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Damas MSF, Ferreira RL, Campanini EB, Soares GG, Campos LC, Laprega PM, Soares da Costa A, Freire CCDM, Pitondo-Silva A, Cerdeira LT, da Cunha AF, Pranchevicius MCDS. Whole genome sequencing of the multidrug-resistant Chryseobacterium indologenes isolated from a patient in Brazil. Front Med (Lausanne) 2022; 9:931379. [PMID: 35966843 PMCID: PMC9366087 DOI: 10.3389/fmed.2022.931379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 06/30/2022] [Indexed: 12/03/2022] Open
Abstract
Chryseobacterium indologenes is a non-glucose-fermenting Gram-negative bacillus. This emerging multidrug resistant opportunistic nosocomial pathogen can cause severe infections in neonates and immunocompromised patients. This study aimed to present the first detailed draft genome sequence of a multidrug-resistant C. indologenes strain isolated from the cerebrospinal fluid of an infant hospitalized at the Neonatal Intensive Care Unit of Brazilian Tertiary Hospital. We first analyzed the susceptibility of C. indologenes strain to different antibiotics using the VITEK 2 system. The strain demonstrated an outstanding resistance to all the antibiotic classes tested, including β-lactams, aminoglycosides, glycylcycline, and polymyxin. Next, C. indologenes was whole-genome-sequenced, annotated using Prokka and Rapid Annotation using Subsystems Technology (RAST), and screened for orthologous groups (EggNOG), gene ontology (GO), resistance genes, virulence genes, and mobile genetic elements using different software tools. The draft genome contained one circular chromosome of 4,836,765 bp with 37.32% GC content. The genomic features of the chromosome present numerous genes related to cellular processes that are essential to bacteria. The MDR C. indologenes revealed the presence of genes that corresponded to the resistance phenotypes, including genes to β-lactamases (blaIND–13, blaCIA–3, blaTEM–116, blaOXA–209, blaVEB–15), quinolone (mcbG), tigecycline (tet(X6)), and genes encoding efflux pumps which confer resistance to aminoglycosides (RanA/RanB), and colistin (HlyD/TolC). Amino acid substitutions related to quinolone resistance were observed in GyrA (S83Y) and GyrB (L425I and K473R). A mutation that may play a role in the development of colistin resistance was detected in lpxA (G68D). Chryseobacterium indologenes isolate harbored 19 virulence factors, most of which were involved in infection pathways. We identified 13 Genomic Islands (GIs) and some elements associated with one integrative and conjugative element (ICEs). Other elements linked to mobile genetic elements (MGEs), such as insertion sequence (ISEIsp1), transposon (Tn5393), and integron (In31), were also present in the C. indologenes genome. Although plasmids were not detected, a ColRNAI replicon type and the most resistance genes detected in singletons were identified in unaligned scaffolds. We provided a wide range of information toward the understanding of the genomic diversity of C. indologenes, which can contribute to controlling the evolution and dissemination of this pathogen in healthcare settings.
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Affiliation(s)
| | - Roumayne Lopes Ferreira
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | - Emeline Boni Campanini
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | | | | | - Pedro Mendes Laprega
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | - Andrea Soares da Costa
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | | | - André Pitondo-Silva
- Programa de Pós-graduação em Odontologia e Tecnologia Ambiental, Universidade de Ribeirão Preto, Ribeirão Preto, SP, Brazil
| | | | | | - Maria-Cristina da Silva Pranchevicius
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil
- Centro de Ciências Biológicas e da Saúde, Biodiversidade Tropical - BIOTROP, Universidade Federal de São Carlos, São Carlos, Brazil
- *Correspondence: Maria-Cristina da Silva Pranchevicius,
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van de Lagemaat M, Stockbroekx V, Geertsema-Doornbusch GI, Dijk M, Carniello V, Woudstra W, van der Mei HC, Busscher HJ, Ren Y. A Comparison of the Adaptive Response of Staphylococcus aureus vs. Streptococcus mutans and the Development of Chlorhexidine Resistance. Front Microbiol 2022; 13:861890. [PMID: 35694293 PMCID: PMC9186159 DOI: 10.3389/fmicb.2022.861890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/11/2022] [Indexed: 11/14/2022] Open
Abstract
Antimicrobials with nonselective antibacterial efficacy such as chlorhexidine can be effective in reducing biofilm, but bear the risk of inducing resistance in specific bacteria. In clinical practice, bacteria such as Staphylococcus aureus have been found resistant to chlorhexidine, but other bacteria, including Streptococcus mutans, have largely remained susceptible to chlorhexidine despite its widespread use in oral healthcare. Here, we aim to forward a possible reason as to why S. aureus can acquire resistance against chlorhexidine, while S. mutans remains susceptible to chlorhexidine. Measurement of surface-enhanced fluorescence indicated that chlorhexidine caused gradual, but irreversible deformation to adhering green fluorescent S. aureus due to irreparable damage to the cell wall. Concurrently, the metabolic activity of adhering staphylococci was higher than of planktonic bacteria, suggesting efflux mechanisms may have been activated upon cell wall deformation, impeding the buildup of a high chlorhexidine concentration in the cytoplasm and therewith stimulating the development of chlorhexidine resistance in S. aureus. Exposure of S. mutans to chlorhexidine caused immediate, but reversible deformation in adhering streptococci, indicative of rapid self-repair of cell wall damage done by chlorhexidine. Due to cell wall self-repair, S. mutans will be unable to effectively reduce the chlorhexidine concentration in the cytoplasm causing solidification of the cytoplasm. In line, no increased metabolic activity was observed in S. mutans during exposure to chlorhexidine. Therewith, self-repair is suicidal and prevents the development of a chlorhexidine-resistant progeny in S. mutans.
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Affiliation(s)
- Marieke van de Lagemaat
- University of Groningen and University Medical Center Groningen, Department of Orthodontics, Groningen, Netherlands
| | - Valerie Stockbroekx
- University of Groningen and University Medical Center Groningen, Department of Orthodontics, Groningen, Netherlands
| | - Gésinda I. Geertsema-Doornbusch
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Groningen, Netherlands
| | - Melissa Dijk
- University of Groningen and University Medical Center Groningen, Department of Orthodontics, Groningen, Netherlands
| | - Vera Carniello
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Groningen, Netherlands
| | - Willem Woudstra
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Groningen, Netherlands
| | - Henny C. van der Mei
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Groningen, Netherlands
- *Correspondence: Henny C. van der Mei,
| | - Henk J. Busscher
- University of Groningen and University Medical Center Groningen, Department of Biomedical Engineering, Groningen, Netherlands
| | - Yijin Ren
- University of Groningen and University Medical Center Groningen, Department of Orthodontics, Groningen, Netherlands
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Transcriptomic Stress Response in Streptococcus mutans following Treatment with a Sublethal Concentration of Chlorhexidine Digluconate. Microorganisms 2022; 10:microorganisms10030561. [PMID: 35336136 PMCID: PMC8950716 DOI: 10.3390/microorganisms10030561] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 01/27/2023] Open
Abstract
Despite the widespread use of antiseptics such as chlorhexidine digluconate (CHX) in dental practice and oral care, the risks of potential resistance toward these antimicrobial compounds in oral bacteria have only been highlighted very recently. Since the molecular mechanisms behind antiseptic resistance or adaptation are not entirely clear and the bacterial stress response has not been investigated systematically so far, the aim of the present study was to investigate the transcriptomic stress response in Streptococcus mutans after treatment with CHX using RNA sequencing (RNA-seq). Planktonic cultures of stationary-phase S. mutans were treated with a sublethal dose of CHX (125 µg/mL) for 5 min. After treatment, RNA was extracted, and RNA-seq was performed on an Illumina NextSeq 500. Differentially expressed genes were analyzed and validated by qRT-PCR. Analysis of differential gene expression following pathway analysis revealed a considerable number of genes and pathways significantly up- or downregulated in S. mutans after sublethal treatment with CHX. In summary, the expression of 404 genes was upregulated, and that of 271 genes was downregulated after sublethal CHX treatment. Analysis of differentially expressed genes and significantly regulated pathways showed regulation of genes involved in purine nucleotide synthesis, biofilm formation, transport systems and stress responses. In conclusion, the results show a transcriptomic stress response in S. mutans upon exposure to CHX and offer insight into potential mechanisms that may result in development of resistances.
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Genetic and physiological effects of subinhibitory concentrations of oral antimicrobial agents on Streptococcus mutans biofilms. Microb Pathog 2020; 150:104669. [PMID: 33278519 DOI: 10.1016/j.micpath.2020.104669] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/01/2020] [Accepted: 11/26/2020] [Indexed: 11/22/2022]
Abstract
Streptococcus mutans is the main etiological agent of dental caries because of its capacity to adhere to enamel structure and form biofilms. This study aimed to evaluate the effects of the anticariogenic agents - sodium fluoride (NaF) and chlorhexidine (CHX) - at levels below minimum inhibitory concentrations (sub-MICs) on the growth of planktonic cells and biofilms and on the expression of vicR and covR genes associated with the regulation of biofilm formation. MICs and minimum bactericidal concentrations (MBCs) of NaF and CHX were determined for S. mutans strains ATCC25175, UA159 and 3VF2. Growth curves were constructed for planktonic cells cultured in brain heart infusion (BHI) broth supplemented with NaF (0.125-0.75MIC) or CHX (0.25-0.75MIC). Biofilm formation assays were performed in microplates containing CHX or NaF at 0.5-1.0MIC and stained with violet crystal. Quantitative polymerase chain reaction determined the alterations in covR and vicR expression in cells exposed to antimicrobials at sub-MIC levels. NaF and CHX at sub-MIC levels affected the growth of planktonic cells of all three S. mutans strains, depending on the concentration tested. The biofilm formation in UA159 and 3VF2 was reduced by NaF at concentrations ≥0.5 MIC, while that of ATCC 25175 was reduced significantly irrespective of dose. In contrast, UA159 and 3VF2 biofilms were not affected by CHX at these levels, whereas those of ATCC 25175 were reduced significantly at all concentrations tested. Under sub-MIC conditions, CHX and (to a lesser degree) NaF increased vicR and covR expression in all three strains, although there were large differences between strains and treatment conditions employed. CHX and NaF at sub-MIC levels influence on the growth of S. mutans in planktonic and biofilm conditions and on transcript levels of biofilm-associated genes vicR and covR, in a dose-dependent manner.
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Khara P, Biswas S, Biswas I. Induction of clpP expression by cell-wall targeting antibiotics in Streptococcus mutans. MICROBIOLOGY-SGM 2020; 166:641-653. [PMID: 32416745 DOI: 10.1099/mic.0.000920] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Streptococcus mutans is one of the major bacteria of the human oral cavity that is associated with dental caries. The pathogenicity of this bacterium is attributed to its ability to rapidly respond and adapt to the ever-changing conditions of the oral cavity. The major player in this adaptive response is ClpP, an intracellular protease involved in degradation of misfolded proteins during stress responses. S. mutans encodes a single clpP gene with an upstream region uniquely containing multiple tandem repeat sequences (RSs). Here, we explored expression of clpP with respect to various stresses and report some new findings. First, we found that at sub-inhibitory concentration, certain cell-wall damaging antibiotics were able to induce clpP expression. Specifically, third- and fourth-generation cephalosporins that target penicillin-binding protein 3 (PBP3) strongly enhanced the clpP expression. However, induction of clpP was weak when the first-generation cephalosporins with lower affinity to PBP3 were used. Surprisingly, carbapenems, which primarily target PBP2, induced expression of clpP the least. Second, we found that a single RS element was capable of inducing clpP expression as efficiently as with the wild-type seven RS elements. Third, we found that the RS-element-mediated modulation of clpP expression was strain dependent, suggesting that specific host factors might be involved in the transcription. And finally, we observed that ClpP regulates its own expression, as the expression of clpP-gusA was higher in a clpP-deficient mutant. This suggests that ClpP is involved in the degradation of activator(s) involved in its own transcription.
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Affiliation(s)
- Pratick Khara
- Present address: Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, Texas, USA.,Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
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Damé-Teixeira N, Deng D, Do T. Streptococcus mutans transcriptome in the presence of sodium fluoride and sucrose. Arch Oral Biol 2019; 102:186-192. [PMID: 31071638 DOI: 10.1016/j.archoralbio.2019.04.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 04/27/2019] [Accepted: 04/29/2019] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Considering the diverse mechanisms by which fluoride could affect oral bacteria, this study evaluated the effect of sodium fluoride onStreptococcus mutans transcriptome in the presence of sucrose. METHODS S. mutans UA159 was cultured in 3 different types of media: medium control[TY], sucrose control[TY_S], and sodium fluoride sucrose test[TY_S_NaF]. Triplicates of each group were sampled at exponential phase 3 h after inoculation, total RNA was isolated, mRNA enriched and cDNA paired-end sequenced (Illumina Hi-Seq2500). RESULTS Genes related toS. mutans adhesion(gtfB and gtfC), acidogenicity and sugar transport were up-regulated in the presence of sucrose(TY_S) and sucrose/fluoride(TY_S_NaF), whereas gene dltA, D-alanine-activating enzyme, which is related to regulation of non-PTS sugar internalization was down-regulated. Up-regulation of the scrA gene and the PTS fructose-and mannose system, as well as functions such as those involved in stress and defence responses and peptidases; and down-regulation of lacACDG and pyruvate formate-lyase were observed in the TY_S_NaF group, as compared to TY_S group. CONCLUSIONS The presence of NaF has decreased the overall gene expression level inS. mutans. However, its major effect seems to be the inducing of expression of genes involved in some PEP:PTS systems and other metabolic transporters which imply specific cellular internalisation of sugars.
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Affiliation(s)
- Naile Damé-Teixeira
- Department of Dentistry, University of Brasilia, Brasilia, Distrito Federal, Brazil
| | - Dongmei Deng
- Department of Preventive Dentistry, Academic Center for Dentistry Amsterdam, University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Thuy Do
- Division of Oral Biology, School of Dentistry, University of Leeds, Leeds, West Yorkshire, United Kingdom.
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Edlund A, Yang Y, Yooseph S, He X, Shi W, McLean JS. Uncovering complex microbiome activities via metatranscriptomics during 24 hours of oral biofilm assembly and maturation. MICROBIOME 2018; 6:217. [PMID: 30522530 PMCID: PMC6284299 DOI: 10.1186/s40168-018-0591-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 11/06/2018] [Indexed: 05/11/2023]
Abstract
BACKGROUND Dental plaque is composed of hundreds of bacterial taxonomic units and represents one of the most diverse and stable microbial ecosystems associated with the human body. Taxonomic composition and functional capacity of mature plaque is gradually shaped during several stages of community assembly via processes such as co-aggregation, competition for space and resources, and by bacterially produced reactive agents. Knowledge on the dynamics of assembly within complex communities is very limited and derives mainly from studies composed of a limited number of bacterial species. To fill current knowledge gaps, we applied parallel metagenomic and metatranscriptomic analyses during assembly and maturation of an in vitro oral biofilm. This model system has previously demonstrated remarkable reproducibility in taxonomic composition across replicate samples during maturation. RESULTS Time course analysis of the biofilm maturation was performed by parallel sampling every 2-3 h for 24 h for both DNA and RNA. Metagenomic analyses revealed that community taxonomy changed most dramatically between three and six hours of growth when pH dropped from 6.5 to 5.5. By applying comparative metatranscriptome analysis we could identify major shifts in overall community activities between six and nine hours of growth when pH dropped below 5.5, as 29,015 genes were significantly up- or down- expressed. Several of the differentially expressed genes showed unique activities for individual bacterial genomes and were associated with pyruvate and lactate metabolism, two-component signaling pathways, production of antibacterial molecules, iron sequestration, pH neutralization, protein hydrolysis, and surface attachment. Our analysis also revealed several mechanisms responsible for the niche expansion of the cariogenic pathogen Lactobacillus fermentum. CONCLUSION It is highly regarded that acidic conditions in dental plaque cause a net loss of enamel from teeth. Here, as pH drops below 5.5 pH to 4.7, we observe blooms of cariogenic lactobacilli, and a transition point of many bacterial gene expression activities within the community. To our knowledge, this represents the first study of the assembly and maturation of a complex oral bacterial biofilm community that addresses gene level functional responses over time.
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Affiliation(s)
- Anna Edlund
- Genomic Medicine Group, J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92137, USA.
| | - Youngik Yang
- National Marine Biodiversity Institute of Korea, 75, Jansang-ro 101beon-gil, Janghang-eup, Seocheon-gun, Chungcheongnam-do, 33662, Korea
| | - Shibu Yooseph
- Department of Computer Science, University of Central Florida, 4328 Scorpius Street, Orlando, FL, 32816, USA
| | - Xuesong He
- The Forsyth Institute, Cambridge, MA, 02142, USA
| | - Wenyuan Shi
- The Forsyth Institute, Cambridge, MA, 02142, USA
| | - Jeffrey S McLean
- Department of Periodontics, University of Washington, Seattle, WA, 98195, USA.
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Sousa-Silva M, Simões M, Melo L, Machado I. Pseudomonas fluorescens tolerance to benzyldimethyldodecyl ammonium chloride: Altered phenotype and cross-resistance. J Glob Antimicrob Resist 2018; 15:188-195. [PMID: 30026133 DOI: 10.1016/j.jgar.2018.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/22/2018] [Accepted: 07/08/2018] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVES Benzyldimethyldodecyl ammonium chloride (BDMDAC) is a quaternary ammonium compound (QAC) with bactericidal action that is used as an active molecule in detergent formulations. Pseudomonas fluorescens is a Gram-negative bacterium with versatile metabolism that is frequently present in biofilms on industrial surfaces. This work reports P. fluorescens adaptation to BDMDAC and subsequent concurrent reduced susceptibility to the QAC benzalkonium chloride (BAC) and the antimicrobial ciprofloxacin (CIP). METHODS Stepwise adaptation to increasing concentrations of BDMDAC was easily achieved and caused changes in the bacterial phenotype of P. fluorescens. Adaptation was evaluated through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determination and was subsequently confirmed by time-kill curves. Biofilm phenotype (biomass and number of cells) was characterised for the adapted and reference strains after treatment with BDMDAC, BAC and CIP. RESULTS Susceptibility to BAC and CIP was reduced in adapted P. fluorescens. Biofilms developed by the adapted strain had 20% more mass and a higher number of bacteria (2 log). CONCLUSIONS This study revealed that exposure to sublethal concentrations of BDMDAC may select tolerant strains to that product as well as to related products and unrelated antimicrobial agents.
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Affiliation(s)
- Maria Sousa-Silva
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, s/n, 4200-465 Porto, Portugal
| | - Manuel Simões
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, s/n, 4200-465 Porto, Portugal
| | - Luís Melo
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, s/n, 4200-465 Porto, Portugal
| | - Idalina Machado
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, s/n, 4200-465 Porto, Portugal.
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Liu C, Niu Y, Zhou X, Zheng X, Wang S, Guo Q, Li Y, Li M, Li J, Yang Y, Ding Y, Lamont RJ, Xu X. Streptococcus mutans copes with heat stress by multiple transcriptional regulons modulating virulence and energy metabolism. Sci Rep 2015; 5:12929. [PMID: 26251057 PMCID: PMC4528225 DOI: 10.1038/srep12929] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 07/14/2015] [Indexed: 02/05/2023] Open
Abstract
Dental caries is closely associated with the virulence of Streptococcus mutans. The virulence expression of S. mutans is linked to its stress adaptation to the changes in the oral environment. In this work we used whole-genome microarrays to profile the dynamic transcriptomic responses of S. mutans during physiological heat stress. In addition, we evaluated the phenotypic changes, including, eDNA release, initial biofilm formation, extracellular polysaccharides generation, acid production/acid tolerance, and ATP turnover of S. mutans during heat stress. There were distinct patterns observed in the way that S. mutans responded to heat stress that included 66 transcription factors for the expression of functional genes being differentially expressed. Especially, response regulators of two component systems (TCSs), the repressors of heat shock proteins and regulators involved in sugar transporting and metabolism co-ordinated to enhance the cell’s survival and energy generation against heat stress in S. mutans.
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Affiliation(s)
- Chengcheng Liu
- 1] State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [2] Department of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [3] Center for Oral Health and Systemic Disease, School of Dentistry, University of Louisville, Louisville, Kentucky, USA
| | - Yulong Niu
- Key Lab of Bio-resources and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | - Xuedong Zhou
- 1] State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [2] Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Xin Zheng
- 1] State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [2] Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Shida Wang
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Qiang Guo
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Yuqing Li
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Mingyun Li
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Jiyao Li
- 1] State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [2] Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Yi Yang
- Key Lab of Bio-resources and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | - Yi Ding
- 1] State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [2] Department of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
| | - Richard J Lamont
- Center for Oral Health and Systemic Disease, School of Dentistry, University of Louisville, Louisville, Kentucky, USA
| | - Xin Xu
- 1] State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China [2] Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China
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Hou XH, Zhang JQ, Song XY, Ma XB, Zhang SY. Contribution of ClpP to stress tolerance and virulence properties of Streptococcus mutans. J Basic Microbiol 2014; 54:1222-32. [PMID: 24979467 DOI: 10.1002/jobm.201300747] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 03/18/2014] [Indexed: 11/06/2022]
Abstract
Abilities to tolerate environmental stresses and to form biofilms on teeth surface are key virulence attributes of Streptococcus mutans, the primary causative agent of human dental caries. ClpP, the chief intracellular protease of S. mutans, along with ATPases degrades altered proteins that might be toxic for bacteria, and thus plays important roles in stress response. To further understand the roles of ClpP in stress response of S. mutans, a ClpP deficient strain was constructed and used for general stress tolerance, autolysis, mutacins production, and virulence assays. Here, we demonstrated that inactivation of ClpP in S. mutans resulted in a sensitive phenotype to several environmental stresses, including acid, cold, thermal, and oxidative stresses. The ClpP deficient strain displayed slow growth rates, poor growth yields, formation of long chains, increased clumping in broth, and reduced capacity to form biofilms in presence of glucose. Mutacins production and autolysis of S. mutans were also impaired by mutation of clpP. Animals study showed that clpP mutation increased virulence of S. mutans but not significant. However, enhanced abilities to survive lethal acid and to form biofilm in sucrose were observed in ClpP deficient strain. Our findings revealed a broad impact of ClpP on several virulence properties of S. mutans and highlighted the relevance of ClpP proteolysis with progression of diseases caused by S. mutans.
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Affiliation(s)
- Xiang-Hua Hou
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, Xiamen, China
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Carvalho A, Pelaez-Vargas A, Gallego-Perez D, Grenho L, Fernandes M, De Aza A, Ferraz M, Hansford D, Monteiro F. Micropatterned silica thin films with nanohydroxyapatite micro-aggregates for guided tissue regeneration. Dent Mater 2012; 28:1250-60. [DOI: 10.1016/j.dental.2012.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 08/12/2012] [Accepted: 09/07/2012] [Indexed: 11/29/2022]
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Hannig C, Kirsch J, Al-Ahmad A, Kensche A, Hannig M, Kümmerer K. Do edible oils reduce bacterial colonization of enamel in situ? Clin Oral Investig 2012; 17:649-58. [PMID: 22552590 DOI: 10.1007/s00784-012-0734-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 04/09/2012] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Edible oils are an empiric approach for the prevention of oral diseases. The present in situ study investigated the effect of edible oils on initial bacterial colonization of enamel surfaces. METHODS AND MATERIALS Initial biofilm formation was performed on enamel specimens mounted on maxillary splints and carried by eight subjects. After 1 min of pellicle formation, rinses with safflower oil, olive oil and linseed oil were performed for 10 min. Application of chlorhexidine for 1 min served as positive control. Afterwards, the slabs were carried for 8 h overnight. Samples carried for 8 h without any rinse served as negative controls. The amount of adherent bacteria was determined by DAPI staining (4',6-diamidino-2-phenylindole) and live-dead staining (BacLight). Additionally, determination of colony forming units was performed after desorption of the bacteria. TEM evaluation was carried out after application of the rinses. RESULTS The number of adherent bacteria on control samples was 6.1 ± 8.1 × 10(5)/cm(2) after 8 h (DAPI). Fluorescence microscopic data from DAPI staining and live-dead staining as well as from the determination of CFU revealed no significant effects of rinsing with oils on the amount of adherent bacteria compared to the non-rinsed control samples. However, with chlorhexidine a significant reduction in the number of bacteria by more than 85 % was achieved (DAPI, chlorhexidine: 8.2 ± 17.1 × 10(4)/cm(2)). The ratio of viable to dead bacteria was almost equal (1:1) irrespective of the rinse adopted as recorded with BacLight. TEM indicated accumulation of oil micelles at the pellicle's surface and modification of its ultrastructure. CONCLUSION Rinses with edible oils have no significant impact on the initial pattern and amount of bacterial colonization on enamel over 8 h. CLINICAL RELEVANCE Rinses with edible oils cannot be recommended for efficient reduction of oral biofilm formation.
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Affiliation(s)
- Christian Hannig
- Clinic of Operative Dentistry, Medical Faculty Carl Gustav Carus, TU Dresden, Fetscherstr. 74, 01307 Dresden, Germany.
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Xue X, Li J, Wang W, Sztajer H, Wagner-Döbler I. The global impact of the delta subunit RpoE of the RNA polymerase on the proteome of Streptococcus mutans. Microbiology (Reading) 2012; 158:191-206. [DOI: 10.1099/mic.0.047936-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Xiaoli Xue
- Research Group Microbial Communication, Division of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, D-38124 Braunschweig, Germany
| | - Jinshan Li
- Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, 100101 Beijing, PR China
- Institute of Bioprocess and Biosystems Engineering, Technical University Hamburg-Harburg, Denickestr. 15, D-21071 Hamburg, Germany
| | - Wei Wang
- Institute of Bioprocess and Biosystems Engineering, Technical University Hamburg-Harburg, Denickestr. 15, D-21071 Hamburg, Germany
| | - Helena Sztajer
- Research Group Microbial Communication, Division of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, D-38124 Braunschweig, Germany
| | - Irene Wagner-Döbler
- Research Group Microbial Communication, Division of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, D-38124 Braunschweig, Germany
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Kajfasz JK, Abranches J, Lemos JA. Transcriptome analysis reveals that ClpXP proteolysis controls key virulence properties of Streptococcus mutans. MICROBIOLOGY-SGM 2011; 157:2880-2890. [PMID: 21816882 DOI: 10.1099/mic.0.052407-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ClpXP proteolytic complex is critical for maintaining cellular homeostasis, as well as expression of virulence properties. However, with the exception of the Spx global regulator, the molecular mechanisms by which the ClpXP complex exerts its influence in Streptococcus mutans are not well understood. Here, microarray analysis was used to provide novel insights into the scope of ClpXP proteolysis in S. mutans. In a ΔclpP strain, 288 genes showed significant changes in relative transcript amounts (P≤0.001, twofold cut-off) as compared with the parent. Similarly, 242 genes were differentially expressed by a ΔclpX strain, 113 (47 %) of which also appeared in the ΔclpP microarrays. Several genes associated with cell growth were downregulated in both mutants, consistent with the slow-growth phenotype of the Δclp strains. Among the upregulated genes were those encoding enzymes required for the biosynthesis of intracellular polysaccharides (glg genes) and malolactic fermentation (mle genes). Enhanced expression of glg and mle genes in ΔclpP and ΔclpX strains correlated with increased storage of intracellular polysaccharide and enhanced malolactic fermentation activity, respectively. Expression of several genes known or predicted to be involved in competence and mutacin production was downregulated in the Δclp strains. Follow-up transformation efficiency and deferred antagonism assays validated the microarray data by showing that competence and mutacin production were dramatically impaired in the Δclp strains. Collectively, our results reveal the broad scope of ClpXP regulation in S. mutans homeostasis and identify several virulence-related traits that are influenced by ClpXP proteolysis.
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Affiliation(s)
- Jessica K Kajfasz
- Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Jacqueline Abranches
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - José A Lemos
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA.,Center for Oral Biology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Resazurin metabolism assay for root canal disinfectant evaluation on dual-species biofilms. J Endod 2010; 37:31-5. [PMID: 21146072 DOI: 10.1016/j.joen.2010.09.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 09/08/2010] [Accepted: 09/19/2010] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Endodontic infections are caused by polymicrobial biofilms. Therefore, novel root canal disinfectants should be evaluated not only on single-species biofilms but also on dual- or mixed-species biofilms. A simple, high-throughput assay is urgently needed for this. In this study, the application of the resazurin metabolism assay was investigated for the evaluation of a root canal disinfectant on dual-species biofilms. METHODS Enterococcus faecalis with or without Streptococcus mutans in biofilms were formed in an active attachment biofilm model for 24 hours. Subsequently, the biofilms were treated with various concentrations of NaOCl for 1 minute. After resazurin metabolism by both organisms was confirmed, treatment efficacies using 0.0016% resazurin were evaluated. RESULTS During NaOCl treatments, resazurin metabolism displays a clear dose response, not only in single-species E. faecalis (or S. mutans) biofilms but also in dual-species biofilms. Notably, the assay revealed that the resistance of dual-species biofilms to NaOCl was 30-fold higher than in single-species E. faecalis biofilms. Viability counts on a selected NaOCl treatment (0.004%) confirmed this result and showed the increased resistance of E. faecalis in dual-species biofilms. CONCLUSIONS Clearly, the high-throughput and low cost resazurin metabolism assay has a great potential for testing novel root canal antimicrobial agents in mixed-species biofilms.
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Paula VAC, Modesto A, Santos KRN, Gleiser R. Antimicrobial effects of the combination of chlorhexidine and xylitol. Br Dent J 2010; 209:E19. [DOI: 10.1038/sj.bdj.2010.887] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2009] [Indexed: 11/09/2022]
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Two Spx proteins modulate stress tolerance, survival, and virulence in Streptococcus mutans. J Bacteriol 2010; 192:2546-56. [PMID: 20233935 DOI: 10.1128/jb.00028-10] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Previous work suggested that the underlying mechanisms by which the Streptococcus mutans ClpXP protease affects virulence traits are associated with accumulation of two orthologues of the Spx regulator, named SpxA and SpxB. Here, a thorough characterization of strains lacking the spx genes (Delta spxA, Delta spxB, and Delta spxA Delta spxB) revealed that Spx, indeed, participates in the regulation of processes associated with S. mutans pathogenesis. The Delta spxA strain displayed impaired ability to grow under acidic and oxidative stress conditions and had diminished long-term viability at low pH. Although the Delta spxB strain did not show any inherent stress-sensitive phenotype, the phenotypes observed in Delta spxA were more pronounced in the Delta spxA Delta spxB double mutant. By using two in vivo models, we demonstrate for the first time that Spx is required for virulence in a gram-positive pathogen. Microarrays confirmed the global regulatory role of SpxA and SpxB. In particular, SpxA was shown to positively regulate genes associated with oxidative stress, a finding supported by enzymatic assays. SpxB had a secondary role in regulation of oxidative stress genes but appeared to play a larger role in controlling processes associated with cell wall homeostasis. Given the high degree of conservation between Spx proteins of low-GC gram-positive bacteria, these results are likely to have broad implications.
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Kang KH, Lee JS, Yoo M, Jin I. The influence of HtrA expression on the growth of Streptococcus mutans during acid stress. Mol Cells 2010; 29:297-304. [PMID: 20387036 DOI: 10.1007/s10059-010-0036-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 11/25/2009] [Accepted: 11/25/2009] [Indexed: 11/26/2022] Open
Abstract
When proteins are damaged under stresses conditions, these proteins are either refolded or degraded by quality control system of molecular chaperones and protease. High-temperature requirement A (htrA) is of particular interest because it can perform the roles of both protease and a chaperone. HtrA plays an important role in maintaining the physiological homeostasis of bacteria against environmental stress such as elevated temperature, oxidative and osmotic stress. Inactivation of htrA genes can thus restrict the survival ability of bacteria. These observations suggested that htrA might be responsible for acid tolerance of Streptococcus mutans. In this study, we have generated an htrA mutant and an htrA-complemented strain of S. mutans K7 isolated from a Korean in order to investigate the role of htrA in growth under acidic conditions. In terms of growth under cidic conditions, the htrA mutant exhibited 20% to 23% lower growth than the control group. In addition, glucosyltransferase B and glucosyltransferase C expression levels significantly decreased. When the htrA expression level was restored by adding the htrA gene to the htrA mutant strain, the normal growth phenotype was restored under acid stress. Further, similar results were obtained for S. mutans UA159. Thus, htrA in S. mutans K7, as well as S. mutans UA159, can be concluded to play an important role during acid stress.
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Affiliation(s)
- Kyung-hee Kang
- Department of Dental Hygiene, Konyang University, Daejeon, 302-718, Korea
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ClpP of Streptococcus mutans differentially regulates expression of genomic islands, mutacin production, and antibiotic tolerance. J Bacteriol 2009; 192:1312-23. [PMID: 20038588 DOI: 10.1128/jb.01350-09] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Streptococcus mutans is the primary etiological agent of human dental caries and, at times, of infective endocarditis. Within the oral cavity, the pathogen is subjected to conditions of stress. A well-conserved protein complex named ClpP (caseinolytic protease) plays a vital role in adaptation under stress conditions. To gain a better understanding of the global role of the ClpP protease in cellular homeostasis, a transcriptome analysis was performed using a DeltaclpP mutant strain. The expression levels of more than 100 genes were up- or downregulated in the DeltaclpP mutant compared to the wild type. Notably, the expression of genes in several genomic islands, such as TnSmu1 and TnSmu2, was differentially modulated in the DeltaclpP mutant strain. ClpP deficiency also increased the expression of genes associated with a putative CRISPR locus. Furthermore, several stress-related genes and genes encoding bacteriocin-related peptides and many transcription factors were also found to be altered in the DeltaclpP mutant strain. A comparative analysis of the two-dimensional protein profile of the wild type and the DeltaclpP mutant strains showed altered protein profiles. Comparison of the transcriptome data with the proteomic data identified four common gene products, suggesting that the observed altered protein expression of these genes could be due to altered transcription. The results presented here indicate that ClpP-mediated proteolysis plays an important global role in the regulation of several important traits in this pathogen.
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Hannig C, Sorg J, Spitzmüller B, Hannig M, Al-Ahmad A. Polyphenolic beverages reduce initial bacterial adherence to enamel in situ. J Dent 2009; 37:560-6. [PMID: 19394124 DOI: 10.1016/j.jdent.2009.03.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 03/23/2009] [Accepted: 03/24/2009] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Polyphenols are antibacterial and anti-oxidative natural agents. The present in situ study aimed to investigate the effect of different polyphenolic beverages on initial bacterial adherence to enamel in the oral cavity. METHODS Initial biofilm formation was performed on bovine enamel specimens mounted buccally on individual upper jaw splints and carried by six subjects. After 1 min of pellicle formation, oral rinses with black tea, green tea, grape juice, Cistus tea or red wine were performed for 10 min. Afterwards the slabs were carried for another 19 or 109 min, respectively. Samples exposed to the oral fluids for 30 and 120 min served as controls. Following intraoral exposure, the slabs were rinsed with saline solution. The amount of adherent bacteria was determined with DAPI-staining (4',6-diamidino-2-phenylindole) and with fluorescence-in situ hybridization (FISH) of eubacteria and streptococci. RESULTS Rinses with all beverages reduced the amount of detectable bacteria. Lowest number of adherent bacteria was found following rinses with red wine, Cistus tea and black tea as measured with DAPI (up to 66% reduction of adherent bacteria vs. controls). Also FISH revealed significant impact of most tested beverages. CONCLUSIONS Rinses with certain polyphenolic beverages as well as consumption of these foodstuffs may contribute to prevention of biofilm induced diseases in the oral cavity.
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Affiliation(s)
- Christian Hannig
- Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany.
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Novel metabolic activity indicator in Streptococcus mutans biofilms. J Microbiol Methods 2009; 77:67-71. [DOI: 10.1016/j.mimet.2009.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 12/17/2008] [Accepted: 01/12/2009] [Indexed: 11/23/2022]
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Moser C, Van Gennip M, Bjarnsholt T, Jensen PØ, Lee B, Hougen HP, Calum H, Ciofu O, Givskov M, Molin S, Høiby N. Novel experimental Pseudomonas aeruginosa lung infection model mimicking long-term host-pathogen interactions in cystic fibrosis. APMIS 2009; 117:95-107. [PMID: 19239431 PMCID: PMC2774147 DOI: 10.1111/j.1600-0463.2008.00018.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The dominant cause of premature death in patients suffering from cystic fibrosis (CF) is chronic lung infection with Pseudomonas aeruginosa. The chronic lung infection often lasts for decades with just one clone. However, as a result of inflammation, antibiotic treatment and different niches in the lungs, the clone undergoes significant genetic changes, resulting in diversifying geno- and phenotypes. Such an adaptation may generate different host responses. To experimentally reflect the year-long chronic lung infection in CF, groups of BALB/c mice were infected with clonal isolates from different periods (1980, 1988, 1997, 1999 and 2003) of the chronic lung infection of one CF patient using the seaweed alginate embedment model. The results showed that the non-mucoid clones reduced their virulence over time, resulting in faster clearing of the bacteria from the lungs, improved pathology and reduced pulmonary production of macrophage inflammatory protein-2 (MIP-2) and granulocyte colony-stimulating factor (G-CSF). In contrast, the mucoid clones were more virulent and virulence increased with time, resulting in impaired pulmonary clearing of the latest clone, severe inflammation and increased pulmonary MIP-2 and G-CSF production. In conclusion, adaptation of P. aeruginosa in CF is reflected by changed ability to establish lung infection and results in distinct host responses to mucoid and non-mucoid phenotypes.
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Affiliation(s)
- Claus Moser
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
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Role of Clp proteins in expression of virulence properties of Streptococcus mutans. J Bacteriol 2009; 191:2060-8. [PMID: 19181818 DOI: 10.1128/jb.01609-08] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mutational analysis revealed that members of the Clp system, specifically the ClpL chaperone and the ClpXP proteolytic complex, modulate the expression of important virulence attributes of Streptococcus mutans. Compared to its parent, the DeltaclpL strain displayed an enhanced capacity to form biofilms in the presence of sucrose, had reduced viability, and was more sensitive to acid killing. The DeltaclpP and DeltaclpX strains displayed several phenotypes in common: slow growth, tendency to aggregate in culture, reduced autolysis, and reduced ability to grow under stress, including acidic pH. Unexpectedly, the DeltaclpP and DeltaclpX mutants were more resistant to acid killing and demonstrated enhanced viability in long-term survival assays. Biofilm formation by the DeltaclpP and DeltaclpX strains was impaired when grown in glucose but enhanced in sucrose. In an animal study, the average number of S. mutans colonies recovered from the teeth of rats infected with the DeltaclpP or DeltaclpX strain was slightly lower than that of the parent strain. In Bacillus subtilis, the accumulation of the Spx global regulator, a substrate of ClpXP, has accounted for the DeltaclpXP phenotypes. Searching the S. mutans genome, we identified two putative spx genes, designated spxA and spxB. The inactivation of either of these genes bypassed phenotypes of the clpP and clpX mutants. Western blotting demonstrated that Spx accumulates in the DeltaclpP and DeltaclpX strains. Our results reveal that the proteolysis of ClpL and ClpXP plays a role in the expression of key virulence traits of S. mutans and indicates that the underlying mechanisms by which ClpXP affect virulence traits are associated with the accumulation of two Spx orthologues.
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Lemos JA, Burne RA. A model of efficiency: stress tolerance by Streptococcus mutans. MICROBIOLOGY-SGM 2008; 154:3247-3255. [PMID: 18957579 DOI: 10.1099/mic.0.2008/023770-0] [Citation(s) in RCA: 210] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The complete genome sequence of Streptococcus mutans, a bacterial pathogen commonly associated with human dental caries, was published in 2002. The streamlined genome (2.03 Mb) revealed an organism that is well adapted to its obligately host-associated existence in multispecies biofilms on tooth surfaces: a dynamic environment that undergoes rapid and substantial fluctuations. However, S. mutans lacks many of the sensing systems and alternative sigma factors that bacteria often use to coordinate gene expression in response to stress and changes in their environment. Over the past 7 years, functional genomics and proteomics have enhanced our understanding of how S. mutans has integrated the stress regulon and global transcriptional regulators to coordinate responses to environmental fluctuations with modulation of virulence in a way that ensures persistence in the oral cavity and capitalizes on conditions that are favourable for the development of dental caries. Here, we highlight advances in dissection of the stress regulon of S. mutans and its intimate interrelationship with pathogenesis.
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Affiliation(s)
- José A Lemos
- Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Robert A Burne
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA
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