1000 resultados para STREPTOCOCCUS PYOGENES


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Group A Streptococcus is a Gram-positive human pathogen able to colonize both upper respiratory tract and skin. GAS is responsible for several acute diseases and autoimmune sequelae that account for half a million deaths worldwide every year (Cunningham et al., 2000). As other bacteria, GAS infections requires the capacity of the pathogen to adhere to host tissues and to form cell aggregates. The ability to persist in distinct host niches like the throat and the skin and to trigger infections is associated with the expression of different GAS virulence factors. GAS pili has been described as important virulence factors encoded by different FCT-operon regions. Based on this information, we decided to study the possible effect of environmental conditions that could regulate the pili expression. In this study we reported the influence of pH environment variations in biofilm formation for strains pertaining to a panel of different GAS FCT-types. The biofilm formation was promoted, excepted in the FCT-1 strains, by a changing in pH from physiological to acidic condition of growth in in vitro biofilm assay. By analyzing the possible association between biofilm formation and pH dependence, we have found that in FCT-2 and FCT-3 strains, the biofilm is promoted by pH reduction leading to an increase of pili expression. These data confirmed a direct link between pH dependent pilus expression and biofilm formation in GAS. As pili are a multi component structure we decided to investigate the functional role of one of its subunits, the AP-1 protein. AP-1 is highly conserved through the different FCT-types and suggests a possible essential role for the pili function. We focused our attention on the AP-1 protein encoded by the FCT-1 strains (M6). In particular this AP-1 protein contains the von Willebrand Factor A (VWFA) domain, which share an homology with the human VWFA domain that has been reported to be involved in adhesion process. We have demonstrated that the AP-1 protein binds to human epithelial cells by its VWFA domain, whereas the biofilm formation is mediated by the N-terminal region of AP-1 protein. Moreover, analyzing the importance of AP-1 in in vivo experiments we found a major capacity of tissue dissemination for the wild-type strain compared to the isogenic AP-1 deletion mutant. Pili have been also reported as potential vaccine candidates against Gram positive bacteria. For these reason we decided to investigate the relationship between cross reaction of sera raised against different GAS and GBS pilin subunits and the presence of a conserved Cna_B domain, in different pilin components. Our idea was to investigate if, using pilus conserved domains, a broad coverage vaccine against streptococcal infection could be possible.

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The 1,852,442-bp sequence of an M1 strain of Streptococcus pyogenes, a Gram-positive pathogen, has been determined and contains 1,752 predicted protein-encoding genes. Approximately one-third of these genes have no identifiable function, with the remainder falling into previously characterized categories of known microbial function. Consistent with the observation that S. pyogenes is responsible for a wider variety of human disease than any other bacterial species, more than 40 putative virulence-associated genes have been identified. Additional genes have been identified that encode proteins likely associated with microbial “molecular mimicry” of host characteristics and involved in rheumatic fever or acute glomerulonephritis. The complete or partial sequence of four different bacteriophage genomes is also present, with each containing genes for one or more previously undiscovered superantigen-like proteins. These prophage-associated genes encode at least six potential virulence factors, emphasizing the importance of bacteriophages in horizontal gene transfer and a possible mechanism for generating new strains with increased pathogenic potential.

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In our country there is a variety of medicinal plants some of them without scientific studies and little investigation that is the case of the species Croton elegans, the ethnobotanical use of it allows us to deduce some antimicrobial activity, this being the fundament that determined the essay on some respiratory disease causing bacteria such as: Staphylococcus aureus ATCC 25923 Streptococcus pneumoniae ATCC (49619), Streptococcus mutans ATCC (25175) y Streptococcus pyogenes ATCC (19615). Maceration with dry crushed leaves in 90% alcohol was performed for two days and a fluid extract was obtained in two concentrations 25% and 50%. With the extracts, phytochemical qualitative and antimicrobial activity tests were performed by the modified well diffusion method. The obtained results in the phytochemical tests show presence of resins, amino acids, flavonoids, catechins, alkaloids, quinones. The antibacterial activity tests on either extract concentrations showed no activity against Staphylococcus aureus ATCC 25923, in the case of Streptococcus pneumoniae ATCC 49619, both concentrations presented with inhibitory activity, the statistical analysis determines that a 50% concentration is more effective with a halo of 11.74 mm, with Streptococcus mutans ATCC 25175, both concentrations had inhibitory activity, but statistically neither concentration showed more effectiveness above the other, in Streptococcus pyogenes ATCC 19615, both concentrations had inhibitory activity, statistically concentration 25% was more effective with a halo of 15.16 mm.

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The main objective of this project work is to evaluate the antibacterial activity of the essential oil and fluid extract of Oreopanax ecuadorensis Seeman. It was used the essential oil of the vegetal specie obtained by duct diffusion and they were performed dilutions of the same with DMSO, working with the next concentrations (5%, 2.5% and 1.25%), also was evaluated the activity of the fluid extract at 25% of concentration performed by percolation. The duct diffusion technique was made with different concentration levels of essential oil and only one concentration of fluid extract compared to: Staphylococcus aureus ATCC: 25923, Streptococcus mutans ATCC: 25175, Streptococcus pneumoniae ATCC: 49619 y Streptococcus pyogenes ATCC: 19615, those bacteria considered as representative as principal pathogens of respiratory diseases. Based on the results and the statistical analysis it could be concluded that Oreopanax ecuadorensis Seeman, with the 25% of concentration by the extract presented inhibitory activity in front of Streptococcus pyogenes ATCC 19615 with 12.1 mm, follow of Streptococcus mutans ATCC 25175 with 10.9 mm and 10.4 mm to Streptococcus pneumoniae ATCC 49619, while not evidenced inhibitory activity in front of Staphylococcus aureus ATCC 25923. Whereas the essential oil presents in the 5%, 2.5% and 1.25% concentrations values of 6 mm of diameter of inhibition to: Staphylococcus aureus ATCC 25923, Streptococcus mutans ATCC 25175, Streptococcus pneumoniae ATCC 49619, and y Streptococcus pyogenes ATCC 19615.

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Ecuador has a wide biodiversity of medicinal plants from different regions of the country, most of medicinal plants are used as such based on ancestral knowledge rather not have scientific knowledge of their medicinal properties although there are few studies on the Andean plants Ecuador, is not scientific information on the antibacterial activity of sunfo (Clinopodium nubigenum (Kunth) Kuntze.). In this experimental work the antimicrobial activity of essential oil sunfo. Was determined against four bacteria causing respiratory diseases, sunfo was collected in the moors of the parish of Pintag in the National Herbarium it was certified that it was Clinopodium nubigenum (Kunth) Kuntz., for the extraction of essential oil distillation technique was used by steam. Determining the antimicrobial activity of the oil it was tested by in vitro susceptibility tests diffusion wells using six concentrations of 5%, 2.5%, 1.25%, 0.6%, 0.3% and 0.15% essential oil, as a positive control Penicillin clemizol of 1,000,000 U.I. and DMSO negative control, using the statistical program Infostat the statistical significance of the results is established, even if there was a halation inhibition for S. aureus ATCC 25923 at concentrations 2.5% and 5% oil essential for S. mutans ATCC 25175 0.15% for S. pyogenes ATCC 19615 2.5% and 0.3% and for S. pneumoniae ATCC 49619 2.5% and 0.3% effectiveness is statistically lower compared to the positive control .

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SIC and DRS are related proteins present in only four of the more than 200 Streptococcus pyogenes emm-types. These proteins inhibit complement mediated lysis and/or the activity of certain antimicrobial peptides. A gene encoding a homologue of these proteins, herein called DrsG, has been identified in the related bacterium Streptococcus dysgalactiae subsp equisimilis (SDSE). Here we show that geographically dispersed isolates representing 14 of 50 emm-types examined possess variants of drsG. However not all isolates within the drsG-positive emm-types possess the gene. Sequence comparisons also reveal a high degree of conservation in different SDSE emm-types. To examine the biological activity of DrsG, recombinant versions of two major DrsG variants, DrsGS and DrsGL, were expressed and purified. Western blot analysis using antisera raised to these proteins demonstrated both variants to be expressed and secreted into culture supernatant. Unlike SIC, but similar to DRS, DrsG does not inhibit complement mediated lysis. However, like both SIC and DRS, DrsG is a ligand of the cathelcidin LL-37 and is inhibitory to its bactericidal activity in in vitro assays. The greatest similarity between DrsG and DRS/SIC is found in the signal sequence at the amino terminus and proline rich domains in the C-terminal half of the protein. Conservation of prolines in this latter region also suggests these residues are important in the biology of this family of proteins. This is the first report demonstrating the activity of an AMP inhibitory protein in SDSE. These results also suggest that inhibition of AMP activity is the primary function of this family of proteins. The acquisition of complement inhibitory activity of SIC may reflect its continuing evolution.

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Streptococcus pyogenes causes severe invasive infections: the post-streptococcal sequelae of acute rheumatic fever (RF) and rheumatic heart disease (RHD), acute glomerulonephritis, and uncomplicated pharyngitis and pyoderma. Efforts to produce a vaccine against S. pyogenes began several decades ago, and different models have been proposed. Here, we describe the methodology used in the development of a new vaccine model, consisting of both T and B protective epitopes constructed as synthetic peptides and recombinant proteins. Two adjuvants were tested in an experimental inbred mouse model: a classical Freund`s adjuvant and a new adjuvant (AFCo1) that induces mucosal immune responses and is obtained by calcium precipitation of a proteoliposome derived from the outer membrane of Neisseria meningitides B. The StreptInCor vaccine epitope co-administrated with AFCo1 adjuvant induced mucosal (IgA) and systemic (IgG) antibodies as preferential Th1-mediated immune responses. No autoimmune reactions were observed, suggesting that the vaccine epitope is safe. (c) 2009 Elsevier Inc. All rights reserved.

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Cepas de Streptococcus salivarius, isoladas de crianças com e sem dor de garganta, foram testadas quanto à produção de bacteriocina contra Streptococcus pyogenes. Os resultados mostraram que as crianças que não tinham dor de garganta possuiam, na boca, cepas de bactérias produtoras de substâncias inibidoras semelhantes à bacteriocina contra S. pyogenes.

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Samples of tongue and bucal mucosa surfaces were obtained from six healthy subjects with the purpose of isolating S. salivarius. It was verified that 47 out of 48 S. salivarius strains produced bacteriocin-like substances against at least one of the indicator species: Actinomyces viscosus, Rothia dentocariosa, Streptococcus pyogenes, Staphylococcus aureus, Streptococcus mutans and Streptococcus sanguis. The method employed to test for bacteriocin production was that of deferred antagonism. The results showed that there was a high antagonism against R. dentocariosa, S. pyogenes and A. viscosus; extremely low against S. mutans and S. sanguis and no inhibition for S. aureus.

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Pharyngotonsillitis by beta-hemolytic Streptococcus mostly affects children and imunocompromissed, being Streptococcus pyogenes (Group A) the most common agent in bacterial pharyngotonsillitis. Aim: This work targeted the research of beta-hemolytic Streptococcus Group-A (SBHGA) and No-A (SBHGNA) in the oropharynx of individuals with special health needs from the APAE (Maceio-AL). Method: A prospective study with oropharynx samples from patients with Down syndrome and other mental disorders (test) and students from a private school (control) aged 5-15 years. Cultures in blood agar (5%) were identified through Gram/catalase tests and bacitracin/trirnethoprim-sulfamethoxazole disk diffusion method, applying the chi-squared statistical analysis. Results: A total of 222 bacterial colonies were isolated in 74 individuals from APAE and 65 in the control group. In the test group, previous episodes of pharyngotonsillitis were reported by 36.49% (27/74) and 9.46% (7/74) were diagnosed with symptoms and/or signs suggestive of oropharynx infection. No positive sample of S. pyogenes was confirmed at APAE, being all samples classified as SBHGNA, with 5 SBHGA in the control group. Conclusion: The early identification of beta-hemolytic Streptococcus is important for the fast treatment of pharyngotonsillitis and the absence of S. pyogenes avoid future suppurative or not-suppurative sequels in the group from APAE.

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To circumvent the need to engineer pathogenic microorganisms as live vaccine-delivery vehicles, a system was developed which allowed for the stable expression of a wide range of protein antigens on the surface of Gram-positive commensal bacteria. The human oral commensal Streptococcus gordonii was engineered to surface express a 204-amino acid allergen from hornet venom (Ag5.2) as a fusion with the anchor region of the M6 protein of Streptococcus pyogenes. The immunogenicity of the M6-Ag5.2 fusion protein was assessed in mice inoculated orally and intranasally with a single dose of recombinant bacteria, resulting in the colonization of the oral/pharyngeal mucosa for 10-11 weeks. A significant increase of Ag5.2-specific IgA with relation to the total IgA was detected in saliva and lung lavages when compared with mice colonized with wild-type S. gordonii. A systemic IgG response to Ag5.2 was also induced after oral colonization. Thus, recombinant Gram-positive commensal bacteria may be a safe and effective way of inducing a local and systemic immune response.

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The pathogenic Gram-positive bacterium Streptococcus pyogenes (group A streptococcus) is the causative agent of numerous suppurative diseases of human skin. The M protein of S. pyogenes mediates the adherence of the bacterium to keratinocytes, the most numerous cell type in the epidermis. In this study, we have constructed and analyzed a series of mutant M proteins and have shown that the C repeat domain of the M molecule is responsible for cell recognition. The binding of factor H, a serum regulator of complement activation, to the C repeat region of M protein blocked bacterial adherence. Factor H is a member of a large family of complement regulatory proteins that share a homologous structural motif termed the short consensus repeat. Membrane cofactor protein (MCP), or CD46, is a short consensus repeat-containing protein found on the surface of keratinocytes, and purified MCP could competitively inhibit the adherence of S. pyogenes to these cells. Furthermore, the M protein was found to bind directly to MCP, whereas mutant M proteins that lacked the C repeat domain did not bind MCP, suggesting that recognition of MCP plays an important role in the ability of the streptococcus to adhere to keratinocytes.

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The Group A Streptococcus (GAS), or Streptococcus pyogenes, is a strict human pathogen that colonizes a variety of sites within the host. Infections can vary from minor and easily treatable, to life-threatening, invasive forms of disease. In order to adapt to niches, GAS utilizes environmental cues, such as carbohydrates, to coordinate the expression of virulence factors. Research efforts to date have focused on identifying how either components of the phosphoenolpyruvate-phosphotransferase system (PTS) or global transcriptional networks affect the regulation of virulence factors, but not the synergistic relationship between the two. The present study investigates the role of a putative PTS-fructose operon encoded by fruRBA and its role in virulence in the M1T1 strain 5448. Growth in fructose resulted in induction of fruRBA. RT-PCR showed that fruRBA formed an operon, which was repressed by FruR in the absence of fructose. Growth and carbon utilization profiles revealed that although the entire fruRBA operon was required for growth in fructose, FruA was the main fructose transporter. The ability of both ΔfruR and ΔfruB mutants to survive in whole human blood or neutrophils was impaired. However, the phenotypes were not reproduced in murine whole blood or in a mouse intraperitoneal infection, indicating a human-specific mechanism. While it is known that the PTS can affect activity of the Mga virulence regulator, further characterization of the mechanism by which sugars and its protein domains affect activity have not been studied. Transcriptional studies revealed that the core Mga regulon is activated more in a glucose-rich than a glucose-poor environment. This activation correlates with the differential phosphorylation of Mga at its PTS regulatory domains (PRDs). Using a 5448 mga mutant, transcriptome studies in THY or C media established that the Mga regulon reflects the media used. Interestingly, Mga regulates phage-encoded DNases in a low glucose environment. We also show that Mga activity is dependent on C-terminal amino acid interactions that aid in the formation of homodimers. Overall, the studies presented sought to define how external environmental cues, specifically carbohydrates, control complex regulatory networks used by GAS, contribute to pathogenesis, and aid in adaptation to various nutrient conditions encountered.