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Mårli MT, Oppegaard O, Porcellato D, Straume D, Kjos M. Genetic modification of Streptococcus dysgalactiae by natural transformation. mSphere 2024; 9:e0021424. [PMID: 38904369 PMCID: PMC11288034 DOI: 10.1128/msphere.00214-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/13/2024] [Indexed: 06/22/2024] Open
Abstract
Streptococcus dysgalactiae is an emerging human and animal pathogen. Functional studies of genes involved in virulence of S. dysgalactiae and other pyogenic group streptococci are often hampered by limited genetic tractability. It is known that pyogenic streptococci carry genes required for competence for natural transformation; however, in contrast to other streptococcal subgroups, there is limited evidence for gene transfer by natural transformation in these bacteria. In this study, we systematically assessed the genomes of 179 S. dysgalactiae strains of both human and animal origins (subsp. equisimilis and dysgalactiae, respectively) for the presence of genes required for natural transformation. While a considerable fraction of the strains contained inactive genes, the majority (64.2%) of the strains had an intact gene set. In selected strains, we examined the dynamics of competence activation after addition of competence-inducing pheromones using transcriptional reporter assays and exploratory RNA-seq. Based on these findings, we were able to establish a protocol allowing us to utilize natural transformation to construct deletion mutants by allelic exchange in several S. dysgalactiae strains of both subspecies. As part of the work, we deleted putative lactose utilization genes to study their role in growth on lactose. The data presented here provide new knowledge on the potential of horizonal gene transfer by natural transformation in S. dysgalactiae and, importantly, demonstrates the possibility to exploit natural transformation for genetic engineering in these bacteria. IMPORTANCE Numerous Streptococcus spp. exchange genes horizontally through natural transformation, which also facilitates efficient genetic engineering in these organisms. However, for the pyogenic group of streptococci, including the emerging pathogen Streptococcus dysgalactiae, there is limited experimental evidence for natural transformation. In this study, we demonstrate that natural transformation in vitro indeed is possible in S. dysgalactiae strains under optimal conditions. We utilized this method to perform gene deletion through allelic exchange in several strains, thereby paving the way for more efficient gene engineering methods in pyogenic streptococci.
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Affiliation(s)
- Marita Torrissen Mårli
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Oddvar Oppegaard
- Haukeland University Hospital, University of Bergen, Bergen, Norway
| | - Davide Porcellato
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Daniel Straume
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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2
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Prudhomme M, Johnston CHG, Soulet AL, Boyeldieu A, De Lemos D, Campo N, Polard P. Pneumococcal competence is a populational health sensor driving multilevel heterogeneity in response to antibiotics. Nat Commun 2024; 15:5625. [PMID: 38987237 PMCID: PMC11237056 DOI: 10.1038/s41467-024-49853-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 06/21/2024] [Indexed: 07/12/2024] Open
Abstract
Competence for natural transformation is a central driver of genetic diversity in bacteria. In the human pathogen Streptococcus pneumoniae, competence exhibits a populational character mediated by the stress-induced ComABCDE quorum-sensing (QS) system. Here, we explore how this cell-to-cell communication mechanism proceeds and the functional properties acquired by competent cells grown under lethal stress. We show that populational competence development depends on self-induced cells stochastically emerging in response to stresses, including antibiotics. Competence then propagates through the population from a low threshold density of self-induced cells, defining a biphasic Self-Induction and Propagation (SI&P) QS mechanism. We also reveal that a competent population displays either increased sensitivity or improved tolerance to lethal doses of antibiotics, dependent in the latter case on the competence-induced ComM division inhibitor. Remarkably, these surviving competent cells also display an altered transformation potential. Thus, the unveiled SI&P QS mechanism shapes pneumococcal competence as a health sensor of the clonal population, promoting a bet-hedging strategy that both responds to and drives cells towards heterogeneity.
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Affiliation(s)
- Marc Prudhomme
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France
- Université Paul Sabatier (Toulouse III), Toulouse, France
| | - Calum H G Johnston
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France
- Université Paul Sabatier (Toulouse III), Toulouse, France
| | - Anne-Lise Soulet
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France
- Université Paul Sabatier (Toulouse III), Toulouse, France
| | - Anne Boyeldieu
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France
- Université Paul Sabatier (Toulouse III), Toulouse, France
| | - David De Lemos
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France
- Université Paul Sabatier (Toulouse III), Toulouse, France
| | - Nathalie Campo
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France
- Université Paul Sabatier (Toulouse III), Toulouse, France
| | - Patrice Polard
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), UMR5100, Centre de Biologie Intégrative (CBI), Centre Nationale de la Recherche Scientifique (CNRS), Toulouse, France.
- Université Paul Sabatier (Toulouse III), Toulouse, France.
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Oh MW, Lin J, Chong SY, Lew SQ, Alam T, Lau GW. Time-resolved RNA-seq analysis to unravel the in vivo competence induction by Streptococcus pneumoniae during pneumonia-derived sepsis. Microbiol Spectr 2024; 12:e0305023. [PMID: 38305162 PMCID: PMC10913500 DOI: 10.1128/spectrum.03050-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 01/09/2024] [Indexed: 02/03/2024] Open
Abstract
Competence development in Streptococcus pneumoniae (pneumococcus) is tightly intertwined with virulence. In addition to genes encoding genetic transformation machinery, the competence regulon also regulates the expression of allolytic factors, bacteriocins, and cytotoxins. Pneumococcal competence system has been extensively interrogated in vitro where the short transient competent state upregulates the expression of three distinct phases of "early," "late," and "delayed" genes. Recently, we have demonstrated that the pneumococcal competent state develops naturally in mouse models of pneumonia-derived sepsis. To unravel the underlying adaptive mechanisms driving the development of the competent state, we conducted a time-resolved transcriptomic analysis guided by the spatiotemporal live in vivo imaging system of competence induction during pneumonia-derived sepsis. Mouse lungs infected by the serotype 2 strain D39 expressing a competent state-specific reporter gene (D39-ssbB-luc) were subjected to RNA sequencing guided by monitoring the competence development at 0, 12, 24, and, at the moribund state, >40 hours post-infection (hpi). Transcriptomic analysis revealed that the competence-specific gene expression patterns in vivo were distinct from those under in vitro conditions. There was significant upregulation of early, late, and some delayed phase competence-specific genes as early as 12 hpi, suggesting that the pneumococcal competence regulon is important for adaptation to the lung environment. Additionally, members of the histidine triad (pht) gene family were sharply upregulated at 12 hpi followed by a steep decline throughout the rest of the infection cycle, suggesting that Pht proteins participate in the early adaptation to the lung environment. Further analysis revealed that Pht proteins execute a metal ion-dependent regulatory role in competence induction.IMPORTANCEThe induction of pneumococcal competence for genetic transformation has been extensively studied in vitro but poorly understood during lung infection. We utilized a combination of live imaging and RNA sequencing to monitor the development of a competent state during acute pneumonia. Upregulation of competence-specific genes was observed as early as 12 hour post-infection, suggesting that the pneumococcal competence regulon plays an important role in adapting pneumococcus to the stressful lung environment. Among others, we report novel finding that the pneumococcal histidine triad (pht) family of genes participates in the adaptation to the lung environment and regulates pneumococcal competence induction.
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Affiliation(s)
- Myung Whan Oh
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Jingjun Lin
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Sook Yin Chong
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Shi Qian Lew
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Tauqeer Alam
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Gee W. Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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Echlin H, Iverson A, Sardo U, Rosch JW. Airway proteolytic control of pneumococcal competence. PLoS Pathog 2023; 19:e1011421. [PMID: 37256908 PMCID: PMC10259803 DOI: 10.1371/journal.ppat.1011421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 06/12/2023] [Accepted: 05/11/2023] [Indexed: 06/02/2023] Open
Abstract
Streptococcus pneumoniae is an opportunistic pathogen that colonizes the upper respiratory tract asymptomatically and, upon invasion, can lead to severe diseases including otitis media, sinusitis, meningitis, bacteremia, and pneumonia. One of the first lines of defense against pneumococcal invasive disease is inflammation, including the recruitment of neutrophils to the site of infection. The invasive pneumococcus can be cleared through the action of serine proteases generated by neutrophils. It is less clear how serine proteases impact non-invasive pneumococcal colonization, which is the key first step to invasion and transmission. One significant aspect of pneumococcal biology and adaptation in the respiratory tract is its natural competence, which is triggered by a small peptide CSP. In this study, we investigate if serine proteases are capable of degrading CSP and the impact this has on pneumococcal competence. We found that CSP has several potential sites for trypsin-like serine protease degradation and that there were preferential cleavage sites recognized by the proteases. Digestion of CSP with two different trypsin-like serine proteases dramatically reduced competence in a dose-dependent manner. Incubation of CSP with mouse lung homogenate also reduced recombination frequency of the pneumococcus. These ex vivo experiments suggested that serine proteases in the lower respiratory tract reduce pneumococcal competence. This was subsequently confirmed measuring in vivo recombination frequencies after induction of protease production via poly (I:C) stimulation and via co-infection with influenza A virus, which dramatically lowered recombination events. These data shed light on a new mechanism by which the host can modulate pneumococcal behavior and genetic exchange via direct degradation of the competence signaling peptide.
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Affiliation(s)
- Haley Echlin
- Department of Infectious Diseases, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Amy Iverson
- Department of Infectious Diseases, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Ugo Sardo
- Department of Infectious Diseases, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Jason W. Rosch
- Department of Infectious Diseases, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
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Antezana BS, Lohsen S, Wu X, Vidal JE, Tzeng YL, Stephens DS. Dissemination of Tn 916-Related Integrative and Conjugative Elements in Streptococcus pneumoniae Occurs by Transformation and Homologous Recombination in Nasopharyngeal Biofilms. Microbiol Spectr 2023; 11:e0375922. [PMID: 36912669 PMCID: PMC10101023 DOI: 10.1128/spectrum.03759-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 02/02/2023] [Indexed: 03/14/2023] Open
Abstract
Multidrug resistance in Streptococcus pneumoniae (or pneumococcus) continues to be a global challenge. An important class of antibiotic resistance determinants disseminating in S. pneumoniae are >20-kb Tn916-related integrative and conjugative elements (ICEs), such as Tn2009, Tn6002, and Tn2010. Although conjugation has been implicated as the transfer mechanism for ICEs in several bacteria, including S. pneumoniae, the molecular basis for widespread dissemination of pneumococcal Tn916-related ICEs remains to be fully elucidated. We found that Tn2009 acquisition was not detectable via in vitro transformation nor conjugative mating with donor GA16833, yielding a transfer frequency of <10-7. GA16833 Tn2009 conjugative gene expression was not significantly induced, and ICE circular intermediate formation was not detected in biofilms. Consistently, Tn2009 transfer efficiency in biofilms was not affected by deletion of the ICE conjugative gene ftsK. However, GA16833 Tn2009 transfer occurred efficiently at a recombination frequency (rF) of 10-4 in dual-strain biofilms formed in a human nasopharyngeal cell bioreactor. DNase I addition and deletions of the early competence gene comE or transformation apparatus genes comEA and comEC in the D39 recipient strain prevented Tn2009 acquisition (rF of <10-7). Genome sequencing and single nucleotide polymorphism analyses of independent recombinants of recipient genotype identified ~33- to ~55-kb donor DNAs containing intact Tn2009, supporting homologous recombination. Additional pneumococcal donor and recipient combinations were demonstrated to efficiently transfer Tn916-related ICEs at a rF of 10-4 in the biofilms. Tn916-related ICEs horizontally disseminate at high frequency in human nasopharyngeal S. pneumoniae biofilms by transformation and homologous recombination of >30-kb DNA fragments into the pneumococcal genome. IMPORTANCE The World Health Organization has designated Streptococcus pneumoniae as a priority pathogen for research and development of new drug treatments due to extensive multidrug resistance. Multiple strains of S. pneumoniae colonize and form mixed biofilms in the human nasopharynx, which could enable exchange of antibiotic resistance determinants. Tn916-related integrative and conjugative elements (ICEs) are largely responsible for the widespread presence of macrolide and tetracycline resistance in S. pneumoniae. Utilizing a system that simulates colonization of donor and recipient S. pneumoniae strains in the human nasopharynx, efficient transfer of Tn916-related ICEs occurred in human nasopharyngeal biofilms, in contrast to in vitro conditions of planktonic cells with exogenous DNA. This high-frequency Tn916-related ICE transfer between S. pneumoniae strains in biofilms was due to transformation and homologous recombination, not conjugation. Understanding the molecular mechanism for dissemination of Tn916-related ICEs can facilitate the design of new strategies to combat antibiotic resistance.
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Affiliation(s)
- Brenda S. Antezana
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Emory University Laney Graduate School, Atlanta, Georgia, USA
| | - Sarah Lohsen
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Xueqing Wu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, Zhejiang University College of Medicine, Hangzhou, China
| | - Jorge E. Vidal
- Department of Cell and Molecular Biology, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Yih-Ling Tzeng
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
| | - David S. Stephens
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
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6
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Kahlert CR, Nigg S, Onder L, Dijkman R, Diener L, Vidal AGJ, Rodriguez R, Vernazza P, Thiel V, Vidal JE, Albrich WC. The quorum sensing com system regulates pneumococcal colonisation and invasive disease in a pseudo-stratified airway tissue model. Microbiol Res 2023; 268:127297. [PMID: 36608536 PMCID: PMC9868095 DOI: 10.1016/j.micres.2022.127297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 01/01/2023]
Abstract
BACKGROUND The effects of the com quorum sensing system during colonisation and invasion of Streptococcus pneumoniae (Spn) are poorly understood. METHODS We developed an ex vivo model of differentiated human airway epithelial (HAE) cells with beating ciliae, mucus production and tight junctions to study Spn colonisation and translocation. HAE cells were inoculated with Spn wild-type TIGR4 (wtSpn) or its isogenic ΔcomC quorum sensing-deficient mutant. RESULTS Colonisation density of ΔcomC mutant was lower after 6 h but higher at 19 h and 30 h compared to wtSpn. Translocation correlated inversely with colonisation density. Transepithelial electric resistance (TEER) decreased after pneumococcal inoculation and correlated with increased translocation. Confocal imaging illustrated prominent microcolony formation with wtSpn but disintegration of microcolony structures with ΔcomC mutant. ΔcomC mutant showed greater cytotoxicity than wtSpn, suggesting that cytotoxicity was likely not the mechanism leading to translocation. There was greater density- and time-dependent increase of inflammatory cytokines including NLRP3 inflammasome-related IL-18 after infection with ΔcomC compared with wtSpn. ComC inactivation was associated with increased pneumolysin expression. CONCLUSIONS ComC system allows a higher organisational level of population structure resulting in microcolony formation, increased early colonisation and subsequent translocation. We propose that ComC inactivation unleashes a very different and possibly more virulent phenotype that merits further investigation.
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Affiliation(s)
- Christian R Kahlert
- Division of Infectious Diseases & Hospital Epidemiology, Cantonal Hospital St. Gallen, Switzerland; Children's Hospital of Eastern Switzerland, Infectious Disease & Hospital Epidemiology, St. Gallen, Switzerland.
| | - Susanne Nigg
- Division of Infectious Diseases & Hospital Epidemiology, Cantonal Hospital St. Gallen, Switzerland
| | - Lucas Onder
- Institute of Immunobiology, Cantonal Hospital St. Gallen, Switzerland
| | - Ronald Dijkman
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Liliane Diener
- Empa, Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland
| | - Ana G Jop Vidal
- Department of Cell and Molecular Biology, and Center for Immunology and Microbial Research, University of Mississippi Medical Center, Jackson, MS, USA
| | - Regulo Rodriguez
- Institute of Pathology, Cantonal Hospital St. Gallen, Switzerland
| | - Pietro Vernazza
- Division of Infectious Diseases & Hospital Epidemiology, Cantonal Hospital St. Gallen, Switzerland
| | - Volker Thiel
- Institute of Virology and Immunology, Bern, Switzerland; Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Jorge E Vidal
- Department of Cell and Molecular Biology, and Center for Immunology and Microbial Research, University of Mississippi Medical Center, Jackson, MS, USA
| | - Werner C Albrich
- Division of Infectious Diseases & Hospital Epidemiology, Cantonal Hospital St. Gallen, Switzerland.
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Michaelis C, Grohmann E. Horizontal Gene Transfer of Antibiotic Resistance Genes in Biofilms. Antibiotics (Basel) 2023; 12:antibiotics12020328. [PMID: 36830238 PMCID: PMC9952180 DOI: 10.3390/antibiotics12020328] [Citation(s) in RCA: 68] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/30/2023] [Accepted: 01/31/2023] [Indexed: 02/08/2023] Open
Abstract
Most bacteria attach to biotic or abiotic surfaces and are embedded in a complex matrix which is known as biofilm. Biofilm formation is especially worrisome in clinical settings as it hinders the treatment of infections with antibiotics due to the facilitated acquisition of antibiotic resistance genes (ARGs). Environmental settings are now considered as pivotal for driving biofilm formation, biofilm-mediated antibiotic resistance development and dissemination. Several studies have demonstrated that environmental biofilms can be hotspots for the dissemination of ARGs. These genes can be encoded on mobile genetic elements (MGEs) such as conjugative and mobilizable plasmids or integrative and conjugative elements (ICEs). ARGs can be rapidly transferred through horizontal gene transfer (HGT) which has been shown to occur more frequently in biofilms than in planktonic cultures. Biofilm models are promising tools to mimic natural biofilms to study the dissemination of ARGs via HGT. This review summarizes the state-of-the-art of biofilm studies and the techniques that visualize the three main HGT mechanisms in biofilms: transformation, transduction, and conjugation.
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Gazioglu O, Habtom M, Andrew PW, Yesilkaya H. The involvement of CiaR and the CiaR-regulated serine protease HtrA in thermal adaptation of Streptococcus pneumoniae. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36811449 DOI: 10.1099/mic.0.001304] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The in vivo temperature can vary according to the host tissue and the response to infection. Streptococcus pneumoniae has evolved mechanisms to survive these temperature differences, but neither the consequences of different temperatures for pneumococcal phenotype nor the genetic basis of thermal adaptation are known in detail. In our previous study [16], we found that CiaR, which is a part of two-component regulatory system CiaRH, as well as 17 genes known to be controlled by CiaRH, were identified to be differentially expressed with temperature. One of the CiaRH-regulated genes shown to be differentially regulated by temperature is for the high-temperature requirement protein (HtrA), coded by SPD_2068 (htrA). In this study, we hypothesized that the CiaRH system plays an important role in pneumococcal thermal adaptation through its control over htrA. This hypothesis was evaluated by testing strains mutated or overexpressing ciaR and/or htrA, in in vitro and in vivo assays. The results showed that in the absence of ciaR, the growth, haemolytic activity, amount of capsule and biofilm formation were considerably diminished at 40 °C only, while the cell size and virulence were affected at both 34 and 40 °C. The overexpression of htrA in the ∆ciaR background reconstituted the growth at all temperatures, and the haemolytic activity, biofilm formation and virulence of ∆ciaR partially at 40 °C. We also showed that overexpression of htrA in the wild-type promoted pneumococcal virulence at 40 °C, while the increase of capsule was observed at 34 °C, suggesting that the role of htrA changes at different temperatures. Our data suggest that CiaR and HtrA play an important role in pneumococcal thermal adaptation.
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Affiliation(s)
- Ozcan Gazioglu
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Medhanie Habtom
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Peter W Andrew
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Hasan Yesilkaya
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
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Gazioglu O, Kareem BO, Afzal M, Shafeeq S, Kuipers OP, Ulijasz AT, Andrew PW, Yesilkaya H. Glutamate Dehydrogenase (GdhA) of Streptococcus pneumoniae Is Required for High Temperature Adaptation. Infect Immun 2021; 89:e0040021. [PMID: 34491792 PMCID: PMC8594611 DOI: 10.1128/iai.00400-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 08/25/2021] [Indexed: 11/20/2022] Open
Abstract
During its progression from the nasopharynx to other sterile and nonsterile niches of its human host, Streptococcus pneumoniae must cope with changes in temperature. We hypothesized that the temperature adaptation is an important facet of pneumococcal survival in the host. Here, we evaluated the effect of temperature on pneumococcus and studied the role of glutamate dehydrogenase (GdhA) in thermal adaptation associated with virulence and survival. Microarray analysis revealed a significant transcriptional response to changes in temperature, affecting the expression of 252 genes in total at 34°C and 40°C relative to at 37°C. One of the differentially regulated genes was gdhA, which is upregulated at 40°C and downregulated at 34°C relative to 37°C. Deletion of gdhA attenuated the growth, cell size, biofilm formation, pH survival, and biosynthesis of proteins associated with virulence in a temperature-dependent manner. Moreover, deletion of gdhA stimulated formate production irrespective of temperature fluctuation. Finally, ΔgdhA grown at 40°C was less virulent than other temperatures or the wild type at the same temperature in a Galleria mellonella infection model, suggesting that GdhA is required for pneumococcal virulence at elevated temperature.
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Affiliation(s)
- Ozcan Gazioglu
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Banaz O. Kareem
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
- Department of Medical Laboratory Science, College of Medicals and Applied Sciences, University of Charmo, Chamchamal, Iraq
| | - Muhammad Afzal
- Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Sulman Shafeeq
- Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Oscar P. Kuipers
- Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - Andrew T. Ulijasz
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Peter W. Andrew
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Hasan Yesilkaya
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
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10
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Michalska M, Divan R, Noirot P, Laible PD. Antimicrobial properties of nanostructured surfaces - demonstrating the need for a standard testing methodology. NANOSCALE 2021; 13:17603-17614. [PMID: 34668503 DOI: 10.1039/d1nr02953c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bioinspired nanostructured materials that exhibit antimicrobial properties are being synthesized and tested at increasing rates for use in healthcare, manufacturing processes, and diagnostics. Although progress has been made in improving and understanding their bactericidal activity, arguably, the biggest problem currently in the field is the lack of a standard testing methodology that allows for optimal characterization and better comparison of emerging nanostructures. Here, we examine two forms of nanostructured silicon that vary in their ability to kill certain bacterial species due to different physical mechanisms and derive guidelines for the comparative testing. We perform a comprehensive evaluation of methodologies used extensively in the field (e.g., colony counting and live dead analysis) and the novel application of high-throughput flow cytometry. The data reveal how the techniques are complementary but not always directly equivalent or correlative. Therefore, comparison of results obtained using different methodologies on different materials can be grossly misleading. We report significant variations in bactericidal efficiencies depending on experimental environments (medium type, etc.) and methodologies employed. In addition, we demonstrate how cytometry is yet another powerful complementary tool that can aid the mechanistic understanding of antimicrobial activities of rough surfaces. Besides standardization for comparison, ultimately, evaluation methods need to consider anticipated applications. Then and only then can the true potential (or limitation) of a novel material be determined for its suitability for advancement in a particular field of use.
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Affiliation(s)
- Martyna Michalska
- Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | - Ralu Divan
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Philippe Noirot
- Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | - Philip D Laible
- Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.
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11
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Pieranski MK, Rychlowski M, Grinholc M. Optimization of Streptococcus agalactiae Biofilm Culture in a Continuous Flow System for Photoinactivation Studies. Pathogens 2021; 10:1212. [PMID: 34578244 PMCID: PMC8465167 DOI: 10.3390/pathogens10091212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 11/16/2022] Open
Abstract
Streptococcus agalactiae is a relevant cause of neonatal mortality. It can be transferred to infants via the vaginal tract and cause meningitis, pneumonia, arthritis, or sepsis, among other diseases. The cause of therapy ineffectiveness and infection recurrence is the growth of bacteria as biofilms. To date, several research teams have attempted to find a suitable medium for the cultivation of S. agalactiae biofilms. Among others, simulated vaginal fluid has been used; however, biofilm production in this medium has been found to be lower than that in tryptic soy broth. We have previously shown that S. agalactiae can be successfully eradicated by photoinactivation in planktonic culture, but there have been no studies on biofilms. The aim of this study was to optimize S. agalactiae biofilm culture conditions to be used in photoinactivation studies. We compared biofilm production by four strains representing the most common serotypes in four different broth media with crystal violet staining. Then, we evaluated stationary biofilm culture in microtiter plates and biofilm growth in a CDC Biofilm Reactor® (BioSurface Technologies, Bozeman, MT, USA) under continuous flow conditions. Subsequently, we applied Rose Bengal-mediated photoinactivation to both biofilm models. We have shown that photoinactivation is efficient in biofilm eradication and is not cyto/phototoxic to human keratinocytes. We found conditions allowing for stable and repetitive S. agalactiae biofilm growth in continuous flow conditions, which can be successfully utilized in photoinactivation assays and potentially in all other antibacterial studies.
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Affiliation(s)
- Michal K. Pieranski
- Laboratory of Photobiology and Molecular Diagnostics, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland;
| | - Michal Rychlowski
- Laboratory of Virus Molecular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland;
| | - Mariusz Grinholc
- Laboratory of Photobiology and Molecular Diagnostics, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland;
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Fuji N, Pichichero ME, Kaur R. Comparison of specific in-vitro virulence gene expression and innate host response in locally invasive vs colonizer strains of Streptococcus pneumoniae. Med Microbiol Immunol 2021; 210:111-120. [PMID: 33751214 DOI: 10.1007/s00430-021-00701-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 02/27/2021] [Indexed: 10/21/2022]
Abstract
Among Rochester NY children, a dramatic increase in nasopharyngeal (NP) colonization by non-vaccine pneumococcal serotypes 35B and 15A occurred during years 2010-2015, after introduction of 13-valent pneumococcal conjugate vaccine (PCV13). In our population, serotype 35B strains colonized in the nasopharynx (NP) but infrequently caused acute otitis media (AOM) whereas serotype 15A strains displayed virulence, evidenced by causing AOM. To explain the virulence difference, virulence genes expression between 35B and 15A, as well as the host's immune response during asymptomatic colonization were analyzed. We investigated differences in regulation of 19 virulence genes for differences in virulence using RT-PCR in 20 35B and 14 15A strains and measured gene expression of 9 host innate cytokines in the NP to assess the mucosal inflammatory response during asymptomatic colonization. Comparing 35B versus 15A strains, genes for competence ComA and RrgC were upregulated; capsular (Cps2D) and virulence genes (PfbA, PcpA and PhtE) were downregulated among 35B strains. PavB, LytA, LytB, NanA, CiaR, PhtD, LuxS, PspA and pneumolysin (Ply) showed no difference. IL17 and IL23 gene expression were > tenfold higher during 35B compared to 15A strain asymptomatic colonization. Only IL23 showed significant difference. In the first 5 years after introduction of PCV13, serotype 35B strains emerged as asymptomatic colonizers and 15A strains emerged to cause AOM in young children. Various genes (PfbA, PcpA, Cps2D and PhtE) among tested in this analysis were downregulated in 35B whereas ComA and RrgC were significantly upregulated. For the host's cytokine response, IL23 proinflammatory response which is essential for the differentiation of Th17 lymphocytes in the NP of children with 35B strains was significantly higher than the response to 15A during asymptomatic colonization.
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Affiliation(s)
- Naoko Fuji
- Center for Infectious Diseases and Immunology, Rochester General Hospital Research Institute, Rochester General Hospital, 1425 Portland Avenue, Rochester, NY, 14621, USA
| | - Michael E Pichichero
- Center for Infectious Diseases and Immunology, Rochester General Hospital Research Institute, Rochester General Hospital, 1425 Portland Avenue, Rochester, NY, 14621, USA
| | - Ravinder Kaur
- Center for Infectious Diseases and Immunology, Rochester General Hospital Research Institute, Rochester General Hospital, 1425 Portland Avenue, Rochester, NY, 14621, USA.
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Hemoglobin Induces Early and Robust Biofilm Development in Streptococcus pneumoniae by a Pathway That Involves comC but Not the Cognate comDE Two-Component System. Infect Immun 2021; 89:IAI.00779-20. [PMID: 33397818 DOI: 10.1128/iai.00779-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae grows in biofilms during both asymptomatic colonization and infection. Pneumococcal biofilms on abiotic surfaces exhibit delayed growth and lower biomass and lack the structures seen on epithelial cells or during nasopharyngeal carriage. We show here that adding hemoglobin to the medium activated unusually early and vigorous biofilm growth in multiple S. pneumoniae serotypes grown in batch cultures on abiotic surfaces. Human blood (but not serum, heme, or iron) also stimulated biofilms, and the pore-forming pneumolysin, ply, was required for this induction. S. pneumoniae transitioning from planktonic into sessile growth in the presence of hemoglobin displayed an extensive transcriptome remodeling within 1 and 2 h. Differentially expressed genes included those involved in the metabolism of carbohydrates, nucleotides, amino acid, and lipids. The switch into adherent states also influenced the expression of several regulatory systems, including the comCDE genes. Inactivation of comC resulted in 67% reduction in biofilm formation, while the deletion of comD or comE had limited or no effect, respectively. These observations suggest a novel route for CSP-1 signaling independent of the cognate ComDE two-component system. Biofilm induction and the associated transcriptome remodeling suggest hemoglobin serves as a signal for host colonization in pneumococcus.
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14
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Yuan X, Liu J, Li R, Zhou J, Wei J, Jiao S, Wang ZA, Du Y. Chitosan Oligosaccharides Coupling Inhibits Bacterial Biofilm-Related Antibiotic Resistance against Florfenicol. Molecules 2020; 25:molecules25246043. [PMID: 33371321 PMCID: PMC7767115 DOI: 10.3390/molecules25246043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/13/2020] [Accepted: 12/16/2020] [Indexed: 11/16/2022] Open
Abstract
The formation of bacterial biofilms has increased the resistance of bacteria to various environmental factors and is tightly associated with many persistent and chronic bacterial infections. Herein we design a strategy conjugating florfenicol, an antibiotic commonly used in the treatment of streptococcus, with the antimicrobial biomaterial, chitosan oligosaccharides. The results demonstrated that the florfenicol-COS conjugate (F-COS) efficiently eradicated the mature Streptococcus hyovaginalis biofilm, apparently inhibiting drug resistance to florfenicol. A quantity of 250 μg/mL F-COS showed effective inhibitory activity against planktonic cells and biofilm of the bacteria, and a 4-fold improvement of the F-COS compared to unmodified florfenicol was observed. Furthermore, the conjugate showed a broad-spectrum activity against both Gram-positive and Gram-negative bacteria. It suggested that F-COS might have a potential for application in the treatment of biofilm-related infections.
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Affiliation(s)
- Xianghua Yuan
- College of Life Science, Sichuan Normal University, Chengdu 610101, China; (X.Y.); (J.Z.)
| | - Jing Liu
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; (J.L.); (R.L.); (J.W.); (S.J.)
| | - Ruilian Li
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; (J.L.); (R.L.); (J.W.); (S.J.)
- College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junlin Zhou
- College of Life Science, Sichuan Normal University, Chengdu 610101, China; (X.Y.); (J.Z.)
| | - Jinhua Wei
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; (J.L.); (R.L.); (J.W.); (S.J.)
| | - Siming Jiao
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; (J.L.); (R.L.); (J.W.); (S.J.)
| | - Zhuo A. Wang
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; (J.L.); (R.L.); (J.W.); (S.J.)
- College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (Z.A.W.); (Y.D.); Tel.: +86-10-8254-5070 (Z.A.W.)
| | - Yuguang Du
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China; (J.L.); (R.L.); (J.W.); (S.J.)
- College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (Z.A.W.); (Y.D.); Tel.: +86-10-8254-5070 (Z.A.W.)
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Deciphering Streptococcal Biofilms. Microorganisms 2020; 8:microorganisms8111835. [PMID: 33233415 PMCID: PMC7700319 DOI: 10.3390/microorganisms8111835] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 12/19/2022] Open
Abstract
Streptococci are a diverse group of bacteria, which are mostly commensals but also cause a considerable proportion of life-threatening infections. They colonize many different host niches such as the oral cavity, the respiratory, gastrointestinal, and urogenital tract. While these host compartments impose different environmental conditions, many streptococci form biofilms on mucosal membranes facilitating their prolonged survival. In response to environmental conditions or stimuli, bacteria experience profound physiologic and metabolic changes during biofilm formation. While investigating bacterial cells under planktonic and biofilm conditions, various genes have been identified that are important for the initial step of biofilm formation. Expression patterns of these genes during the transition from planktonic to biofilm growth suggest a highly regulated and complex process. Biofilms as a bacterial survival strategy allow evasion of host immunity and protection against antibiotic therapy. However, the exact mechanisms by which biofilm-associated bacteria cause disease are poorly understood. Therefore, advanced molecular techniques are employed to identify gene(s) or protein(s) as targets for the development of antibiofilm therapeutic approaches. We review our current understanding of biofilm formation in different streptococci and how biofilm production may alter virulence-associated characteristics of these species. In addition, we have summarized the role of surface proteins especially pili proteins in biofilm formation. This review will provide an overview of strategies which may be exploited for developing novel approaches against biofilm-related streptococcal infections.
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Abstract
Gram-positive bacteria employ an array of secreted peptides to control population-level behaviors in response to environmental cues. We review mechanistic and functional features of secreted peptides produced by the human pathogen Streptococcus pneumoniae. We discuss sequence features, mechanisms of transport, and receptors for 3 major categories of small peptides: the double-glycine peptides, the Rap, Rgg, NprR, PlcR, and PrgX (RRNPP)-binding peptides, and the lanthionine-containing peptides. We highlight the impact of factors that contribute to carriage and pathogenesis, specifically genetic diversity, microbial competition, biofilm development, and environmental adaptation. A recent expansion in pneumococcal peptide studies reveals a complex network of interacting signaling systems where multiple peptides are integrated into the same signaling pathway, allowing multiple points of entry into the pathway and extending information content in new directions. In addition, since peptides are present in the extracellular milieu, there are opportunities for crosstalk, quorum sensing (QS), as well as intra- and interstrain and species interactions. Knowledge on the manner that population-level behaviors contribute to disease provides an avenue for the design and development of anti-infective strategies.
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Domenech M, García E. The N-Acetylglucosaminidase LytB of Streptococcus pneumoniae Is Involved in the Structure and Formation of Biofilms. Appl Environ Microbiol 2020; 86:e00280-20. [PMID: 32198170 PMCID: PMC7205503 DOI: 10.1128/aem.00280-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 03/15/2020] [Indexed: 02/07/2023] Open
Abstract
The N-acetylglucosaminidase LytB of Streptococcus pneumoniae is involved in nasopharyngeal colonization and is responsible for cell separation at the end of cell division; thus, ΔlytB mutants form long chains of cells. This paper reports the construction and properties of a defective pneumococcal mutant producing an inactive LytB protein (LytBE585A). It is shown that an enzymatically active LytB is required for in vitro biofilm formation, as lytB mutants (either ΔlytB or producing the inactive LytBE585A) are incapable of forming substantial biofilms, despite that extracellular DNA is present in the biofilm matrix. Adding small amounts (0.5 to 2.0 μg/ml) of exogenous LytB or some LytB constructs restored the biofilm-forming capacity of lytB mutants to wild-type levels. The LytBE585A mutant formed biofilm more rapidly than ΔlytB mutants in the presence of LytB. This suggests that the mutant protein acted in a structural role, likely through the formation of complexes with extracellular DNA. The chain-dispersing capacity of LytB allowed the separation of daughter cells, presumably facilitating the formation of microcolonies and, finally, of biofilms. A role for the possible involvement of LytB in the synthesis of the extracellular polysaccharide component of the biofilm matrix is also discussed.IMPORTANCE It has been previously accepted that biofilm formation in S. pneumoniae must be a multigenic trait because the mutation of a single gene has led to only to partial inhibition of biofilm production. In the present study, however, evidence that the N-acetylglucosaminidase LytB is crucial in biofilm formation is provided. Despite the presence of extracellular DNA, strains either deficient in LytB or producing a defective LytB enzyme formed only shallow biofilms.
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Affiliation(s)
- Mirian Domenech
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Ernesto García
- Departamento de Biotecnología Microbiana y de Plantas, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain
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18
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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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LuxS/AI-2 Quorum Sensing System in Edwardsiella piscicida Promotes Biofilm Formation and Pathogenicity. Infect Immun 2020; 88:IAI.00907-19. [PMID: 32071069 DOI: 10.1128/iai.00907-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 02/06/2020] [Indexed: 12/14/2022] Open
Abstract
LuxS/AI-2 is an important quorum sensing system which affects the growth, biofilm formation, virulence, and metabolism of bacteria. LuxS is encoded by the luxS gene, but how this gene is associated with a diverse array of physiological activities in Edwardsiella piscicida (E. piscicida) is not known. Here, we constructed an luxS gene mutant strain, the △luxS strain, to identify how LuxS/AI-2 affects pathogenicity. The results showed that LuxS was not found in the luxS gene mutant strain, and this gene deletion decreased E. piscicida growth compared to that of the wild-type strain. Meanwhile, the wild-type strain significantly increased penetration and motility in mucin compared to levels with the △luxS strain. The 50% lethal dose (LD50) of the E. piscicida △luxS strain for zebrafish was significantly higher than that of the wild-type strain, which suggested that the luxS gene deletion could attenuate the strain's virulence. The AI-2 activities of EIB202 were 56-fold higher than those in the △luxS strain, suggesting that the luxS gene promotes AI-2 production. Transcriptome results demonstrated that between cells infected with the △luxS strain and those infected with the wild-type strain 46 genes were significantly differentially regulated, which included 34 upregulated genes and 12 downregulated genes. Among these genes, the largest number were closely related to cell immunity and signaling systems. In addition, the biofilm formation ability of EIB202 was significantly higher than that of the △luxS strain. The supernatant of EIB202 increased the biofilm formation ability of the △luxS strain, which suggested that the luxS gene and its product LuxS enhanced biofilm formation in E. piscicida All results indicate that the LuxS/AI-2 quorum sensing system in E. piscicida promotes its pathogenicity through increasing a diverse array of physiological activities.
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20
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De Ste Croix M, Mitsi E, Morozov A, Glenn S, Andrew PW, Ferreira DM, Oggioni MR. Phase variation in pneumococcal populations during carriage in the human nasopharynx. Sci Rep 2020; 10:1803. [PMID: 32019989 PMCID: PMC7000782 DOI: 10.1038/s41598-020-58684-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 12/28/2019] [Indexed: 11/10/2022] Open
Abstract
Streptococcus pneumoniae is one of the world's leading bacterial pathogens, responsible for pneumonia, septicaemia and meningitis. Asymptomatic colonisation of the nasopharynx is considered to be a prerequisite for these severe infections, however little is understood about the biological changes that permit the pneumococcus to switch from asymptomatic coloniser to invasive pathogen. A phase variable type I restriction-modification (R-M) system (SpnIII) has been linked to a change in capsule expression and to the ability to successfully colonise the murine nasopharynx. Using our laboratory data, we have developed a Markov change model that allows prediction of the expected level of phase variation within a population, and as a result measures when populations deviate from those expected at random. Using this model, we have analysed samples from the Experimental Human Pneumococcal Carriage (EHPC) project. Here we show, through mathematical modelling, that the patterns of dominant SpnIII alleles expressed in the human nasopharynx are significantly different than those predicted by stochastic switching alone. Our inter-disciplinary work demonstrates that the expression of alternative methylation patterns should be an important consideration in studies of pneumococcal colonisation.
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Affiliation(s)
- M De Ste Croix
- Department of Genetics and Genome Biology, University of Leicester, University Rd, Leicester, LE1 7RH, United Kingdom
| | - E Mitsi
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, United Kingdom
| | - A Morozov
- Department of Mathematics, University of Leicester, University Rd, Leicester, LE1 7RH, United Kingdom
- Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninskii pr., Moscow, 119071, Russia
| | - S Glenn
- Department of Respiratory Sciences, University of Leicester, University Rd, Leicester, LE1 7RH, United Kingdom
| | - P W Andrew
- Department of Respiratory Sciences, University of Leicester, University Rd, Leicester, LE1 7RH, United Kingdom
| | - D M Ferreira
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, United Kingdom
| | - M R Oggioni
- Department of Genetics and Genome Biology, University of Leicester, University Rd, Leicester, LE1 7RH, United Kingdom.
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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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22
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Function of BriC peptide in the pneumococcal competence and virulence portfolio. PLoS Pathog 2018; 14:e1007328. [PMID: 30308062 PMCID: PMC6181422 DOI: 10.1371/journal.ppat.1007328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/10/2018] [Indexed: 02/07/2023] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is an opportunistic pathogen that causes otitis media, sinusitis, pneumonia, meningitis and sepsis. The progression to this pathogenic lifestyle is preceded by asymptomatic colonization of the nasopharynx. This colonization is associated with biofilm formation; the competence pathway influences the structure and stability of biofilms. However, the molecules that link the competence pathway to biofilm formation are unknown. Here, we describe a new competence-induced gene, called briC, and demonstrate that its product promotes biofilm development and stimulates colonization in a murine model. We show that expression of briC is induced by the master regulator of competence, ComE. Whereas briC does not substantially influence early biofilm development on abiotic surfaces, it significantly impacts later stages of biofilm development. Specifically, briC expression leads to increases in biofilm biomass and thickness at 72h. Consistent with the role of biofilms in colonization, briC promotes nasopharyngeal colonization in the murine model. The function of BriC appears to be conserved across pneumococci, as comparative genomics reveal that briC is widespread across isolates. Surprisingly, many isolates, including strains from clinically important PMEN1 and PMEN14 lineages, which are widely associated with colonization, encode a long briC promoter. This long form captures an instance of genomic plasticity and functions as a competence-independent expression enhancer that may serve as a precocious point of entry into this otherwise competence-regulated pathway. Moreover, overexpression of briC by the long promoter fully rescues the comE-deletion induced biofilm defect in vitro, and partially in vivo. These findings indicate that BriC may bypass the influence of competence in biofilm development and that such a pathway may be active in a subset of pneumococcal lineages. In conclusion, BriC is a part of the complex molecular network that connects signaling of the competence pathway to biofilm development and colonization. Pneumococcal biofilms occur in chronic otitis media, chronic rhinosinusitis, and nasopharyngeal colonization. These biofilms are an important component of pneumococcal epidemiology, particularly in influencing transmission, maintenance of asymptomatic colonization, and development of disease. The transcriptional program initiated via signaling of the competence pathway is critical for productive biofilm formation and is a strong contributor of pneumococcal infection and adaptation. In this study, we have identified BriC, a previously uncharacterized peptide that serves as a bridge between the competence pathway and biofilm development. We show that briC is induced by ComE, the master regulator of competence, and promotes biofilm development. Moreover, our studies in the murine model demonstrate that BriC is a novel colonization enhancer. Our studies of briC regulation capture an instance of genomic plasticity, where natural variation in the briC promoter sequence reveals the existence of an additional competence-independent regulatory unit. This natural variation may be able to modify the extent to which competence contributes to biofilm development and to nasopharyngeal colonization across different pneumococcal lineages. In summary, this study introduces a colonization factor and reveals a molecular link between competence and biofilm development.
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Weyder M, Prudhomme M, Bergé M, Polard P, Fichant G. Dynamic Modeling of Streptococcus pneumoniae Competence Provides Regulatory Mechanistic Insights Into Its Tight Temporal Regulation. Front Microbiol 2018; 9:1637. [PMID: 30087661 PMCID: PMC6066662 DOI: 10.3389/fmicb.2018.01637] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 06/30/2018] [Indexed: 12/31/2022] Open
Abstract
In the human pathogen Streptococcus pneumoniae, the gene regulatory circuit leading to the transient state of competence for natural transformation is based on production of an auto-inducer that activates a positive feedback loop. About 100 genes are activated in two successive waves linked by a central alternative sigma factor ComX. This mechanism appears to be fundamental to the biological fitness of S. pneumoniae. We have developed a knowledge-based model of the competence cycle that describes average cell behavior. It reveals that the expression rates of the two competence operons, comAB and comCDE, involved in the positive feedback loop must be coordinated to elicit spontaneous competence. Simulations revealed the requirement for an unknown late com gene product that shuts of competence by impairing ComX activity. Further simulations led to the predictions that the membrane protein ComD bound to CSP reacts directly to pH change of the medium and that blindness to CSP during the post-competence phase is controlled by late DprA protein. Both predictions were confirmed experimentally.
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Affiliation(s)
| | - Marc Prudhomme
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative, Université de Toulouse, CNRS, Université Toulouse III Paul Sabatier, Toulouse, France
| | | | | | - Gwennaele Fichant
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative, Université de Toulouse, CNRS, Université Toulouse III Paul Sabatier, Toulouse, France
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Yadav MK, Vidal JE, Go YY, Kim SH, Chae SW, Song JJ. The LuxS/AI-2 Quorum-Sensing System of Streptococcus pneumoniae Is Required to Cause Disease, and to Regulate Virulence- and Metabolism-Related Genes in a Rat Model of Middle Ear Infection. Front Cell Infect Microbiol 2018; 8:138. [PMID: 29780750 PMCID: PMC5945837 DOI: 10.3389/fcimb.2018.00138] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/18/2018] [Indexed: 01/02/2023] Open
Abstract
Objective:Streptococcus pneumoniae colonizes the nasopharynx of children, and from nasopharynx it could migrate to the middle ear and causes acute otitis media (AOM). During colonization and AOM, the pneumococcus forms biofilms. In vitro biofilm formation requires a functional LuxS/AI-2 quorum-sensing system. We investigated the role of LuxS/AI-2 signaling in pneumococcal middle ear infection, and identified the genes that are regulated by LuxS/AI-2 during pneumococcal biofilm formation. Methods:Streptococcus pneumoniae D39 wild-type and an isogenic D39ΔluxS strain were utilized to evaluate in vitro biofilm formation, and in vivo colonization and epithelial damage using a microtiter plate assay and a rat model of pneumococcal middle ear infection, respectively. Biofilm structures and colonization and epithelial damage were evaluated at the ultrastructural level by scanning electron microscopy and confocal microscopy. Microarrays were used to investigate the global genes that were regulated by LuxS/AI-2 during biofilm formation. Results: The biofilm biomass and density of D39ΔluxS were significantly (p < 0.05) lower than those of D39 wild-type. SEM and confocal microscopy revealed that D39ΔluxS formed thin biofilms in vitro compared with D39 wild-type. The in vivo model of middle ear infection showed that D39ΔluxS resulted in ~60% less (p < 0.05) bacterial colonization than the wild-type. SEM analysis of the rat middle ears revealed dense biofilm-like cell debris deposited on the cilia in wild-type D39-infected rats. However, little cell debris was deposited in the middle ears of the D39ΔluxS-inoculated rats, and the cilia were visible. cDNA-microarray analysis revealed 117 differentially expressed genes in D39ΔluxS compared with D39 wild-type. Among the 66 genes encoding putative proteins and previously characterized proteins, 60 were significantly downregulated, whereas 6 were upregulated. Functional annotation revealed that genes involved in DNA replication and repair, ATP synthesis, capsule biosynthesis, cell division, the cell cycle, signal transduction, transcription regulation, competence, virulence, and carbohydrate metabolism were downregulated in the absence of LuxS/AI-2. Conclusion: The S. pneumoniae LuxS/AI-2 quorum-sensing system is necessary for biofilm formation and the colonization of the ear epithelium, and caused middle ear infection in the rat model. LuxS/AI-2 regulates the expression of the genes involved in virulence and bacterial fitness during pneumococcal biofilm formation.
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Affiliation(s)
- Mukesh K Yadav
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea.,Institute for Medical Device Clinical Trials, Korea University College of Medicine, Seoul, South Korea
| | - Jorge E Vidal
- Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Yoon Y Go
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Shin H Kim
- 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
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
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Sjollema J, Zaat SAJ, Fontaine V, Ramstedt M, Luginbuehl R, Thevissen K, Li J, van der Mei HC, Busscher HJ. In vitro methods for the evaluation of antimicrobial surface designs. Acta Biomater 2018; 70:12-24. [PMID: 29432983 DOI: 10.1016/j.actbio.2018.02.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/12/2018] [Accepted: 02/01/2018] [Indexed: 11/16/2022]
Abstract
Bacterial adhesion and subsequent biofilm formation on biomedical implants and devices are a major cause of their failure. As systemic antibiotic treatment is often ineffective, there is an urgent need for antimicrobial biomaterials and coatings. The term "antimicrobial" can encompass different mechanisms of action (here termed "antimicrobial surface designs"), such as antimicrobial-releasing, contact-killing or non-adhesivity. Biomaterials equipped with antimicrobial surface designs based on different mechanisms of action require different in vitro evaluation methods. Available industrial standard evaluation tests do not address the specific mechanisms of different antimicrobial surface designs and have therefore been modified over the past years, adding to the myriad of methods available in the literature to evaluate antimicrobial surface designs. The aim of this review is to categorize fourteen presently available methods including industrial standard tests for the in vitro evaluation of antimicrobial surface designs according to their suitability with respect to their antimicrobial mechanism of action. There is no single method or industrial test that allows to distinguish antimicrobial designs according to all three mechanisms identified here. However, critical consideration of each method clearly relates the different methods to a specific mechanism of antimicrobial action. It is anticipated that use of the provided table with the fourteen methods will avoid the use of wrong methods for evaluating new antimicrobial designs and therewith facilitate translation of novel antimicrobial biomaterials and coatings to clinical use. The need for more and better updated industrial standard tests is emphasized. STATEMENT OF SIGNIFICANCE European COST-action TD1305, IPROMEDAI aims to provide better understanding of mechanisms of antimicrobial surface designs of biomaterial implants and devices. Current industrial evaluation standard tests do not sufficiently account for different, advanced antimicrobial surface designs, yet are urgently needed to obtain convincing in vitro data for approval of animal experiments and clinical trials. This review aims to provide an innovative and clear guide to choose appropriate evaluation methods for three distinctly different mechanisms of antimicrobial design: (1) antimicrobial-releasing, (2) contact-killing and (3) non-adhesivity. Use of antimicrobial evaluation methods and definition of industrial standard tests, tailored toward the antimicrobial mechanism of the design, as identified here, fulfill a missing link in the translation of novel antimicrobial surface designs to clinical use.
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Affiliation(s)
- Jelmer Sjollema
- University of Groningen, University Medical Center Groningen, Department of BioMedical Engineering, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
| | - Sebastian A J Zaat
- Department of Medical Microbiology, CINIMA (Center for Infection and Immunity Amsterdam), Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Veronique Fontaine
- Unit of Pharmaceutical Microbiology and Hygiene, Faculty of Pharmacy, Université Libre de Bruxelles (ULB), Campus Plaine, Boulevard du Triomphe, 1050 Brussels, Belgium
| | | | - Reto Luginbuehl
- RMS Foundation, Bischmattstrasse 12, 2544 Bettlach, Switzerland
| | - Karin Thevissen
- Centre for Microbial and Plant Genetics, CMPG, University of Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium
| | - Jiuyi Li
- School of Civil Engineering, Beijing Jiaotong University, 3 Shangyuancun, Xizhimenwai, Beijing 100044, China
| | - Henny C van der Mei
- University of Groningen, University Medical Center Groningen, Department of BioMedical Engineering, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Henk J Busscher
- University of Groningen, University Medical Center Groningen, Department of BioMedical Engineering, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
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Nesse LL, Simm R. Biofilm: A Hotspot for Emerging Bacterial Genotypes. ADVANCES IN APPLIED MICROBIOLOGY 2018; 103:223-246. [PMID: 29914658 DOI: 10.1016/bs.aambs.2018.01.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Bacteria have the ability to adapt to changing environments through rapid evolution mediated by modification of existing genetic information, as well as by horizontal gene transfer (HGT). This makes bacteria a highly successful life form when it comes to survival. Unfortunately, this genetic plasticity may result in emergence and dissemination of antimicrobial resistance and virulence genes, and even the creation of multiresistant "superbugs" which may pose serious threats to public health. As bacteria commonly reside in biofilms, there has been an increased interest in studying these phenomena within biofilms in recent years. This review summarizes the present knowledge within this important area of research. Studies on bacterial evolution in biofilms have shown that mature biofilms develop into diverse communities over time. There is growing evidence that the biofilm lifestyle may be more mutagenic than planktonic growth. Furthermore, all three main mechanisms for HGT have been observed in biofilms. This has been shown to occur both within and between bacterial species, and higher transfer rates in biofilms than in planktonic cultures were detected. Of special concern are the observations that mutants with increased antibiotic resistance occur at higher frequency in biofilms than in planktonic cultures even in the absence of antibiotic exposure. Likewise, efficient dissemination of antimicrobial resistance genes, as well as virulence genes, has been observed within the biofilm environment. This new knowledge emphasizes the importance of biofilm awareness and control.
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27
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Jurcisek JA, Brockman KL, Novotny LA, Goodman SD, Bakaletz LO. Nontypeable Haemophilus influenzae releases DNA and DNABII proteins via a T4SS-like complex and ComE of the type IV pilus machinery. Proc Natl Acad Sci U S A 2017; 114:E6632-E6641. [PMID: 28696280 PMCID: PMC5559034 DOI: 10.1073/pnas.1705508114] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Biofilms formed by nontypeable Haemophilus influenzae (NTHI) are central to the chronicity, recurrence, and resistance to treatment of multiple human respiratory tract diseases including otitis media, chronic rhinosinusitis, and exacerbations of both cystic fibrosis and chronic obstructive pulmonary disease. Extracellular DNA (eDNA) and associated DNABII proteins are essential to the overall architecture and structural integrity of biofilms formed by NTHI and all other bacterial pathogens tested to date. Although cell lysis and outer-membrane vesicle extrusion are possible means by which these canonically intracellular components might be released into the extracellular environment for incorporation into the biofilm matrix, we hypothesized that NTHI additionally used a mechanism of active DNA release. Herein, we describe a mechanism whereby DNA and associated DNABII proteins transit from the bacterial cytoplasm to the periplasm via an inner-membrane pore complex (TraC and TraG) with homology to type IV secretion-like systems. These components exit the bacterial cell through the ComE pore through which the NTHI type IV pilus is expressed. The described mechanism is independent of explosive cell lysis or cell death, and the release of DNA is confined to a discrete subpolar location, which suggests a novel form of DNA release from viable NTHI. Identification of the mechanisms and determination of the kinetics by which critical biofilm matrix-stabilizing components are released will aid in the design of novel biofilm-targeted therapeutic and preventative strategies for diseases caused by NTHI and many other human pathogens known to integrate eDNA and DNABII proteins into their biofilm matrix.
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Affiliation(s)
- Joseph A Jurcisek
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205
| | - Kenneth L Brockman
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210
| | - Laura A Novotny
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205
| | - Steven D Goodman
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210
| | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205;
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210
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28
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Cuevas RA, Eutsey R, Kadam A, West-Roberts JA, Woolford CA, Mitchell AP, Mason KM, Hiller NL. A novel streptococcal cell-cell communication peptide promotes pneumococcal virulence and biofilm formation. Mol Microbiol 2017; 105:554-571. [PMID: 28557053 DOI: 10.1111/mmi.13721] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2017] [Indexed: 12/29/2022]
Abstract
Streptococcus pneumoniae (pneumococcus) is a major human pathogen. It is a common colonizer of the human respiratory track, where it utilizes cell-cell communication systems to coordinate population-level behaviors. We reasoned that secreted peptides that are highly expressed during infection are pivotal for virulence. Thus, we used in silico pattern searches to define a pneumococcal secretome and analyzed the transcriptome of the clinically important PMEN1 lineage to identify which peptide-encoding genes are highly expressed in vivo. In this study, we characterized virulence peptide 1 (vp1), a highly expressed Gly-Gly peptide-encoding gene in chinchilla middle ear effusions. The vp1 gene is widely distributed across pneumococcus as well as encoded in related species. Studies in the chinchilla model of middle ear infection demonstrated that VP1 is a virulence determinant. The vp1 gene is positively regulated by a transcription factor from the Rgg family and its cognate SHP (short hydrophobic peptide). In vitro data indicated that VP1 promotes increased thickness and biomass for biofilms grown on chinchilla middle ear epithelial cells. Furthermore, the wild-type biofilm is restored with the exogenous addition of synthetic VP1. We conclude that VP1 is a novel streptococcal regulatory peptide that controls biofilm development and pneumococcal pathogenesis.
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Affiliation(s)
- Rolando A Cuevas
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Rory Eutsey
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Anagha Kadam
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Jacob A West-Roberts
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Carol A Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Aaron P Mitchell
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Kevin M Mason
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - N Luisa Hiller
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.,Center of Excellence in Biofilm Research, Allegheny Health Network, Pittsburgh, PA 15211, USA
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Brown LR, Caulkins RC, Schartel TE, Rosch JW, Honsa ES, Schultz-Cherry S, Meliopoulos VA, Cherry S, Thornton JA. Increased Zinc Availability Enhances Initial Aggregation and Biofilm Formation of Streptococcus pneumoniae. Front Cell Infect Microbiol 2017. [PMID: 28638805 PMCID: PMC5461340 DOI: 10.3389/fcimb.2017.00233] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bacteria growing within biofilms are protected from antibiotics and the immune system. Within these structures, horizontal transfer of genes encoding virulence factors, and promoting antibiotic resistance occurs, making biofilms an extremely important aspect of pneumococcal colonization and persistence. Identifying environmental cues that contribute to the formation of biofilms is critical to understanding pneumococcal colonization and infection. Iron has been shown to be essential for the formation of pneumococcal biofilms; however, the role of other physiologically important metals such as copper, zinc, and manganese has been largely neglected. In this study, we investigated the effect of metals on pneumococcal aggregation and early biofilm formation. Our results show that biofilms increase as zinc concentrations increase. The effect was found to be zinc-specific, as altering copper and manganese concentrations did not affect biofilm formation. Scanning electron microscopy analysis revealed structural differences between biofilms grown in varying concentrations of zinc. Analysis of biofilm formation in a mutant strain lacking the peroxide-generating enzyme pyruvate oxidase, SpxB, revealed that zinc does not protect against pneumococcal H2O2. Further, analysis of a mutant strain lacking the major autolysin, LytA, indicated the role of zinc as a negative regulator of LytA-dependent autolysis, which could affect biofilm formation. Additionally, analysis of cell-cell aggregation via plating and microscopy revealed that high concentrations of zinc contribute to intercellular interaction of pneumococci. The findings from this study demonstrate that metal availability contributes to the ability of pneumococci to form aggregates and subsequently, biofilms.
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Affiliation(s)
- Lindsey R Brown
- Department of Biological Sciences, Mississippi State UniversityStarkville, MS, United States
| | - Rachel C Caulkins
- Department of Biological Sciences, Mississippi State UniversityStarkville, MS, United States
| | - Tyler E Schartel
- Department of Biological Sciences, Mississippi State UniversityStarkville, MS, United States
| | - Jason W Rosch
- Department of Infectious Diseases, St. Jude Children's Research HospitalMemphis, TN, United States
| | - Erin S Honsa
- Department of Infectious Diseases, St. Jude Children's Research HospitalMemphis, TN, United States
| | - Stacey Schultz-Cherry
- Department of Infectious Diseases, St. Jude Children's Research HospitalMemphis, TN, United States
| | - Victoria A Meliopoulos
- Department of Infectious Diseases, St. Jude Children's Research HospitalMemphis, TN, United States
| | - Sean Cherry
- Department of Infectious Diseases, St. Jude Children's Research HospitalMemphis, TN, United States
| | - Justin A Thornton
- Department of Biological Sciences, Mississippi State UniversityStarkville, MS, United States
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30
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Barenkamp SJ, Chonmaitree T, Hakansson AP, Heikkinen T, King S, Nokso-Koivisto J, Novotny LA, Patel JA, Pettigrew M, Swords WE. Panel 4: Report of the Microbiology Panel. Otolaryngol Head Neck Surg 2017; 156:S51-S62. [PMID: 28372529 PMCID: PMC5490388 DOI: 10.1177/0194599816639028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 02/24/2016] [Indexed: 12/12/2022]
Abstract
Objective To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.
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Affiliation(s)
- Stephen J. Barenkamp
- Department of Pediatrics, St Louis University School of Medicine, St Louis, Missouri, USA
| | - Tasnee Chonmaitree
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | | | - Terho Heikkinen
- Department of Pediatrics, University of Turku and Turku University Hospital, Turku, Finland
| | - Samantha King
- The Research Institute at Nationwide Children’s Hospital and Ohio State University, Columbus, Ohio, USA
| | - Johanna Nokso-Koivisto
- Department of Otorhinolaryngology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Laura A. Novotny
- The Research Institute at Nationwide Children’s Hospital and Ohio State University, Columbus, Ohio, USA
| | - Janak A. Patel
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Melinda Pettigrew
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, USA
| | - W. Edward Swords
- Department of Microbiology and Immunology, Wake Forest University, Winston-Salem, North Carolina, USA
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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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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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Sinefungin, a natural nucleoside analogue of S-adenosylmethionine, inhibits Streptococcus pneumoniae biofilm growth. BIOMED RESEARCH INTERNATIONAL 2014; 2014:156987. [PMID: 25050323 PMCID: PMC4094849 DOI: 10.1155/2014/156987] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 06/05/2014] [Accepted: 06/08/2014] [Indexed: 01/21/2023]
Abstract
Pneumococcal colonization and disease is often associated with biofilm formation, in which the bacteria exhibit elevated resistance both to antibiotics and to host defense systems, often resulting in infections that are persistent and difficult to treat. We evaluated the effect of sinefungin, a nucleoside analogue of S-adenosylmethionine, on pneumococcal in vitro biofilm formation and in vivo colonization. Sinefungin is bacteriostatic to pneumococci and significantly decreased biofilm growth and inhibited proliferation and structure of actively growing biofilms but did not alter growth or the matrix structure of established biofilms. Sinefungin significantly reduced pneumococcal colonization in rat middle ear. The quorum sensing molecule (autoinducer-2) production was significantly reduced by 92% in sinefungin treated samples. The luxS, pfs, and speE genes were downregulated in biofilms grown in the presence of sinefungin. This study shows that sinefungin inhibits pneumococcal biofilm growth in vitro and colonization in vivo, decreases AI-2 production, and downregulates luxS, pfs, and speE gene expressions. Therefore, the S-adenosylmethionine (SAM) inhibitors could be used as lead compounds for the development of novel antibiofilm agents against pneumococci.
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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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Functional screening of a metagenomic library reveals operons responsible for enhanced intestinal colonization by gut commensal microbes. Appl Environ Microbiol 2013; 79:3829-38. [PMID: 23584783 DOI: 10.1128/aem.00581-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Evidence suggests that gut microbes colonize the mammalian intestine through propagation as an adhesive microbial community. A bacterial artificial chromosome (BAC) library of murine bowel microbiota DNA in the surrogate host Escherichia coli DH10B was screened for enhanced adherence capability. Two out of 5,472 DH10B clones, 10G6 and 25G1, exhibited enhanced capabilities to adhere to inanimate surfaces in functional screens. DNA segments inserted into the 10G6 and 25G1 clones were 52 and 41 kb and included 47 and 41 protein-coding open reading frames (ORFs), respectively. DNA sequence alignments, tetranucleotide frequency, and codon usage analysis strongly suggest that these two DNA fragments are derived from species belonging to the genus Bacteroides. Consistent with this finding, a large portion of the predicted gene products were highly homologous to those of Bacteroides spp. Transposon mutagenesis and subsequent experiments that involved heterologous expression identified two operons associated with enhanced adherence. E. coli strains transformed with the 10a or 25b operon adhered to the surface of intestinal epithelium and colonized the mouse intestine more vigorously than did the control strain. This study has revealed the genetic determinants of unknown commensals (probably resembling Bacteroides species) that enhance the ability of the bacteria to colonize the murine bowel.
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Abstract
PURPOSE OF REVIEW Streptococcus pneumoniae (the pneumococcus) remains an important cause of invasive disease including bacteraemia. This review highlights recent findings related to pneumococcal bacteraemia, virulence factors, and multiple colonization, including strain competition, biofilm formation, and competence. RECENT FINDINGS Countries with no vaccination programmes see vaccine serotypes still prevalent in disease, whereas the emergence of nonvaccine serotypes in nasopharyngeal carriage and invasive disease is seen in countries with conjugate vaccination in place. Co-colonizing strains are being uncovered with more sensitive methods, and may act synergistically or compete with each other for survival. Several factors such as iron uptake, quorum signalling and the luxS gene, involved in colonization and virulence, are discussed. The role of quorum sensing signalling molecules and formation of biofilms are being explored. SUMMARY Epidemiological data suggest that the latest serotype-based conjugate vaccines should provide heightened protection, although serotype replacement is now being seen. Much remains to be elucidated about its biology during multiple colonization, when evolution and adaptation to its host take place. The modes of colonization (biofilm, intracellular or surface adherence to the mucosal epithelium), and whether organisms that cause invasive disease have attenuated ability to colonize the nasopharynx remain to be elucidated.
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Quorum-sensing systems LuxS/autoinducer 2 and Com regulate Streptococcus pneumoniae biofilms in a bioreactor with living cultures of human respiratory cells. Infect Immun 2013; 81:1341-53. [PMID: 23403556 DOI: 10.1128/iai.01096-12] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Streptococcus pneumoniae forms organized biofilms in the human upper respiratory tract that may play an essential role in both persistence and acute respiratory infection. However, the production and regulation of biofilms on human cells is not yet fully understood. In this work, we developed a bioreactor with living cultures of human respiratory epithelial cells (HREC) and a continuous flow of nutrients, mimicking the microenvironment of the human respiratory epithelium, to study the production and regulation of S. pneumoniae biofilms (SPB). SPB were also produced under static conditions on immobilized HREC. Our experiments demonstrated that the biomass of SPB increased significantly when grown on HREC compared to the amount on abiotic surfaces. Additionally, pneumococcal strains produced more early biofilms on lung cells than on pharyngeal cells. Utilizing the bioreactor or immobilized human cells, the production of early SPB was found to be regulated by two quorum-sensing systems, Com and LuxS/AI-2, since a mutation in either comC or luxS rendered the pneumococcus unable to produce early biofilms on HREC. Interestingly, while LuxS/autoinducer 2 (AI-2) regulated biofilms on both HREC and abiotic surfaces, Com control was specific for those structures produced on HREC. The biofilm phenotypes of strain D39-derivative ΔcomC and ΔluxS QS mutants were reversed by genetic complementation. Of note, SPB formed on immobilized HREC and incubated under static conditions were completely lysed 24 h postinoculation. Biofilm lysis was also regulated by the Com and LuxS/AI-2 quorum-sensing systems.
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Site of isolation determines biofilm formation and virulence phenotypes of Streptococcus pneumoniae serotype 3 clinical isolates. Infect Immun 2012. [PMID: 23208608 DOI: 10.1128/iai.01033-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is a diverse species causing invasive as well as localized infections that result in massive global morbidity and mortality. Strains vary markedly in pathogenic potential, but the molecular basis is obscured by the diversity and plasticity of the pneumococcal genome. In the present study, S. pneumoniae serotype 3 blood (n = 12) or ear (n = 13) isolates were multilocus sequence typed (MLST) and assessed for biofilm formation and virulence phenotype. Blood and ear isolates exhibited similar MLST distributions but differed markedly in phenotype. Blood isolates formed robust biofilms only at pH 7.4, which were enhanced in Fe(III)-supplemented medium. Conversely, ear isolates formed biofilms only at pH 6.8, and Fe(III) was inhibitory. Biofilm formation paralleled luxS expression and genetic competence. In a mouse intranasal challenge model, blood isolates did not stably colonize the nasopharynx but spread to the blood; none spread to the ear. Ear isolates colonized the nasopharynx at higher levels and also spread to the ear compartment in a significant proportion of animals; none caused bacteremia. Thus, pneumococci of the same serotype and MLST exhibit distinct phenotypes in accordance with clinical site of isolation, indicative of stable niche adaptation within a clonal lineage.
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High levels of genetic recombination during nasopharyngeal carriage and biofilm formation in Streptococcus pneumoniae. mBio 2012; 3:mBio.00200-12. [PMID: 23015736 PMCID: PMC3448161 DOI: 10.1128/mbio.00200-12] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Transformation of genetic material between bacteria was first observed in the 1920s using Streptococcus pneumoniae as a model organism. Since then, the mechanism of competence induction and transformation has been well characterized, mainly using planktonic bacteria or septic infection models. However, epidemiological evidence suggests that genetic exchange occurs primarily during pneumococcal nasopharyngeal carriage, which we have recently shown is associated with biofilm growth, and is associated with cocolonization with multiple strains. However, no studies to date have comprehensively investigated genetic exchange during cocolonization in vitro and in vivo or the role of the nasopharyngeal environment in these processes. In this study, we show that genetic exchange during dual-strain carriage in vivo is extremely efficient (10−2) and approximately 10,000,000-fold higher than that measured during septic infection (10−9). This high transformation efficiency was associated with environmental conditions exclusive to the nasopharynx, including the lower temperature of the nasopharynx (32 to 34°C), limited nutrient availability, and interactions with epithelial cells, which were modeled in a novel biofilm model in vitro that showed similarly high transformation efficiencies. The nasopharyngeal environmental factors, combined, were critical for biofilm formation and induced constitutive upregulation of competence genes and downregulation of capsule that promoted transformation. In addition, we show that dual-strain carriage in vivo and biofilms formed in vitro can be transformed during colonization to increase their pneumococcal fitness and also, importantly, that bacteria with lower colonization ability can be protected by strains with higher colonization efficiency, a process unrelated to genetic exchange. Although genetic exchange between pneumococcal strains is known to occur primarily during colonization of the nasopharynx and colonization is associated with biofilm growth, this is the first study to comprehensively investigate transformation in this environment and to analyze the role of environmental and bacterial factors in this process. We show that transformation efficiency during cocolonization by multiple strains is very high (around 10−2). Furthermore, we provide novel evidence that specific aspects of the nasopharyngeal environment, including lower temperature, limited nutrient availability, and epithelial cell interaction, are critical for optimal biofilm formation and transformation efficiency and result in bacterial protein expression changes that promote transformation and fitness of colonization-deficient strains. The results suggest that cocolonization in biofilm communities may have important clinical consequences by facilitating the spread of antibiotic resistance and enabling serotype switching and vaccine escape as well as protecting and retaining poorly colonizing strains in the pneumococcal strain pool.
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Yadav MK, Chae SW, Song JJ. Effect of 5-azacytidine on in vitro biofilm formation of Streptococcus pneumoniae. Microb Pathog 2012; 53:219-26. [PMID: 22963864 DOI: 10.1016/j.micpath.2012.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/04/2012] [Accepted: 08/16/2012] [Indexed: 11/18/2022]
Abstract
Streptococcus pneumoniae is a gram-positive bacterium that causes otitis media, pneumonia, meningitis and sepsis in young children and the elderly. Previous studies reported that pneumococci in different diseases do not behave as planktonic cells, but predominantly show characteristics of a biofilm. In this study we examine the effect of 5-azacytidine on S. pneumoniae, particularly on biofilm formation and investigate the gene expression involved in synthesis of autoinducer-2, competence and DNA repair. The effect of 5-aza on in vitro biofilm formation was studied by the crystal violet microtiter plate method. The S. pneumoniae biofilms were grown with different concentration of 5-azacytidine (15-500 μm), at variable time intervals and the inhibition percentages were calculated. The effects of 5-aza on the morphology of biofilms were analyzed by scanning electron microscope. The relative quantification of 11 genes of biofilms grown with 5-aza involved in autoinducer-2 synthesis, competence and DNA repair was carried out by real-time RT-PCR with respect to biofilms grown without 5-aza. The crystal violet microtiter assay detected a significant inhibitory effect of 5-aza on in vitro biofilm formation, at concentration that did not inhibited planktonic cell growth. The SEM analysis demonstrated thin and disrupted biofilms, without micro-colonies in the samples treated with 5-aza, while these structures were present in the biofilms grown without 5-aza. The relative quantification of gene expression of 5-aza biofilms showed a significant down regulation of genes involved in the methionine and homocysteine recycling pathway which produces quorum sensing molecule autoinducer-2 as by-products. A significant decrease in the expressions of luxS, metK, pfs and cmK was detected. In conclusion, 5-aza inhibits in vitro biofilm formation and decreases the expression of luxS, pfs and metK, which are involved in the synthesis of autoinducer-2 as by-products of the methionine recycling pathway. The inhibitory effect of 5-aza may be either due to down regulation of pfs, luxS and metK or due to accumulation of the toxic substrate of pfs, luxS and metK genes.
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Affiliation(s)
- Mukesh Kumar Yadav
- Department of Otorhinolaryngology-Head and Neck Surgery, Dongguk University Ilsan Hospital, 814 Siksa-Dong, Goyang, Gyeonggi 410-773, South Korea
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Pneumococcal interactions with epithelial cells are crucial for optimal biofilm formation and colonization in vitro and in vivo. Infect Immun 2012; 80:2744-60. [PMID: 22645283 DOI: 10.1128/iai.00488-12] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human nasopharynx is the main reservoir for Streptococcus pneumoniae (the pneumococcus) and the source for both horizontal spread and transition to infection. Some clinical evidence indicates that nasopharyngeal carriage is harder to eradicate with antibiotics than is pneumococcal invasive disease, which may suggest that colonizing pneumococci exist in biofilm communities that are more resistant to antibiotics. While pneumococcal biofilms have been observed during symptomatic infection, their role in colonization and the role of host factors in this process have been less studied. Here, we show for the first time that pneumococci form highly structured biofilm communities during colonization of the murine nasopharynx that display increased antibiotic resistance. Furthermore, pneumococcal biofilms grown on respiratory epithelial cells exhibited phenotypes similar to those observed during colonization in vivo, whereas abiotic surfaces produced less ordered and more antibiotic-sensitive biofilms. The importance of bacterial-epithelial cell interactions during biofilm formation was shown using both clinical strains with variable colonization efficacies and pneumococcal mutants with impaired colonization characteristics in vivo. In both cases, the ability of strains to form biofilms on epithelial cells directly correlated with their ability to colonize the nasopharynx in vivo, with colonization-deficient strains forming less structured and more antibiotic-sensitive biofilms on epithelial cells, an association that was lost when grown on abiotic surfaces. Thus, these studies emphasize the importance of host-bacterial interactions in pneumococcal biofilm formation and provide the first experimental data to explain the high resistance of pneumococcal colonization to eradication by antibiotics.
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Ojano-Dirain C, Antonelli PJ. Tympanostomy Tube In Vitro Biofilm Potential of Common Otopathogens. Otolaryngol Head Neck Surg 2012; 146:816-22. [DOI: 10.1177/0194599811435781] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective. Post-tympanostomy tube otorrhea has been linked to microbial biofilms. The purpose of this study was to compare the tympanostomy tube-biofilm–forming propensity of common otopathogens Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae. Study Design. Controlled, in vitro. Setting. Academic research laboratory. Subjects and Methods. Fluoroplastic coupons (1656 total, 46 per treatment per incubation period) were exposed to plasma and cultured with 3 strains each of the bacterial species for 2, 4, or 7 days. Half of the coupons were treated with antibiotics to kill planktonic bacteria. Total and biofilm colony counts and electron microscopy were performed. Results. S aureus formed biofilm after 2 days, not different from 4- or 7-day biofilms ( P > .05), and was most tolerant to antibiotic treatment. P aeruginosa also formed biofilms at 2 days, reached a plateau at 4 days ( P > .05), and decreased at 7 days ( P < .01). H influenzae formed biofilm only after 4 days ( P ≤ .04). S pneumoniae did not form biofilm without catalase supplementation. With catalase, 1 S pneumoniae strain showed a delay in biofilm formation similar to H influenzae ( P < .0001), while the other 2 strains formed biofilms after 2 days. Conclusions. Tympanostomy tube biofilm formation occurs with common middle ear pathogens but most readily with S aureus and P aeruginosa. Further investigation is needed to determine if these findings may, in part, explain the occasionally refractory nature of post-tympanostomy tube otorrhea associated with S aureus and P aeruginosa.
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Sanchez CJ, Kumar N, Lizcano A, Shivshankar P, Dunning Hotopp JC, Jorgensen JH, Tettelin H, Orihuela CJ. Streptococcus pneumoniae in biofilms are unable to cause invasive disease due to altered virulence determinant production. PLoS One 2011; 6:e28738. [PMID: 22174882 PMCID: PMC3234282 DOI: 10.1371/journal.pone.0028738] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 11/14/2011] [Indexed: 11/19/2022] Open
Abstract
It is unclear whether Streptococcus pneumoniae in biofilms are virulent and contribute to development of invasive pneumococcal disease (IPD). Using electron microscopy we confirmed the development of mature pneumococcal biofilms in a continuous-flow-through line model and determined that biofilm formation occurred in discrete stages with mature biofilms composed primarily of dead pneumococci. Challenge of mice with equal colony forming units of biofilm and planktonic pneumococci determined that biofilm bacteria were highly attenuated for invasive disease but not nasopharyngeal colonization. Biofilm pneumococci of numerous serotypes were hyper-adhesive and bound to A549 type II pneumocytes and Detroit 562 pharyngeal epithelial cells at levels 2 to 11-fold greater than planktonic counterparts. Using genomic microarrays we examined the pneumococcal transcriptome and determined that during biofilm formation S. pneumoniae down-regulated genes involved in protein synthesis, energy production, metabolism, capsular polysaccharide (CPS) production, and virulence. We confirmed these changes by measuring CPS by ELISA and immunoblotting for the toxin pneumolysin and the bacterial adhesins phosphorylcholine (ChoP), choline-binding protein A (CbpA), and Pneumococcal serine-rich repeat protein (PsrP). We conclude that biofilm pneumococci were avirulent due to reduced CPS and pneumolysin production along with increased ChoP, which is known to bind C-reactive protein and is opsonizing. Likewise, biofilm pneumococci were hyper-adhesive due to selection for the transparent phase variant, reduced CPS, and enhanced production of PsrP, CbpA, and ChoP. These studies suggest that biofilms do not directly contribute to development of IPD and may instead confer a quiescent mode of growth during colonization.
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Affiliation(s)
- Carlos J. Sanchez
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Nikhil Kumar
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Anel Lizcano
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Pooja Shivshankar
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Julie C. Dunning Hotopp
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James H. Jorgensen
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- Department of Pathology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Hervé Tettelin
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Carlos J. Orihuela
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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Abstract
Biofilm‐grown bacteria are refractory to antimicrobial agents and show an increased capacity to evade the host immune system. In recent years, studies have begun on biofilm formation by Streptococcus pneumoniae, an important human pathogen, using a variety of in vitro model systems. The bacterial cells in these biofilms are held together by an extracellular matrix composed of DNA, proteins and, possibly, polysaccharide(s). Although neither the precise nature of these proteins nor the composition of the putative polysaccharide(s) is clear, it is known that choline‐binding proteins are required for successful biofilm formation. Further, many genes appear to be involved, although the role of each appears to vary when biofilms are produced in batch or continuous culture. Prophylactic and therapeutic measures need to be developed to fight S. pneumoniae biofilm formation. However, much care needs to be taken when choosing strains for such studies because different S. pneumoniae isolates can show remarkable genomic differences. Multispecies and in vivo biofilm models must also be developed to provide a more complete understanding of biofilm formation and maintenance.
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Affiliation(s)
- Mirian Domenech
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas and CIBER de Enfermedades Respiratorias, Madrid, Spain
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LuxS mediates iron-dependent biofilm formation, competence, and fratricide in Streptococcus pneumoniae. Infect Immun 2011; 79:4550-8. [PMID: 21875962 DOI: 10.1128/iai.05644-11] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During infection, Streptococcus pneumoniae exists mainly in sessile biofilms rather than in planktonic form, except during sepsis. The capacity to form biofilms is believed to be important for nasopharyngeal colonization as well as disease pathogenesis, but relatively little is known about the regulation of this process. Here, we investigated the effect of exogenous iron [Fe(III)] as well as the role of luxS (encoding S-ribosylhomocysteine lyase) on biofilm formation by S. pneumoniae D39. Fe(III) strongly enhanced biofilm formation at concentrations of ≥50 μM, while Fe(III) chelation with deferoxamine was inhibitory. Importantly, Fe(III) also upregulated the expression of luxS in wild-type D39. A luxS-deficient mutant (D39luxS) failed to form a biofilm, even with Fe(III) supplementation, whereas a derivative overexpressing luxS (D39luxS+) exhibited enhanced biofilm formation capacity and could form a biofilm without added Fe(III). D39luxS exhibited reduced expression of the major Fe(III) transporter PiuA, and the cellular [Fe(III)] was significantly lower than that in D39; in contrast, D39luxS+ had a significantly higher cellular [Fe(III)] than the wild type. The release of extracellular DNA, which is an important component of the biofilm matrix, also was directly related to luxS expression. Similarly, genetic competence, as measured by transformation frequency as well as the expression of competence genes comD, comX, comW, cglA, and dltA and the murein hydrolase cbpD, which is associated with fratricide-dependent DNA release, all were directly related to luxS expression levels and were further upregulated by Fe(III). Moreover, mutagenesis of cbpD blocked biofilm formation. We propose that competence, fratricide, and biofilm formation are closely linked in pneumococci, and that luxS is a central regulator of these processes. We also propose that the stimulatory effects of Fe(III) on all of these parameters are due to the upregulation of luxS expression, and that LuxS provides for a positive Fe(III)-dependent amplification loop by increasing iron uptake.
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The LuxS-dependent quorum-sensing system regulates early biofilm formation by Streptococcus pneumoniae strain D39. Infect Immun 2011; 79:4050-60. [PMID: 21825061 DOI: 10.1128/iai.05186-11] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is the leading cause of death in children worldwide and forms highly organized biofilms in the nasopharynx, lungs, and middle ear mucosa. The luxS-controlled quorum-sensing (QS) system has recently been implicated in virulence and persistence in the nasopharynx, but its role in biofilms has not been studied. Here we show that this QS system plays a major role in the control of S. pneumoniae biofilm formation. Our results demonstrate that the luxS gene is contained by invasive isolates and normal-flora strains in a region that contains genes involved in division and cell wall biosynthesis. The luxS gene was maximally transcribed, as a monocistronic message, in the early mid-log phase of growth, and this coincides with the appearance of early biofilms. Demonstrating the role of the LuxS system in regulating S. pneumoniae biofilms, at 24 h postinoculation, two different D39ΔluxS mutants produced ∼80% less biofilm biomass than wild-type (WT) strain D39 did. Complementation of these strains with luxS, either in a plasmid or integrated as a single copy in the genome, restored their biofilm level to that of the WT. Moreover, a soluble factor secreted by WT strain D39 or purified AI-2 restored the biofilm phenotype of D39ΔluxS. Our results also demonstrate that during the early mid-log phase of growth, LuxS regulates the transcript levels of lytA, which encodes an autolysin previously implicated in biofilms, and also the transcript levels of ply, which encodes the pneumococcal pneumolysin. In conclusion, the luxS-controlled QS system is a key regulator of early biofilm formation by S. pneumoniae strain D39.
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