization of Streptococcus pneumoniae clones from paediatric patients with cystic fibrosis. J Med Microbiol 2014; 63:1704-1715. [PMID: 25301526 DOI: 10.1099/jmm.0.072199-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The role of Streptococcus pneumoniae in cystic fibrosis (CF) is poorly understood. The pneumococcal population has changed over time after the introduction of the heptavalent conjugate vaccine (PCV7) and, more recently, the 13-valent conjugate vaccine (PCV13). Although serotypes and clones causing invasive pneumococcal disease or colonizing healthy children have been extensively analysed, little is known so far on the serotypes and clones of pneumococci in CF patients. The aim of this work was to investigate serotypes, antibiotic susceptibilities, genotypes and biofilm production of CF pneumococcal isolates. Overall, 44 S. pneumoniae strains collected from 32 paediatric CF patients from January 2010 to May 2012 in a large Italian CF Centre were tested for antimicrobial susceptibility testing by Etest, serotyped by the Quellung reaction and genotyped by a combination of different molecular typing methods, including pbp gene restriction profiling, pspA restriction profiling and sequencing, PFGE and multilocus sequence typing. Biofilm production by pneumococcal strains was also assessed. Penicillin non-susceptibility was 16 %. High resistance rates (>56 %) were observed for erythromycin, clindamycin and tetracycline. The most frequent serotype recovered was serotype 3 (31.8 %). The coverage of PCV7 and PCV13 was 6.8 and 47.7 %, respectively. More than 80 % of CF strains belonged to Pneumococcal Molecular Epidemiology Network (PMEN) reference clones, the most common being Netherlands(3)-ST180 (28.2 %), and Greece(21)-30/ST193 (15.4 %). All strains produced biofilm in vitro, although with large variability in biofilm formation efficiency. No correlation was found between biofilm levels and serotype, clone or antibiotic resistance. The high isolation rate of antibiotic-resistant serotype 3 pneumococci from CF patients suggests that PCV13 could increase protection from pneumococcal colonization and infection.
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Affiliation(s)
- Fernanda Pimentel de Araujo
- Integrated Research Centre (CIR), University Campus Biomedico, Via Alvaro del Portillo 200, 00128 Rome, Italy
| | - Fabio D'Ambrosio
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Romina Camilli
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Ersilia Fiscarelli
- Cystic Fibrosis Microbiology, Children's Hospital and Research Institute 'Bambino Gesù', Piazza S. Onofrio 4, 00165 Rome, Italy
| | - Giovanni Di Bonaventura
- Center of Excellence on Aging, 'G. D'Annunzio' University Foundation, Via Colle dell'Ara, 66100 Chieti, Italy.,Department of Experimental and Clinical Sciences, 'G. D'Annunzio' University of Chieti-Pescara, Via Vestini 31, 66100 Chieti, Italy
| | - Lucilla Baldassarri
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Paolo Visca
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy
| | - Annalisa Pantosti
- Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Giovanni Gherardi
- Integrated Research Centre (CIR), University Campus Biomedico, Via Alvaro del Portillo 200, 00128 Rome, Italy
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The fatty acid signaling molecule cis-2-decenoic acid increases metabolic activity and reverts persister cells to an antimicrobial-susceptible state. Appl Environ Microbiol 2014; 80:6976-91. [PMID: 25192989 DOI: 10.1128/aem.01576-14] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Persister cells, which are tolerant to antimicrobials, contribute to biofilm recalcitrance to therapeutic agents. In turn, the ability to kill persister cells is believed to significantly improve efforts in eradicating biofilm-related, chronic infections. While much research has focused on elucidating the mechanism(s) by which persister cells form, little is known about the mechanism or factors that enable persister cells to revert to an active and susceptible state. Here, we demonstrate that cis-2-decenoic acid (cis-DA), a fatty acid signaling molecule, is able to change the status of Pseudomonas aeruginosa and Escherichia coli persister cells from a dormant to a metabolically active state without an increase in cell number. This cell awakening is supported by an increase of the persister cells' respiratory activity together with changes in protein abundance and increases of the transcript expression levels of several metabolic markers, including acpP, 16S rRNA, atpH, and ppx. Given that most antimicrobials target actively growing cells, we also explored the effect of cis-DA on enhancing antibiotic efficacy in killing persister cells due to their inability to keep a persister cell state. Compared to antimicrobial treatment alone, combinational treatments of persister cell subpopulations with antimicrobials and cis-DA resulted in a significantly greater decrease in cell viability. In addition, the presence of cis-DA led to a decrease in the number of persister cells isolated. We thus demonstrate the ability of a fatty acid signaling molecule to revert bacterial cells from a tolerant phenotype to a metabolically active, antimicrobial-sensitive state.
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Allan RN, Skipp P, Jefferies J, Clarke SC, Faust SN, Hall-Stoodley L, Webb J. Pronounced metabolic changes in adaptation to biofilm growth by Streptococcus pneumoniae. PLoS One 2014; 9:e107015. [PMID: 25188255 PMCID: PMC4154835 DOI: 10.1371/journal.pone.0107015] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 08/05/2014] [Indexed: 11/19/2022] Open
Abstract
Streptococcus pneumoniae accounts for a significant global burden of morbidity and mortality and biofilm development is increasingly recognised as important for colonization and infection. Analysis of protein expression patterns during biofilm development may therefore provide valuable insights to the understanding of pneumococcal persistence strategies and to improve vaccines. iTRAQ (isobaric tagging for relative and absolute quantification), a high-throughput gel-free proteomic approach which allows high resolution quantitative comparisons of protein profiles between multiple phenotypes, was used to interrogate planktonic and biofilm growth in a clinical serotype 14 strain. Comparative analyses of protein expression between log-phase planktonic and 1-day and 7-day biofilm cultures representing nascent and late phase biofilm growth were carried out. Overall, 244 proteins were identified, of which >80% were differentially expressed during biofilm development. Quantitatively and qualitatively, metabolic regulation appeared to play a central role in the adaptation from the planktonic to biofilm phenotype. Pneumococci adapted to biofilm growth by decreasing enzymes involved in the glycolytic pathway, as well as proteins involved in translation, transcription, and virulence. In contrast, proteins with a role in pyruvate, carbohydrate, and arginine metabolism were significantly increased during biofilm development. Downregulation of glycolytic and translational proteins suggests that pneumococcus adopts a covert phenotype whilst adapting to an adherent lifestyle, while utilization of alternative metabolic pathways highlights the resourcefulness of pneumococcus to facilitate survival in diverse environmental conditions. These metabolic proteins, conserved across both the planktonic and biofilm phenotypes, may also represent target candidates for future vaccine development and treatment strategies. Data are available via ProteomeXchange with identifier PXD001182.
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Affiliation(s)
- Raymond N. Allan
- Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- * E-mail:
| | - Paul Skipp
- Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom
- Centre for Proteomic Research, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Johanna Jefferies
- Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- Public Health England, Southampton, United Kingdom
| | - Stuart C. Clarke
- Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- Public Health England, Southampton, United Kingdom
- Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Saul N. Faust
- Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Luanne Hall-Stoodley
- Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- Southampton NIHR Wellcome Trust Clinical Research Facility, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- Microbial Infection and Immunity, Centre for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Jeremy Webb
- Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom
- Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
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Dynamic changes in the Streptococcus pneumoniae transcriptome during transition from biofilm formation to invasive disease upon influenza A virus infection. Infect Immun 2014; 82:4607-19. [PMID: 25135685 DOI: 10.1128/iai.02225-14] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is a leading cause of infectious disease globally. Nasopharyngeal colonization occurs in biofilms and precedes infection. Prior studies have indicated that biofilm-derived pneumococci are avirulent. However, influenza A virus (IAV) infection releases virulent pneumococci from biofilms in vitro and in vivo. Triggers of dispersal include IAV-induced changes in the nasopharynx, such as increased temperature (fever) and extracellular ATP (tissue damage). We used whole-transcriptome shotgun sequencing (RNA-seq) to compare the S. pneumoniae transcriptome in biofilms, bacteria dispersed from biofilms after exposure to IAV, febrile-range temperature, or ATP, and planktonic cells grown at 37°C. Compared with biofilm bacteria, actively dispersed S. pneumoniae, which were more virulent in invasive disease, upregulated genes involved in carbohydrate metabolism. Enzymatic assays for ATP and lactate production confirmed that dispersed pneumococci exhibited increased metabolism compared to those in biofilms. Dispersed pneumococci also upregulated genes associated with production of bacteriocins and downregulated colonization-associated genes related to competence, fratricide, and the transparent colony phenotype. IAV had the largest impact on the pneumococcal transcriptome. Similar transcriptional differences were also observed when actively dispersed bacteria were compared with avirulent planktonic bacteria. Our data demonstrate complex changes in the pneumococcal transcriptome in response to IAV-induced changes in the environment. Our data suggest that disease is caused by pneumococci that are primed to move to tissue sites with altered nutrient availability and to protect themselves from the nasopharyngeal microflora and host immune response. These data help explain pneumococcal virulence after IAV infection and have important implications for studies of S. pneumoniae pathogenesis.
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Wu S, Baum MM, Kerwin J, Guerrero D, Webster S, Schaudinn C, VanderVelde D, Webster P. Biofilm-specific extracellular matrix proteins of nontypeable Haemophilus influenzae. Pathog Dis 2014; 72:143-60. [PMID: 24942343 DOI: 10.1111/2049-632x.12195] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/07/2014] [Accepted: 06/11/2014] [Indexed: 11/28/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi), a human respiratory tract pathogen, can form colony biofilms in vitro. Bacterial cells and the amorphous extracellular matrix (ECM) constituting the biofilm can be separated using sonication. The ECM from 24- and 96-h NTHi biofilms contained polysaccharides and proteinaceous components as detected by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) spectroscopy. More conventional chemical assays on the biofilm ECM confirmed the presence of these components and also DNA. Proteomics revealed eighteen proteins present in biofilm ECM that were not detected in planktonic bacteria. One ECM protein was unique to 24-h biofilms, two were found only in 96-h biofilms, and fifteen were present in the ECM of both 24- and 96-h NTHi biofilms. All proteins identified were either associated with bacterial membranes or cytoplasmic proteins. Immunocytochemistry showed two of the identified proteins, a DNA-directed RNA polymerase and the outer membrane protein OMP P2, associated with bacteria and biofilm ECM. Identification of biofilm-specific proteins present in immature biofilms is an important step in understanding the in vitro process of NTHi biofilm formation. The presence of a cytoplasmic protein and a membrane protein in the biofilm ECM of immature NTHi biofilms suggests that bacterial cell lysis may be a feature of early biofilm formation.
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Affiliation(s)
- Siva Wu
- Bioenergy/GTL & Structural Biology Department, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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Antibiotic activity against naive and induced Streptococcus pneumoniae biofilms in an in vitro pharmacodynamic model. Antimicrob Agents Chemother 2013; 58:1348-58. [PMID: 24342635 DOI: 10.1128/aac.01858-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Biofilms play a role in the pathogenicity of pneumococcal infections. A pharmacodynamic in vitro model of biofilm was developed that allows characterization of the activity of antibiotics against viability and biomass by using in parallel capsulated (ATCC 49619) and noncapsulated (R6) reference strains. Naive biofilms were obtained by incubating fresh planktonic cultures for 2 to 11 days in 96-well polystyrene plates. Induced biofilms were obtained using planktonic bacteria collected from the supernatant of 6-day-old naive biofilms. Biomass production was more rapid and intense in the induced model, but the levels were similar for both strains. Full concentration responses fitting sigmoidal regressions allowed calculation of maximal efficacies and relative potencies of drugs. All antibiotics tested (amoxicillin, clarithromycin, solithromycin, levofloxacin, and moxifloxacin) were more effective against young naive biofilms than against old or induced biofilms, except macrolides/ketolides, which were as effective at reducing viability in 2-day-old naive biofilms and in 11-day-old induced biofilms of R6. Macrolides/ketolides, however, were less potent than fluoroquinolones against R6 (approximately 5- to 20-fold-higher concentrations needed to reduction viability of 20%). However, at concentrations obtainable in epithelial lining fluid, the viabilities of mature or induced biofilms were reduced 15 to 45% (amoxicillin), 17 to 44% (macrolides/ketolides), and 12 to 64% (fluoroquinolones), and biomasses were reduced 5 to 45% (amoxicillin), 5 to 60% (macrolides/ketolides), and 10 to 76% (fluoroquinolones), with solithromycin and moxifloxacin being the most effective and the most potent agents (due to lower MICs) in their respective classes. This study allowed the ranking of antibiotics with respect to their potential effectiveness in biofilm-related infections, underlining the need to search for still more effective options.
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Novel role for the Streptococcus pneumoniae toxin pneumolysin in the assembly of biofilms. mBio 2013. [PMID: 24023386 DOI: 10.1128/mbio.00655-13.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Streptococcus pneumoniae is an important commensal and pathogen responsible for almost a million deaths annually in children under five. The formation of biofilms by S. pneumoniae is important in nasopharyngeal colonization, pneumonia, and otitis media. Pneumolysin (Ply) is a toxin that contributes significantly to the virulence of S. pneumoniae and is an important candidate as a serotype-independent vaccine target. Having previously demonstrated that a luxS knockout mutant was unable to form early biofilms and expressed less ply mRNA than the wild type, we conducted a study to investigate the role of Ply in biofilm formation. We found that Ply was expressed in early phases of biofilm development and localized to cellular aggregates as early as 4 h postinoculation. S. pneumoniae ply knockout mutants in D39 and TIGR4 backgrounds produced significantly less biofilm biomass than wild-type strains at early time points, both on polystyrene and on human respiratory epithelial cells, cultured under static or continuous-flow conditions. Ply's role in biofilm formation appears to be independent of its hemolytic activity, as S. pneumoniae serotype 1 strains, which produce a nonhemolytic variant of Ply, were still able to form biofilms. Transmission electron microscopy of biofilms grown on A549 lung cells using immunogold demonstrated that Ply was located both on the surfaces of pneumococcal cells and in the extracellular biofilm matrix. Altogether, our studies demonstrate a novel role for pneumolysin in the assembly of S. pneumoniae biofilms that is likely important during both carriage and disease and therefore significant for pneumolysin-targeting vaccines under development. IMPORTANCE The bacterium Streptococcus pneumoniae (commonly known as the pneumococcus) is commonly carried in the human nasopharynx and can spread to other body sites to cause disease. In the nasopharynx, middle ear, and lungs, the pneumococcus forms multicellular surface-associated structures called biofilms. Pneumolysin is an important toxin produced by almost all S. pneumoniae strains, extensively studied for its ability to cause damage to human tissue. In this paper, we demonstrate that pneumolysin has a previously unrecognized role in biofilm formation by showing that strains without pneumolysin are unable to form the same amount of biofilm on plastic and human cell substrates. Furthermore, we show that the role of pneumolysin in biofilm formation is separate from the hemolytic activity responsible for tissue damage during pneumococcal diseases. This novel role for pneumolysin suggests that pneumococcal vaccines directed against this protein should be investigated for their potential impact on biofilms formed during carriage and disease.
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Abstract
Streptococcus pneumoniae is an important commensal and pathogen responsible for almost a million deaths annually in children under five. The formation of biofilms by S. pneumoniae is important in nasopharyngeal colonization, pneumonia, and otitis media. Pneumolysin (Ply) is a toxin that contributes significantly to the virulence of S. pneumoniae and is an important candidate as a serotype-independent vaccine target. Having previously demonstrated that a luxS knockout mutant was unable to form early biofilms and expressed less ply mRNA than the wild type, we conducted a study to investigate the role of Ply in biofilm formation. We found that Ply was expressed in early phases of biofilm development and localized to cellular aggregates as early as 4 h postinoculation. S. pneumoniae ply knockout mutants in D39 and TIGR4 backgrounds produced significantly less biofilm biomass than wild-type strains at early time points, both on polystyrene and on human respiratory epithelial cells, cultured under static or continuous-flow conditions. Ply’s role in biofilm formation appears to be independent of its hemolytic activity, as S. pneumoniae serotype 1 strains, which produce a nonhemolytic variant of Ply, were still able to form biofilms. Transmission electron microscopy of biofilms grown on A549 lung cells using immunogold demonstrated that Ply was located both on the surfaces of pneumococcal cells and in the extracellular biofilm matrix. Altogether, our studies demonstrate a novel role for pneumolysin in the assembly of S. pneumoniae biofilms that is likely important during both carriage and disease and therefore significant for pneumolysin-targeting vaccines under development. The bacterium Streptococcus pneumoniae (commonly known as the pneumococcus) is commonly carried in the human nasopharynx and can spread to other body sites to cause disease. In the nasopharynx, middle ear, and lungs, the pneumococcus forms multicellular surface-associated structures called biofilms. Pneumolysin is an important toxin produced by almost all S. pneumoniae strains, extensively studied for its ability to cause damage to human tissue. In this paper, we demonstrate that pneumolysin has a previously unrecognized role in biofilm formation by showing that strains without pneumolysin are unable to form the same amount of biofilm on plastic and human cell substrates. Furthermore, we show that the role of pneumolysin in biofilm formation is separate from the hemolytic activity responsible for tissue damage during pneumococcal diseases. This novel role for pneumolysin suggests that pneumococcal vaccines directed against this protein should be investigated for their potential impact on biofilms formed during carriage and disease.
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Karim MM, Hisamoto T, Matsunaga T, Asahi Y, Noiri Y, Ebisu S, Kato A, Azakami H. LuxS affects biofilm maturation and detachment of the periodontopathogenic bacterium Eikenella corrodens. J Biosci Bioeng 2013; 116:313-8. [DOI: 10.1016/j.jbiosc.2013.03.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 03/08/2013] [Accepted: 03/19/2013] [Indexed: 01/25/2023]
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Antimicrobial tolerance of Pseudomonas aeruginosa biofilms is activated during an early developmental stage and requires the two-component hybrid SagS. J Bacteriol 2013; 195:4975-87. [PMID: 23995639 DOI: 10.1128/jb.00732-13] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A hallmark characteristic of biofilms is their extraordinary tolerance to antimicrobial agents. While multiple factors are thought to contribute to the high level of antimicrobial tolerance of biofilms, little is known about the timing of induction of biofilm tolerance. Here, we asked when over the course of their development do biofilms gain their tolerance to antimicrobial agents? We demonstrate that in Pseudomonas aeruginosa, biofilm tolerance is linked to biofilm development, with transition to the irreversible attachment stage regulated by the two-component hybrid SagS, marking the timing when biofilms switch to the high-level tolerance phenotype. Inactivation of sagS rendered biofilms but not planktonic cells more susceptible to tobramycin, norfloxacin, and hydrogen peroxide. Moreover, inactivation of sagS also eliminated the recalcitrance of biofilms to killing by bactericidal antimicrobial agents, a phenotype comparable to that observed upon inactivation of brlR, which encodes a MerR-like transcriptional regulator required for biofilm tolerance. Multicopy expression of brlR in a ΔsagS mutant restored biofilm resistance and recalcitrance to killing by bactericidal antibiotics to wild-type levels. In contrast, expression of sagS did not restore the susceptibility phenotype of ΔbrlR mutant biofilms to wild-type levels, indicating that BrlR functions downstream of SagS. Inactivation of sagS correlated with reduced BrlR levels in biofilms, with the produced BrlR being impaired in binding to the previously described BrlR-activated promoters of the two multidrug efflux pump operons mexAB-oprM and mexEF-oprN. Our findings demonstrate that biofilm tolerance is linked to early biofilm development and SagS, with SagS contributing indirectly to BrlR activation.
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Zimaro T, Thomas L, Marondedze C, Garavaglia BS, Gehring C, Ottado J, Gottig N. Insights into xanthomonas axonopodis pv. citri biofilm through proteomics. BMC Microbiol 2013; 13:186. [PMID: 23924281 PMCID: PMC3750573 DOI: 10.1186/1471-2180-13-186] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 08/02/2013] [Indexed: 11/28/2022] Open
Abstract
Background Xanthomonas axonopodis pv. citri (X. a. pv. citri) causes citrus canker that can result in defoliation and premature fruit drop with significant production losses worldwide. Biofilm formation is an important process in bacterial pathogens and several lines of evidence suggest that in X. a. pv. citri this process is a requirement to achieve maximal virulence since it has a major role in host interactions. In this study, proteomics was used to gain further insights into the functions of biofilms. Results In order to identify differentially expressed proteins, a comparative proteomic study using 2D difference gel electrophoresis was carried out on X. a. pv. citri mature biofilm and planktonic cells. The biofilm proteome showed major variations in the composition of outer membrane proteins and receptor or transport proteins. Among them, several porins and TonB-dependent receptor were differentially regulated in the biofilm compared to the planktonic cells, indicating that these proteins may serve in maintaining specific membrane-associated functions including signaling and cellular homeostasis. In biofilms, UDP-glucose dehydrogenase with a major role in exopolysaccharide production and the non-fimbrial adhesin YapH involved in adherence were over-expressed, while a polynucleotide phosphorylase that was demonstrated to negatively control biofilm formation in E. coli was down-regulated. In addition, several proteins involved in protein synthesis, folding and stabilization were up-regulated in biofilms. Interestingly, some proteins related to energy production, such as ATP-synthase were down-regulated in biofilms. Moreover, a number of enzymes of the tricarboxylic acid cycle were differentially expressed. In addition, X. a. pv. citri biofilms also showed down-regulation of several antioxidant enzymes. The respective gene expression patterns of several identified proteins in both X. a. pv. citri mature biofilm and planktonic cells were evaluated by quantitative real-time PCR and shown to consistently correlate with those deduced from the proteomic study. Conclusions Differentially expressed proteins are enriched in functional categories. Firstly, proteins that are down-regulated in X. a. pv. citri biofilms are enriched for the gene ontology (GO) terms ‘generation of precursor metabolites and energy’ and secondly, the biofilm proteome mainly changes in ‘outer membrane and receptor or transport’. We argue that the differentially expressed proteins have a critical role in maintaining a functional external structure as well as enabling appropriate flow of nutrients and signals specific to the biofilm lifestyle.
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Affiliation(s)
- Tamara Zimaro
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (IBR-CONICET), Ocampo y Esmeralda, Rosario, Santa Fe, Argentina
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Interkingdom signaling induces Streptococcus pneumoniae biofilm dispersion and transition from asymptomatic colonization to disease. mBio 2013; 4:mBio.00438-13. [PMID: 23882016 PMCID: PMC3735180 DOI: 10.1128/mbio.00438-13] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Streptococcus pneumoniae is a common human nasopharyngeal commensal colonizing 10% to 40% of healthy individuals, depending on age. Despite a low invasive disease rate, widespread carriage ensures that infection occurs often enough to make S. pneumoniae a leading bacterial cause of respiratory disease worldwide. However, the mechanisms behind transition from asymptomatic colonization to dissemination and disease in otherwise sterile sites remain poorly understood but are epidemiologically strongly linked to infection with respiratory viruses. In this report, we show that infection with influenza A virus and treatment with the resulting host signals (febrile-range temperatures, norepinephrine, extracytoplasmic ATP, and increased nutrient availability) induce the release of bacteria from biofilms in a newly developed biofilm model on live epithelial cells both in vitro and during in vivo colonization. These dispersed bacteria have distinct phenotypic properties different from those of both biofilm and broth-grown, planktonic bacteria, with the dispersed population showing differential virulence gene expression characteristics resulting in a significantly increased ability to disseminate and cause infection of otherwise sterile sites, such as the middle ear, lungs, and bloodstream. The results offer novel and important insights into the role of interkingdom signaling between microbe and host during biofilm dispersion and transition to acute disease. This report addresses the mechanisms involved in transition from pneumococcal asymptomatic colonization to disease. In this study, we determined that changes in the nasopharyngeal environment result in the release of bacteria from colonizing biofilms with a gene expression and virulence phenotype different not only from that of colonizing biofilm bacteria but also from that of the broth-grown planktonic bacteria commonly used for pathogenesis studies. The work importantly also identifies specific host factors responsible for the release of bacteria and their changed phenotype. We show that these interkingdom signals are recognized by bacteria and are induced by influenza virus infection, which is epidemiologically strongly associated with transition to secondary pneumococcal disease. As virus infection is a common inducer of transition to disease among species occupying the nasopharynx, the results of this study may provide a basis for better understanding of the signals involved in the transition from colonization to disease in the human nasopharynx.
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Biofilm formation avoids complement immunity and phagocytosis of Streptococcus pneumoniae. Infect Immun 2013; 81:2606-15. [PMID: 23649097 DOI: 10.1128/iai.00491-13] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Streptococcus pneumoniae is a frequent member of the microbiota of the human nasopharynx. Colonization of the nasopharyngeal tract is a first and necessary step in the infectious process and often involves the formation of sessile microbial communities by this human pathogen. The ability to grow and persist as biofilms is an advantage for many microorganisms, because biofilm-grown bacteria show reduced susceptibility to antimicrobial agents and hinder recognition by the immune system. The extent of host protection against biofilm-related pneumococcal disease has not been determined yet. Using pneumococcal strains growing as planktonic cultures or as biofilms, we have investigated the recognition of S. pneumoniae by the complement system and its interactions with human neutrophils. Deposition of C3b, the key complement component, was impaired on S. pneumoniae biofilms. In addition, binding of C-reactive protein and the complement component C1q to the pneumococcal surface was reduced in biofilm bacteria, demonstrating that pneumococcal biofilms avoid the activation of the classical complement pathway. In addition, recruitment of factor H, the downregulator of the alternative pathway, was enhanced by S. pneumoniae growing as biofilms. Our results also show that biofilm formation diverts the alternative complement pathway activation by a PspC-mediated mechanism. Furthermore, phagocytosis of pneumococcal biofilms was also impaired. The present study confirms that biofilm formation in S. pneumoniae is an efficient means of evading both the classical and the PspC-dependent alternative complement pathways the host immune system.
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