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1
Smith, Jennifer Marie. "Characterization of host-bacteria interactions contributing to group B streptococcus colonization." Huntington, WV : [Marshall University Libraries], 2002. http://www.marshall.edu/etd/descript.asp?ref=64.
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Alshammari, Abdulaziz. "IN VITRO EFFECT OF STATINS ON STREPTOCOCCUS MUTANS, STREPTOCOCCUS SANGUIS, AND STREPTOCOCCUS SALVARIUS." Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/368075.
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Oral BiologyM.S.
Objectives: Cardiovascular disease (CVD), including heart attack, angina, and stroke, is ranked as the number one cause of mortality world wide. High blood cholesterol is linked to CVD and is an important risk factor. Statins – cholesterol lowering drugs- are first choice drugs for reducing the chance of suffering a CVD event. In the USA alone, approximately 32 million individuals take statins. Although randomized control trials of statins have demonstrated their efficacy in preventing CVD, much less information has been reported on their unintended effects. Although not thought of traditionally as antimicrobials, statins have been shown to have antimicrobial effects in vitro. The statins belong to a family of drugs that lower cholesterol levels by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase, a rate limiting enzyme in the human mevalonate pathway of which cholesterol in the biosynthetic end product. The mevalonate pathway is an important cellular metabolic pathway present in many bacteria. Hence, the aim of this study was to assess the in vitro efficacy of statins against selected strains of oral streptococci, as determined by the minimum inhibitory concentration. A second related objective is to assess the in vitro effect of statins on single species biofilm formation , as determined by binding of the same streptococci to hydroxyapatite pegs. Methods: The effect of statins on S. mutans, S. sanguis, and S. salivarius was determined by finding the minimum inhibitory concentration (MIC) by broth dilution assays. Simvastatin, pravastatin atorvastatin, and rousuvastatin were used in this study. The minimum inhibitory concentration was considered to be the lowest concentration of statin that prevented bacterial growth, i.e. a clear test tube. Experiments were repeated twice for each bacterial species. The effect of simvastatin, atorvastatin, and pravastatin on the ability of S. mutans and S. sanguis to form single species biofilm was assayed using sterile microplates and the MBEC Biofilm Inoculator (Innovatech). Results: Two trials indicated that the MIC of simvastatin against the selected oral bacteria was determined to be 15.6 μg/ml for S. mutans and S. sanguis, and 7.8 μg/ml for S. salivarius. The MIC of rosuvastatin and atorvastatin was determined to be 100 μg/ml against all three streptococci, whereas the MIC of pravastatin was even higher (200 μg/ml) against all three streptococci. Likewise, two trials indicated that statins decreased single species biofilm formation by S. mutans and S. sanguis. For simvastatin, biofilm formation was decreased by concentrations eight fold below the MIC . The results were substantiated by spectrophotometric assay . For atorvastatin and pravastatin, biofilm formation was decreased by concentrations 3-4 fold below the MIC. Conclusions: These experiments demonstrate the in vitro antimicrobial effect of statins on S. mutans, S.sanguis, and S. salivarius. The data indicate that the statins inhibit growth of the test organisms with MIC’s ranging from 7.8-200 μg/ml. Simvastatin has in vitro efficacy against the specific strains of bacteria used in this study at concentrations slightly less than the observed MIC’s of 15.6-7.8 μg/ml . The MIC’s for atorvastatin, pravastatin, and rosuvastatin are much higher than simvastatin, in the range of 100-200 μg/ml . The effects of statins on biofilm parallels the effect on growth of the bacteria.
Temple University--Theses
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Flock, Margareta. "Development of a vaccine against strangles /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-500-3/.
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Steward, Karen Frances. "Comparative genomics of Streptococcus equi and Streptococcus zooepidemicus." Thesis, University of Cambridge, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708551.
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Hale, John D. F., and n/a. "Small bacteriocins produced by Streptococcus mutans and Streptococcus sanguis." University of Otago. Department of Microbiology & Immunology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20060905.144149.
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Dental caries is the most common bacterial disease of humans and occurs when oral bacteria produce acids, following their fermentation of dietary carbohydrates. This acid can then cause a localised demineralisation of the tooth surface. A group of seven species of bacteria, collectively known as the mutans streptococci, have been predominantly implicated in the onset of dental caries. In particular, Streptococcus mutans and Streptococcus sobrinus have been shown to be the main aetiological agents of this disease in humans. Most attempts to control the microbial component of caries target these bacteria.
The past 50 years has provided considerable information about the pathogenesis of dental caries, the likely route and time of transmission of cariogenic bacteria to susceptible hosts and possible ways of either treating or controlling the onset of this disease. In regards to the latter, many techniques (such as the use of tooth brushes, mouth washes, dental floss and tooth paste) for the control of plaque build-up exist and the examples listed are generally part of a daily routine. However, these techniques need to be applied regularly, and as such only highly-motivated individuals generally experience improved oral health. Therefore, the search for more effective less labour-intensive approaches continues. One area of research is into the potential application of small ribosomally-synthesised antimicrobial peptides, known as bacteriocins. Bacteriocins generally inhibit closely-related species that occupy the same ecological niche. Their relatively-specific targeting, plus the fact that many are remarkably heat and chemically-stable molecules, makes them excellent candidates for possible anti-caries applications.
Numerous bacteriocins produced by the lactic acid bacteria have now been identified. Most can be broadly categorised into one of four main classes, of which Class I, the lantibiotics and Class II, the small (<10 kDa) non-modified peptides, contain the most examples. Many screens for anti-mutans streptococcal (MS) bacteriocins have been carried out and it appears that the best source of anti-MS bacteriocins are the mutans streptococci themselves. Research in this laboratory has identified examples of anti-mutans streptococcal bacteriocins produced by both mutans streptococci and non-mutans streptococci. The present study investigated the anti-MS inhibitors produced by two streptococcal strains, S. mutans N and Streptococcus sanguis K11. During the course of this study a third strain, S. mutans UA159, was also studied for its bacteriocinogenic properties.
Although S. sanguis K11 produces anti-mutans streptococcal inhibitory activity, this appears only effective against Streptococcus rattus. In addition however, the inhibitory activity of this strain is also directed against all tested strains of Streptococcus agalactiae and ca. 50% of Streptococcus pyogenes. In the present study a 5069 Da novel inhibitory agent (sanguicin K11) was characterised and shown responsible for this unusual inhibitory spectrum. Through reverse genetics the sanK11 locus was identified and shown to encode a Class II type bacteriocin, the first shown to be produced by S. sanguis. Following screens of additional S. sanguis, sanK11 was shown to be present only in strains producing the same type of inhibitory pattern (P-type) as strain K11. The cysteine residues at positions 7 and 38 of the sanguicin K11 propeptide were shown to form a disulphide bridge essential for sanguicin K11 inhibitory activity.
S. mutans N and eight other S. mutans strains have been found to have what appears to be the same inhibitory spectrum, which includes members of the mutans streptococci and several other oral streptococcal species. One strain (UA140) of the eight has previously been shown to produce the lantibiotic mutacin I and the non-lantibiotic mutacin IV. S. mutans N was known to produce the non-lantibiotic mutacin N. The current study set out to investigate how two strains, apparently producing completely different bacteriocins could have the same inhibitory spectrum. Reverse genetics identified the mutacin N structural gene (mutN) and mutagenesis studies showed that this bacteriocin was responsible only for the inhibitory activity against mutans streptococci. Further sequencing around the mutN locus identified a second bacteriocin-like locus (mutO) adjacent to mutN. mutO was also identified to have anti-mutans streptococcal inhibitory activity and because of the close proximity of mutO and mutN and given the homology they share with other known two-peptide bacteriocins it seemed probable that mutacins O and N are components of a new member of this special class of bacteriocins (Class IIb, the two peptide bacteriocins) in which the optimal inhibitory activity is dependent on the co-operative activity of the two peptides.
Further investigations of strain N examined the expression of mutacins O and N. During a search for a suitable heterologous non-mutacinogenic S. mutans strain to act as an expression host, the genome reference strain, S. mutans UA159 was given consideration. However, contrary to previous reports, this strain was found to exhibit bacteriocin-like inhibitory activity. During a follow-up investigation, strain UA159 was found to inhibit 84 strains representing 11 different species of bacteria, but no inhibition of mutans streptococci was detected. The locus (nlmAB) encoding the two-peptide bacteriocin mutacin IV was identified within the UA159 genome. Using genetic dissection of nlmA and nlmB, the contribution of each peptide was examined and it was found that only the NlmA* propeptide appears to be active, raising doubts as to whether mutacin IV is a bona fide two-peptide bacteriocin. Deletion of the entire nlmAB locus created a mutant strain that exhibited a loss of inhibitory activity against the same 64 strains as was found for the nlmA mutant. A BLASTP search for the consensus leader sequence that precedes the propeptide of Class II bacteriocins, identified ORFs encoding 9 more putative bacteriocin-like peptides. Further genetic dissection identified the SMU.1914c locus as being responsible for the inhibitory activity against a further 15 strains not already sensitive to mutacin IV. SMU.1914c was renamed mutacin V. However, it appears that another as yet unidentified mutacin(s) is also produced by strain UA159 given that three indicator strains still remained sensitive to a double mutant [UA[Delta](1914/NlmAB)] in which both the mutacin IV and putative mutacin V loci were inactivated.
Export of Class II bacteriocins has been found to occur by either a SEC-dependent system or via a dedicated peptide ATP Binding Cassette (ABC) transporter. Three potential ABC transporter ORFs were identified in S. mutans UA159. Two (comA and cslA) had the characteristic accessory factor ORF (comB and cslB respectively) located adjacent to the main ABC transporter ORF, while the third ORF763 appeared to lack this. Mutagenesis of each of these five ORFS was carried out and confirmed cslAB to be the ABC transporter involved in the export of the competence stimulating factor, while the function of ORF763 could not be established in this study. Mutagenesis of either comA or comB resulted in a complete cessation of bacteriocin production by the respective mutant strains. Historically, comA and comB is the nomenclature used for loci encoding the exporter of the competence inducing factors in streptococci. In light of this new information, comA and comB were renamed nlmT and nlmE respectively, to account for the newly defined role of this ABC transporter.
The present study investigated four bacteriocins two of which (sanguicin K11 and mutacin ON) appear to have some potential for application to anti-caries control, and the others (mutacins IV and V) being shown to be produced by the genome reference strain (UA159). All three mutacins were shown to be exported from their respective producer cells by the NlmTE ABC transporter, while sanguicin K11 is predicted to be exported by a peptide ABC transporter located adjacent to sanK11.
Bacteriocins may yet provide a novel alternative for the treatment and control of dental caries. In their favour is that fact that they have relatively narrow defined inhibitory spectra and thus are unlikely to produce widespread changes to plaque ecosystems. Potential uses include as topical agents where bacteriocin preparations could be incorporated into dentrifices such as toothpastes or mouthwashes. Alternatively, streptococci producing anti-mutans streptococcal bacteriocins could be implanted into the oral cavity in strain replacement therapy strategies. There are pros and cons to each technique and the most effective anti-caries control appears more likely to result from "cocktail therapy" where bacteriocins are combined with a number of other anti-mutans streptococcal agents to achieve long-lasting protection against mutans streptococcus proliferation.
6
Garcia, Febres Julio Carib. "A comparative investigation of Streptococcus agalactiae isolates from fish and cattle." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Dissertations/GARCIA_JULIO_46.pdf.
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Cazajous, Marie. "Infections humaines à streptococcus suis type II : à propos d'un cas." Bordeaux 2, 1992. http://www.theses.fr/1992BOR2M148.
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De, Negri Rafaela. "EQUINE SERUM ANTIBODY RESPONSES TO STREPTOCOCCUS EQUI AND STREPTOCOCCUS ZOOEPIDEMICUS." UKnowledge, 2013. http://uknowledge.uky.edu/gluck_etds/13.
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Streptococcus zooepidemicus (Sz) and Streptococcus equi (Se) share 98% DNA sequence homology, but display different pathogenic properties. Infection by one organism does not cross-protect against the other. To better understand pathogenic differences between these organisms and gain information about which proteins are expressed in horses infected experimentally with Se, intrauterine Sz or naturally with respiratory Sz we compared antibody specificities of convalescent sera using ELISA. These comparisons were based on sets of 8 and 14 immunoreactive recombinant proteins of Se strain CF32 and Sz strain NC78, respectively. Sera from donkeys that were previously naturally affected with strangles and later developed Sz pneumonia secondary to an experimental influenza challenge were also included.
Serum antibody responses were quantitatively and qualitatively much greater following recovery from strangles than following respiratory Sz infection. Increased reactions to Se proteins IdeE2, Se75.3, Se46.8, Se18.9 and Se42.0 were observed for the majority of strangles sera but not for sera from respiratory Sz infection cases. Reactions of sera from Sz respiratory disease to Sz proteins varied greatly and were mostly to HylC and ScpC. Interestingly, sera of donkey recovered from Sz bronchopneumonia did not show increased antibody reaction to any of the proteins even though these donkeys had also recovered from clinical strangles 6 months previously. Only 1/5 mare with Sz placentitis presented increased serum antibody responses to MAP. In conclusion, adaptive immune responses to Se of horses with strangles are stronger and involve a greater number of proteins than adaptive immune responses to Sz infection of the lower respiratory tract.
In an effort to develop an improved vaccine against Se, modified live strain of EHV-1, RacH was constructed to express three recombinant antigens of Se SeM, IdeE and Se18.9. Two groups of 10 and 2 ponies were vaccinated intramuscularly or intranasally, respectively. Another group (n=6) vaccinated with empty RacH served as controls. Sera from 2/3 ponies from each vaccination groups and 1/2 serum from IN vaccinated ponies showed increased serum neutralizing antibodies to EHV-1. ELISA detected no significant increase in antibodies to proteins. Only one IM and IN vaccinated pony showed serum bactericidal activity post vaccination.
9
Vaillancourt, Katy. "Étude comparative des opérons galactose de Streptococcus salivarius et Streptococcus thermophilus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ56776.pdf.
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De, Winter Leanne Marie. "Characteristics of Streptococcus canis from canine streptococcal toxic shock syndrome and necrotizing fasciitis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ33219.pdf.
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Baudet, Géraldine. "Détermination des sérotypes et des profils estérasiques de souches de streptocoques du groupe B isolées chez le nouveau-né et relation avec la virulence." Paris 5, 1995. http://www.theses.fr/1995PA05P193.
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Kong, Fanrong. "Integrated study of group B streptococcus and human ureaplasmas : the paradigm shifts." Thesis, The University of Sydney, 2004. http://hdl.handle.net/2123/592.
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Group B streptococcus (GBS, S. agalactiae) and human ureaplasmas (U. parvumand U. urealyticum) are two clinically and phylogenetically related, potential perinatal pathogens. Their relationships between genotypes and pathogenesis of GBS and ureaplasma infection were still not well understood, one of the reason is that both of them are still short of a very practical genotyping system. In the study, to solve the above problem we developed genotyping systems for the organisms (the second section). For human ureaplasmas, based on four genes/gene clusters (rRNAgene clusters, the elongation factor Tu genes, urease gene complexes and multiplebanded antigen genes), we designed many primer pairs suitable for developing species identification assays for the two newly established human ureaplasma species (U. parvum and U. urealyticum). Further, based on the heterogeneity of ureaplasma multiple banded antigen gene (which contains species- and serovar-specific regions), we developed genotyping methods for each ureaplasma species.For GBS, based on three sets of molecular markers (capsular polysaccharidesynthesis gene clusters, surface protein antigen genes and mobile genetic elements),we developed a genotyping system. The primary evaluation of the genotyping systems showed that the genotyping systems were practical alternative assays for the conventional serotyping and they will be useful to further explore the relationships between genotypes and pathogenesis of GBS and ureaplasma infection. In the study, we introduced novel data and tools into GBS and ureaplasma studies especially from genomic- and bioinformatics-based molecular microbiology(the third section). For two newly established human ureaplasma species, based on the U. parvum serovar-3 genome, and using the above four important genes/geneclusters, we exposed some interesting problems in the understanding of newureaplasma taxonomy especially in the post genomic era. For GBS, we studied the two published full genomes and exposed some new problems or possible future new research fields. In particular we found the two finished and one ongoing GBS genomes were all non-typical and suggest that future genomic project had better have genetic population structure viewpoint. Finally, we suggested that integrated studies of the two potential or conditional perinatal pathogens, from the viewpoint of evolution, would provide a new understanding angle of the pathogenesis of the two organisms. Studies suggested that during coevolution, human ureaplasmas(especially U. parvum) became friendlier than their ancestors to their human host (by losing most of its virulence genes); however, GBS tried to increase its invasive abilities (by getting more virulence genes) to fight against the human host attack.
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Kong, Fanrong. "Integrated study of group B streptococcus and human ureaplasmas � the paradigm shifts." University of Sydney. Medicine, 2004. http://hdl.handle.net/2123/592.
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Group B streptococcus (GBS, S. agalactiae) and human ureaplasmas (U. parvumand U. urealyticum) are two clinically and phylogenetically related, potential perinatal pathogens. Their relationships between genotypes and pathogenesis of GBS and ureaplasma infection were still not well understood, one of the reason is that both of them are still short of a very practical genotyping system. In the study, to solve the above problem we developed genotyping systems for the organisms (the second section). For human ureaplasmas, based on four genes/gene clusters (rRNAgene clusters, the elongation factor Tu genes, urease gene complexes and multiplebanded antigen genes), we designed many primer pairs suitable for developing species identification assays for the two newly established human ureaplasma species (U. parvum and U. urealyticum). Further, based on the heterogeneity of ureaplasma multiple banded antigen gene (which contains species- and serovar-specific regions), we developed genotyping methods for each ureaplasma species.For GBS, based on three sets of molecular markers (capsular polysaccharidesynthesis gene clusters, surface protein antigen genes and mobile genetic elements),we developed a genotyping system. The primary evaluation of the genotyping systems showed that the genotyping systems were practical alternative assays for the conventional serotyping and they will be useful to further explore the relationships between genotypes and pathogenesis of GBS and ureaplasma infection. In the study, we introduced novel data and tools into GBS and ureaplasma studies especially from genomic- and bioinformatics-based molecular microbiology(the third section). For two newly established human ureaplasma species, based on the U. parvum serovar-3 genome, and using the above four important genes/geneclusters, we exposed some interesting problems in the understanding of newureaplasma taxonomy especially in the post genomic era. For GBS, we studied the two published full genomes and exposed some new problems or possible future new research fields. In particular we found the two finished and one ongoing GBS genomes were all non-typical and suggest that future genomic project had better have genetic population structure viewpoint. Finally, we suggested that integrated studies of the two potential or conditional perinatal pathogens, from the viewpoint of evolution, would provide a new understanding angle of the pathogenesis of the two organisms. Studies suggested that during coevolution, human ureaplasmas(especially U. parvum) became friendlier than their ancestors to their human host (by losing most of its virulence genes); however, GBS tried to increase its invasive abilities (by getting more virulence genes) to fight against the human host attack.
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Bracht, Dagmar. "Proteomanalyse von Streptococcus pneumoniae." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=977729931.
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Petersen, Helen J. "Streptococcus-induced thrombus formation." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.541609.
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Kurenbach, Brigitta. "Konjugativer DNA-Transfer zwischen Gram-positiven und Gram-negativen Spezies: Transferkomponenten des Multiresistenzplasmids pIP501 aus Streptococcus agalactiae." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971485305.
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Vasi, József. "Characterization of two potential virulence factors in Streptococcus dysgalactiae /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5758-0.pdf.
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Berge, Andreas. "Molecular analysis of Streptococcus pyogenes and its interactions with the human host." Lund : Lund University, 1997. http://catalog.hathitrust.org/api/volumes/oclc/68945123.html.
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Darenberg, Jessica. "Streptococcus pyogenes infections and toxic shock syndrome : molecular epidemiology and immunotherapy /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-676-X/.
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Medina, Flores Dyanne Adenea, Urizar Gabriela Ulloa, Colarossi Rosella Camere, García Stefany Caballero, Tovalino Frank Mayta, and Valle Mendoza Juana Del. "Antibacterial activity of Bixa orellana L. (achiote) against Streptococcus mutans and Streptococcus sanguinis." Universidad Peruana de Ciencias Aplicadas (UPC), 2016. http://hdl.handle.net/10757/604437.
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Objective To evaluate the cytotoxic and antibacterial effect of Bixa orellana L. (B. orellana) (achiote) methanol extract against Streptococcus mutans (ATCC 25175) (S. mutans) and Streptococcus sanguinis (ATCC 10556) (S. sanguinis). Methods Two methanol extracts of B. orellana were prepared in vitro, from the seeds and leaves. The antibacterial activity of extracts against S. mutans and S. sanguinis was evaluated using the cup-plate agar diffusion method. The minimum inhibitory concentration (MIC) was determined using the microdilution method and the cytotoxic activity was determinated by using the cell line MDCK. Results A stronger antibacterial effect was observed with the leaves methanolic extract with an inhibition zone of (19.97 ± 1.31) mm against S. mutans and (19.97 ± 1.26) mm against S. sanguinis. The methanolic extract of the seeds had an activity of (15.11 ± 1.03) mm and (16.15 ± 2.15) mm against S. mutans and S. sanguinis, respectively. The MIC of the leaf and the seed extracts against S. sanguinis was 62.5 and 125 μg/mL, respectively, and the MIC of the leaf extract against S. mutans was 62.5 μg/mL, and for the seed extract it was 31.25 μg/mL. The 50% cytotoxic concentration was 366.45 and 325.05 μg/mL for the leaves and seeds extracts, respectively. Conclusions The experimental findings demonstrated the antibacterial effect of the methanolic extract of B. orellana (achiote) on S. mutans and S. sanguinis. The extract of this plant is cytotoxic at high concentrations.Peer review
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Camere, Colarossi Rosella, Urizar Gabriela Ulloa, Flores Dyanne Medina, García Stefany Caballero, Tovalino Frank Mayta, and Valle Mendoza Juana Mercedes Del. "Antibacterial activity of Myrciaria dubia (Camu camu) against Streptococcus mutans and Streptococcus sanguinis." Elsevier B.V, 2016. http://hdl.handle.net/10757/620656.
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Objective: To evaluate the antibacterial and cytotoxic effect of Myrciaria dubia (Camu camu) (M. dubia) methanol extract, against Streptococcus mutans (ATCC 25175) (S. mutans) and Streptococcus sanguinis (ATCC 10556) (S. sanguinis). Methods: Two methanol extracts of M. dubia were prepared in vitro, from the seeds and pulp. Ten independent tests were prepared for each type of extract, using 0.12% chlorhexidine solution as positive control. Agar diffusion test was used by preparing wells with the experimental solutions cultivated in anaerobic conditions for 48 h at 37 °C. Meanwhile, the minimum inhibitory concentration and the cytotoxic effect over MDCK cell line was found. Results: A higher antibacterial effect was observed with the methanol seed extract with an inhibitory halo of (21.36 ± 6.35) mm and (19.21 ± 5.18) mm against S. mutans and S. sanguinis, respectively. The methanol extract of the pulp had an effect of (16.20 ± 2.08) mm and (19.34 ± 2.90) mm, respectively. The minimum inhibitory concentration of the pulp extract was 62.5 µg/mL for both strains, whereas for the seed antibacterial activity was observed even at low concentrations. The CC50 of the seeds extract was at a higher concentration than 800 µg/mL and 524.37 µg/mL for the pulp extract.This study was supported by Universidad Peruana de Ciencias Aplicadas (UPC) Lima-Peru with Grant No. MANUSCRIPT ACCEPTED ACCEPTED MANUSCRIPT UPC-501-2015
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Wennekamp, Julia [Verfasser], and Philipp [Akademischer Betreuer] Henneke. "Modulation of phagocyte apoptosis by Streptococcus agalactiae = Modulation von Phagozytenapoptose durch Streptococcus agalactiae." Freiburg : Universität, 2011. http://d-nb.info/1123462895/34.
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Luis, Philippe Renard Vincent. "Le TDR modifie-t-il la pratique des médecins généralistes d'Ile de France ?" Créteil : Université de Paris-Val-de-Marne, 2006. http://doxa.scd.univ-paris12.fr:80/theses/th0240166.pdf.
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Malerba, Mariangela. "The immunomodulatory role of epidermal hepcidin in infectious condition." Thesis, Sorbonne Paris Cité, 2018. https://wo.app.u-paris.fr/cgi-bin/WebObjects/TheseWeb.woa/wa/show?t=2166&f=13318.
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L'hepcidine, initialement identifiée comme un peptide antimicrobien, s'est révélée être un peptide hormonal clé du métabolisme du fer capable d'inhiber l'absorption intestinale du fer alimentaire et son recyclage par les macrophages. L'expression de l'hepcidine est induite par l’excès de fer mais également en réponse à l' infection/inflammation. L'hepcidine, comme son nom l'indique, est principalement synthétisée par les hépatocytes mais également, à plus faibles niveaux, par d'autres types cellulaires. Notre équipe a démontré que ce peptide hépatique était suffisant pour assurer l'homéostasie systémique du fer en conditions physiologiques suggérant un rôle local de l'hepcidine extra-hépatique en conditions physiopathologiques. L'hepcidine présente une similarité de structure avec les beta-défensines, une sous-famille de peptides antimicrobiens (AMPs). Les AMPs sont de petites protéines ayant des fonctions antimicrobiennes mais aussi immuno-régulatrices. De manière intéressante, nous avons observé une forte similarité de structure entre l'hepcidine humaine et l' IL-8, chimiokine des neutrophiles et démontré que l'hepcidine induit la migration des neutrophiles in vitro. Nous avons confirmé par bioluminescence que l'hepcidine est également capable de recruter des neutrophiles in vivo. Ainsi, de manière surprenante, nous avons décrit une nouvelle fonction immuno-modulatrice de cet AMP. Les épithelia, comme l' intestin et la peau, sont la principale source des AMPs. Or, l'expression de l'hepcidine et son rôle en tant qu'AMP dans ces tissus n'a jamais été investigué. J'ai, au cours de ma thèse spécifiquement étudié le rôle de l'hepcidine dans la peau lors d'une infection sous-cutanée (SC) aux streptocoques de groupe A (GAS). Ces bactéries peuvent coloniser la peau et sont responsables d'une large gamme d'infections cutanées superficielles et invasives. Les AMPs produits par les cellules épithéliales et par les cellules immunitaires circulantes (neutrophiles et macrophages) sont les premières « lignes de défense » contre les GAS. Les infections SC par GAS représentent donc un très bon modèle pour étudier la fonction de l'hepcidine comme peptide antimicrobien dans la peau. Nous avons généré des souris des KO conditionnelles de l'hepcidine dans les kératinocytes (Hepc KOker) et dans les cellules myéloïdes (Hepc KOmyel) et soumis ces souris à des modèles d'infection SC par GAS. Nous avons observé que les souris Hepc KOmyel et WT présentent le même nombre de bactéries au niveau local et au niveau systémique, alors que les souris Hepc KOker sont beaucoup plus sensibles à l'infection que les WT, avec un nombre significativement plus élevé de bactéries au niveau de la lésion et une plus grande dissémination systémique. Nous avons observé que l'hepcidine n'avait ni effet bactériostatique ni bactériolytique contre les GAS in vitro et que les kératinocytes primaires WT et Hepc KOker présentaient la même activité bactéricide. De façon intéressante, nous avons constaté que l'hepcidine stimule la sécrétion de CXCL1, chimiokine des neutrophiles, par les kératinocytes primaires. En accord avec ces résultats, l' expression de CXCL1 et le nombre de neutrophiles recrutés sur le site de l' infection sont plus faibles chez les souris Hepc KOker que chez les WT. De plus, l' injection SC de CXCL1 corrige ces défauts, confirmant que le défaut de production de CXCL1 est responsable de l'infection observée chez les souris Hepc KOker. Enfin, nous démontrons que l' injection d'hepcidine exogène empêche la propagation de l'infection. En conclusion notre travail met en évidence un nouveau rôle protecteur de l'hépcidine épidermique contre l'infection à GAS, à travers la modulation du recrutement des neutrophiles et suggèrent que l'hepcidine pourrait représenter une nouvelle approche pour le traitement des infections à GASHepcidin, first discovered as an antimicrobial peptide, is now considered as the key iron regulatory hormone, inhibiting duodenal iron absorption and iron recycling by macrophages. Hepcidin expression is induced by iron accumulation and infection/inflammation while diminished in situations of iron needs. Hepcidin, as suggested by its name, is mainly expressed in the liver (Hep- for Hepatic) but also at low levels by many other cells. Our team has demonstrated that hepatic hepcidin is sufficient to ensure the systemic iron homeostasis in basal conditions; suggesting that extra-hepatic hepcidin could play local roles in pathophysiological conditions. Hepcidin contains 4 disulfide bonds with β-sheet fold and positively charged residues at the surface, showing close structural similarity to beta-defensins, a subfamily of antimicrobial peptides (AMP). AMPs are small proteins with antimicrobial activities but also immunomodulatory functions (chemotaxis, ...). Because hepcidin possesses disulfide bridges, resembling the intramolecular disulfide bonds critical for the function of chemokine proteins, we investigated the direct chemoattractant potential of hepcidin. We observed that human hepcidin shares structural similarities with the human CXCL1 homologue and demonstrated that hepcidin triggers neutrophil migration in vitro with a bell-shaped dose response curve, characteristic of chemokines. Taking advantage of in vivo bioluminescence assay, we confirmed that SC injection of hepcidin causes neutrophil recruitment in vivo. These results highlight a new immunomodulatory role of this AMP. Epithelia, such as intestine and skin, are the main source of AMPs. However, expression of hepcidin and its functional role as AMP in these tissues has never been studied. Therefore, I specifically investigated this aspect in the skin, using a model of group A streptococcal (GAS) subcutaneous (SC) infection. These gram-positive bacteria commonly colonize skin and are responsible for a wide range of both skin and invasive infections causing more than 500,000 deaths per year. The first host immune effectors encountered by GAS are endogenous AMP produced by epithelial cells and by circulating immune cells (neutrophils and macrophages) so GAS represents a tremendous model to study hepcidin function as antimicrobial peptide in the skin. We specifically deleted hepcidin in keratinocytes (Hepc KOker) and in myeloid cells (Hepc KOmyel). Interestingly, while Hepc KOmyel and WT littermates showed the same number of bacteria at local and systemic level, we found that Hepc KOker mice present a worse outcome after infection than WT littermates, with a significantly higher number of bacteria at the lesion site and a stronger systemic spread of infection. We observed that hepcidin has neither bacteriostatic nor bacteriolytic effect against GAS in vitro and that both WT and Hepc KOker primary keratinocytes displayed the same bactericidal activity. Interestingly, we found that hepcidin promotes keratinocyte secretion of CXCL1, a key neutrophil chemokine, in vitro. Consistently, both the amount of CXCL1 and the number of neutrophils recruited at the site of infection was lower in Hepc KOker mice compared to WT littermates. Moreover, CXCL1 SC injections rescue the phenotype, confirming that the invasiveness observed in Hepc KOker is specifically caused by the absence of hepcidin-mediated CXCL1 production. Finally, we demonstrated that injections of exogenous hepcidin prevents the infection spread. These results highlight a new protective role of epidermal hepcidin against GAS infection, through modulation of neutrophil recruitment and suggest that hepcidin could represent a novel approach for therapy of GAS infections
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Beck, Isabel L. "Tolérance à la pénicilline G de souches de "Streptococcus pyogenes" isolées au cours d'angines aigue͏̈s de l'enfant." Paris 5, 1993. http://www.theses.fr/1993PA05P199.
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Jacobs, Jan Adriaan. "Streptococcus milleri relevance of species /." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1996. http://arno.unimaas.nl/show.cgi?fid=6650.
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Koo, Kun, and 古軍. "Vancomycin tolerance in streptococcus pneumoniae." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31970588.
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Zhang, Meng. "Proteomic analysis of streptococcus pyogenes." Thesis, Northumbria University, 2007. http://nrl.northumbria.ac.uk/842/.
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Streptococcus pyogenes (group A streptococcus, GAS) is a major human Gram-positive pathogen that causes infections that normally occur in the respiratory tract, the skin, the wound, the lung, the bloodstream and/or muscle tissues and result in millions of deaths every year. To cause such infections, S. pyogenes produces a wide range of virulence factors. The destruction of connective tissue and the hyaluronic acid therein plays an important role in pathogenesis. S. pyogenes was propagated in hyaluronic acid rich growth media in an attempt to create a simple biological system that could reflect some elements of the pathogenesis. The growth of bacteria was analyzed in the hyaluronic acid rich media and control media and a proteomic approach was applied to identify those proteins that were differentially expressed by the streptococcal pathogens growing in the different media. The techniques of two dimensional gel electrophoresis and static nanospray mass spectrometry were optimized and proteome maps for S. pyogenes grown in both media were constructed. The differentially expressed proteins by S. pyogenes were identified and analyzed using bioinformatics. Our results showed that several recognized virulence factors of S. pyogenes were upregulated in hyaluronic acid rich media, including the Ml protein, a collagen-like surface protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, which has been shown to play important roles in streptococcal pathogenesis. Interestingly, two hypothetical proteins of unknown function were also up-regulated and detailed bioinformatics analysis showed that at least one of these hypothetical proteins is likely to be involved in GAS pathogenesis. It was therefore concluded that this simple biological system provided a valuable tool for the identification of potential streptococcal pathogens virulence factors.
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Lewis, Christopher Roger. "Chromosomal deletions in Streptococcus mutans." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297569.
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James, Peter Alan. "Penicillin tolerance in Streptococcus sanguis." Thesis, University of the West of England, Bristol, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303198.
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Wyres, Kelly L. "Genome evolution in Streptococcus pneumoniae." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:985b1fc6-c1a9-41b3-a20a-1735329d962b.
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Streptococcus pneumoniae (the pneumococcus) is a bacterial pathogen responsible for >1.6 million annual deaths globally. Pneumococcal penicillin-resistance is conferred by acquisition of ‘altered’ penicillin-binding protein (pbp) genes. The first penicillin-nonsusceptible pneumococci were identified in the late 1960s. Global pneumococcal penicillin-nonsusceptibility rates rapidly increased in the 1980s/90s. Since 2000, protein-conjugate vaccines, targeting 7, 10 or 13 of the ≥94 different pneumococcal capsule types (serotypes), have been introduced in many countries. Following vaccine implementation there has been a decline in vaccine-type pneumococcal disease and an increase in non-vaccine-type disease. These epidemiological changes result from “serotype replacement” and/or “serotype switching”. The former describes the expansion of non-vaccine-type clones in the absence of vaccine-type pneumococci. The latter describes serotype change following recombination at the capsule polysaccharide synthesis (cps) locus. To fully understand how pneumococci respond to vaccine- and antibiotic-induced selective pressures, we must better understand the evolutionary history of this pathogen. This thesis describes the study of a global collection of 426 pneumococci, dated 1937 - 2007. Serotype, genotype and penicillin-susceptibility data were collected. Nucleotide sequences of three pbp genes (for 389 isolates) and whole-genome sequences (for 96 isolates) were also generated. The data demonstrated the long-term persistence of certain clones within pneumococcal populations, and that pbp and large-fragment (>30 kb) cps ± pbp recombination was occurring prior to both widespread antibiotic use and vaccine implementation. The data highlighted the promiscuous nature of the globally-distributed PMEN1 clone and its contribution to the spread of pneumococcal penicillin-resistance. PMEN1 also donated multiple, large regions (1.7 - 32.3 kb) of its genome to at least two un-related clones. Finally, six “Tn916-like” genetic elements, conferring resistance to non-penicillin antibiotics, were newly identified. These included two of the oldest ever described. These results provided a unique insight into the history of pneumococcal evolution and the importance of genetic recombination.
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Rudmann, Emily. "Parsing the Streptococcus pneumoniae virulome." Thesis, Boston College, 2020. http://hdl.handle.net/2345/bc-ir:108795.
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Thesis advisor: Tim van OpijnenStreptococcus pneumoniae is a prominent gram-positive commensal and opportunistic pathogen which possesses a large pan-genome. Significant strain-to-strain variability in genomic content drives the use of varied pathways to perform similar processes between strains. Considering this variation, we employ a set of 36 strains, representative of 78% of total pan-genome diversity, with which to perform functional studies. We previously determined the set of genes required by 22 of the 36 strains to maintain successful infection in a host, or the virulome. In this work, we sought to parse from the virulome the genes required specifically for nasopharyngeal adhesion, a crucial step in S. pneumoniae colonization and transmission, and often a precursor to invasive disease, as well as gene requirements for subversion of the macrophage. We performed in vitro attachment Tn-seq in the 22 strains to D562 human nasopharyngeal epithelial cells, identifying thirteen factors that exhibit requirements for adhesion, and preliminarily validated a proposed universal requirement for survival of the macrophage by a killing assay using J774A.1 murine migratory macrophages
Thesis (BS) — Boston College, 2020
Submitted to: Boston College. College of Arts and Sciences
Discipline: A&S Honors
Discipline: Biology
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Dossou-Gbete, Lucien. "Les infections a streptococcus anginosus." Université Louis Pasteur (Strasbourg) (1971-2008), 1991. http://www.theses.fr/1991STR1M147.
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Koo, Kun. "Vancomycin tolerance in streptococcus pneumoniae." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25139216.
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Alghofaili, Fayez Abdullah. "Streptococcus pneumoniae-stress hormone interactions." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/41267.
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Streptococcus pneumoniae is one of the most important bacterial pathogens of humans causing a wide range of mild to life-threating diseases. It is also a commensal microorganism in the nasopharynx of up to 60% of people. Fundamental aspects of its ability for transition from colonisation to an infectious state as well as how bacterial-host interactions influence this process are largely unknown. In the field of microbial endocrinology, it has been well established in mainly Gram-negative bacteria that stress hormones such as norepinephrine epinephrine and dopamine play an essential role in determining the outcome of bacterial infections. This study successfully established the conditions to investigate S. pneumoniae-stress hormone interactions using modified serum-SAPI media. 13 mutants lacking two-component regulatory system and 4 two-component system fusion reporter strains were created, and examined for their role in S. pneumoniae-stress hormone interactions. This study demonstrated that S. pneumoniae is stress hormone responsive and has mechanisms to recognise and process host stress hormones by a transferrin-iron delivery mechanism, which evidence suggests might be mediated via the TCS09 system since hormone-induced growth and radiolabelled norepinephrine and Fe uptake were reduced in a ΔTCS09 mutant. In addition, the pneumococcal response to stress hormone exposure resulted in a change in cell-cell association from chains into diplococci and cell morphology by reducing cell size and the capsule. Furthermore, the pneumococcal exposure to norepinephrine also increased biofilm formation and significantly altered metabolism. The analysis of in vivo experiments indicated that a stress hormone encounter might trigger translocation from the nasopharynx into the lungs, which may enhance S. pneumoniae in its transition from commensal to pathogen. Therefore, the pneumococcal ability to respond to host stress signals may be key to its capacity to cause life-threatening pneumonia, septicaemia and meningitis.
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Thevenot, Tracy Lynn. "Aspects of sugar transport via the phosphoenolpyruvate sugar phosphotransferase system of streptococcus mutans /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23673.pdf.
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Monteiro-Oliveira, Marcela Pinto 1982. "Estudo da ação antimicrobiana da terapia fotodinamica sobre lesões de carie produzidas in vitro na dentina de dentes bovinos." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288089.
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Orientador: Marines Nobre dos Santos UchoaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Durante o processo conhecido como terapia fotodinâmica, a aplicação de fotossensibilizadores associados a uma fonte de luz de comprimento de onda complementar, gera produtos que podem danificar componentes essenciais das células, e causar a morte celular. Dentro desse contexto, a aplicação dessa terapia sobre microrganismos presentes em lesões de cárie é de grande valia, uma vez que poderá reduzir a quantidade de tecido dental a ser removido no tratamento da cárie, diminuir as chances de progressão da doença bem como os riscos de acometimento pulpar do elemento dentário. Assim, o objetivo deste estudo in vitro foi determinar parâmetros para o uso de um diodo emissor de luz (LED) associado ao corante azul de orto toluidina (TBO) na redução da contagem de Streptococcus mutans presentes em lesões de cárie dentinária. Para isto, 72 espécimes de dentina coronária de dentes bovinos foram imersos em cultura contendo Streptococcus mutans para produzir lesões de cárie. Tais espécimes foram divididos aleatoriamente em 6 grupos (n=12): Controle (exposição a NaCl a 0,9% por 5 min); TBO (exposição ao TBO a 0,01% por 5 min); LEDA (exposição ao LED por 4,2 min); LEDB (exposição ao LED por 6,5 min); PDTA (exposição ao corante associado ao LED por 4,2 min) e PDTB (exposição ao corante associado ao LED por 6,5 min). As densidades de energia utilizadas para os tempos de 4,2 e 6,5 min, foram de 166 e 249 J/cm2, respectivamente. Antes e após os tratamentos, amostras de tecido dentinário cariado foram coletadas e analisadas microbiologicamente, por meio da contagem das unidades formadoras de colônia (UFC) de S. mutans. A profundidade das lesões de cárie produzidas pelo modelo microbiológico utilizado foi determinada por meio da microscopia de luz polarizada. Foram utilizados os testes ANOVA/Tukey para comparar os valores de log redução dos grupos (a=5%). Observou-se redução significativa de S. mutans nos grupos em que aplicou-se TBO associado ao LED, com as duas densidades de energia utilizadas. Entretanto, nenhuma diferença significativa foi encontrada para os diferentes tempos de irradiação. Concluiu-se que os parâmetros utilizados no presente estudo, para o emprego do LED associado ao TBO, foram efetivos em reduzir a contagem de S. mutans presentes em lesões de cárie dentinária.
Abstract: Photodynamic therapy (PDT) is a technique that consists in the activation of certain photosensitizers by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. In this context, this therapy may become a suitable approach to disinfect the dentin tissue during the caries treatment, and reduce the tissue removal, minimizing the probability of caries progression and pulp involvement. This randomized in vitro study determined parameters for using a light-emitting diode (LED) with toluidine blue O (TBO) for reduction of Streptococcus mutans counts inside dentin caries. Seventy two bovine coronary dentin slabs were immersed in Streptococcus mutans culture for demineralization production. Dentin slabs were allocated to 6 groups (n=12) as follows: Control (treated with 0.9% NaCl solution for 5 min); TBO (treated with 0.1 mg/ml TBO for 5 min); LEDA (submitted to irradiation for 4.2 min); LEDB (submitted to irradiation for 6.5 min); PDTA (treated with TBO plus irradiation for 4.2 min) and PDTB (treated with TBO plus irradiation for 6.5 min). The energy densities used for 4.2 and 6.5 min correspond at 166 and 249 J/cm2, respectively. Before and after treatments, dentin samples were analyzed with regard to S. mutans counts. The caries lesion depth produced by the microbiological model was analyzed by polarized light microscopy. ANOVA/Tukey tests were utilized to compare log reductions among groups (a=5%). Bacterial reduction was observed when dentin was exposed to both TBO and LED at both irradiation times. However, no difference in S. mutans reduction was found between the two energy densities. Concluding, although the use of LED combined with TBO was effective in reducing the Streptococcus mutans counts in carious dentin, this effect may not have clinical significance.
Mestrado
Odontopediatria
Mestre em Odontologia
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Vizoto, Natália Leal 1982. "Avaliação da função biológica do sistema de dois componentes SptRS de Streptococcus mutans." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288675.
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Orientador: Renata de Oliveira Mattos-GranerTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Streptococcus mutans é uma espécie bacteriana comum da microbiota bucal de seres humanos envolvida na patogênese da cárie dentária e em endocardites infecciosas promovidas por bacteremias de origem bucal. Para ser transmitido e ocupar seus nichos ecológicos, S. mutans precisa persistir na saliva e se adaptar fisiologicamente a cada fase da colonização, um processo que provavelmente envolve diversas alterações do seu transcriptoma. Para isto, S. mutans utiliza sistemas reguladores de transcrição de dois componentes (SDC). O SDC SptRS foi identificado através de análises in silico do genoma da cepa S. mutans UA159, como ortólogo do sistema SptSR (Spt de Saliva persistence) de Streptococcus pyogenes. O objetivo deste trabalho foi investigar a participação do sistema SptRS de S. mutans em fenótipos importantes para a colonização bucal. Para isto, mutantes knockout dos genes sptR e sptS, SMU.927 e SMU.928 respectivamente, foram construídos a partir da cepa UA159 (UAsptR- e UAsptS-) e comparados com a cepa parental em análises de morfologia, crescimento planctônico sob diferentes condições nutricionais, persistência em saliva humana, formação de biofilme e autólise a 44oC. Além disto, genes do regulon de SptRS foram pesquisados através de ensaios da Imunoprecipitacão de Cromatina seguido de sequenciamento (ChIP-seq), RT-PCR quantitativo (RT-PCRq) e de Ensaios de Retardamento da Mobilidade Eletroforética (EMSA) com proteína recombinante SptRr de S. mutans. Os mutantes sptR e sptS mostraram crescimento planctônico lento em meios de cultura RPMI e em MQD comparados à cepa parental, além de atividade autolítica reduzida em 22,4 e 53,13%, respectivamente. Não foram observadas, entretanto, alterações significativas na morfogênese, formação de biofilmes in vitro, nem na persistência em saliva humana. Os dados de ChIP-seq e RT-qPCR indicaram que SptRS regula genes envolvidos na resposta de estringência (SMU.926), repressão catabólica (ccpA), metabolismo de múltiplos açúcares (SMU.78, SMU.137, SMU.542, SMU.1734), sistemas fosfoenolpiruvato-fosfotransferase (PTS) (SMU.2047, SMU.114, SMU.115) sistemas de transporte do tipo ABC (SMU.182, SMU.880, SMU.905, SMU.1035, SMU.1095, SMU.1178c, SMU.1939) e biogênese de parede celular (SMU.1091, SMU.2147, SMU.609, SMU.1434c, SMU.22). SptR funcionou como um regulador negativo em 86% (37/43) dos genes testados. Análises de RT-qPCR e EMSA indicaram ainda que SptR regula diretamente o regulador de transcrição CovR (SMU.1924), envolvido na repressão de genes de virulência e formação de biofilmes. Este estudo fornece evidências de que SptRS regula diversas funções de S. mutans importantes para a sobrevivência em condições nutricionalmente escassos, aparentemente coordenando o metabolismo com o crescimento bacteriano e com a expressão de genes de virulência
Abstract: Streptococcus mutans is a common bacterial species of the bucal microbiota of humans involved in the pathogenesis of dental caries and infectious endocarditis promoted by bacteremia of bucal origin. To be transmitted and occupy their ecological niches, S. mutans need to persist in saliva and adapt physiologically to each phase of colonization, a process that probably involves several changes in its transcriptome. To this end, S. mutans uses transcriptional regulatory systems called Two Component System (TCS). The TCS SptRS was identified in an in silico analysis of the genome of S. mutans strain UA159, as an orthologue of the SptRS system (Spt of Saliva persistence) of Streptococcus pyogenes. The aim of this study was to investigate the role of the TCS SptRS in functional traits important for S. mutans to colonize its bucal niches. Thus, knockout mutants of sptR and sptS (SMU.927 and SMU.928, respectively) were obtained in strain UA159 (UAsptR-, UAsptS-) and compared to parental strain regarding morphology, planktonic growth under different nutritional conditions and persistence in human saliva, biofilm formation and autolysis at 44oC. In addition, genes of SptRS regulon were analised by Chromatin Immunoprecipitation followed the sequencing (ChIP-seq), quantitative RT-PCR (RT- qPCR) and Electrophoretic Mobility Shift Assays (EMSA) with S. mutans SptR recombinant protein. Inactivation of sptR/S promotes slow planktonic growth in RPMI and CDM, culture media 22.4 to 53.13% reductions in autolysis respectively, but does not significantly affect morphogenesis. However, mutants do not show significant alterations in biofilm formation or in persistence in human saliva. ChIP-seq and RT-qPCR analyses showed that SptRS regulates genes for stringent response (SMU.926), metabolism of multiple sugars (SMU.78, SMU.137, SMU.542, SMU.1734), catabolite repression (SMU.1591, ccpA), phosphoenolpyruvate phosphotransferase systems (PTS), ABC transport systems (SMU.182, SMU.880, SMU.905, SMU.1035, SMU.1095, SMU.1178c, SMU.1939) and cell wall biogenesis (SMU.22, SMU.609, SMU.1091, SMU.1434c, SMU.2147) SptR worked as a negative regulator of 86% (37/43) of the tested genes. RT-qPCR and EMSA analyses further showed that SptR directly represses expression of the transcriptional regulator CovR (SMU.1924), which is a repressor of genes involved in biofilm formation and virulence. This study provides evidence that SptRS regulates several functions important for S. mutans survival under poor nutritional conditions, apparently coordinating metabolism with bacterial growth and expression of virulence genes
Doutorado
Microbiologia e Imunologia
Doutora em Biologia Buco-Dental
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Carreño, Henríquez Daniel. "Porcentaje de streptococcus mutans y streptococcus sobrinus en el margen de restauraciones de resina compuesta y amalgama." Tesis, Universidad de Chile, 2007. http://repositorio.uchile.cl/handle/2250/138777.
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Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaAutor no autoriza el acceso a texto completo de su documento
La caries secundaria es la principal razón para reemplazar restauraciones. No sólo se relaciona directamente con algún defecto marginal, también requiere de la formación de placa con potencial cariogénico. En la etiología de la caries dental la especie Streptococcus mutans se considera la más importante. Streptococcus sobrinus también se encuentra involucrado en este proceso. Amalgamas y resinas compuestas son los materiales más utilizados en la actualidad para restaurar dientes cariados. Se ha visto que resinas compuestas no poseen actividad antibacteriana, por lo que no impedirían el crecimiento de S.mutans sobre ellas. Además se han identificado específicamente S.mutans en márgenes de resinas compuestas. Se ha descrito que la amalgama posee actividad antibacteriana, por lo que se esperaría un menor desarrollo de S.mutans sobre ella en relación a resinas compuestas. Esta investigación planteó como hipótesis que “Existe mayor cantidad de Unidades Formadoras de Colonias de S. mutans y S. sobrinus en el margen de restauraciones oclusales de resina compuesta que en el margen de restauraciones oclusales de amalgama” y se propuso como objetivo general “Determinar el porcentaje de unidades formadoras de colonias de S. mutans y S. sobrinus en el margen de restauraciones directas oclusales de resina compuesta y de amalgama con el fin de evaluar el efecto de ambos materiales sobre el crecimiento de estas especies bacterianas.” Se seleccionaron 25 pacientes adultos de alto riesgo cariogénico, que portaran una amalgama oclusal y otros 25 pacientes que portaran una resina compuesta oclusal. Se obtuvo una muestra de placa bacteriana supragingival del margen de todas las restauraciones y se realizaron cultivos en agar TYCSB (medio selectivo) y agar sangre Columbia (medio no selectivo). Al analizar los resultados se pudo observar que no hubo diferencias significativas en el crecimiento de S. mutans sobre ambos materiales. No se detectó S.sobrinus en los pacientes, en base a la prueba de la Esculina.
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Thern, Anette. "Interactions between Streptococcus pyogenes and the human immune system with special reference to C4b-binding protein /." Lund : Dept. of Medical Microbiology, Lund University, 1998. http://catalog.hathitrust.org/api/volumes/oclc/39224761.html.
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Law, Vicky Wai-Kee. "Oral colonization of mutans streptococci in young children : a longitudinal study /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19176.pdf.
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Khan, Izhar-ul-Haq. "Identification and further characterization of Streptococcus uberis and Streptococcus parauberis isolated from bovine milk samples." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964881799.
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Rouse, Natalie M. "Interactions of Streptococcus infantarius ss coli and Streptococcus phocae in Resurrection and Kachemak Bays, Alaska." Thesis, University of Alaska Anchorage, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10784789.
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The United States Fish and Wildlife service declared an unusual mortality event (UME) in 2006 when a high number of northern sea otters in Alaska were found dead beginning in 2002. Necropsies revealed the cause of death in 30% of cases to be septicemia with meningoencephalitis and/or vegetative valvular endocarditis (VVE) colonized by gram positive cocci, later determined to be primarily Streptococcus infantarius ss coli and Streptococcus phocae. While much work has been done to uncover the pathogenic agents responsible for these deaths in northern sea otters, the ecology of S. infantarius ss coli and S. phocae in the environment remains poorly understood. This study investigated the presence of S. infantarius ss coli and S. phocae in the marine environment by 1) developing a molecular method to detect S. infantarius ss coli 2) examining potential microbe-habitat associations in Kachemak Bay and Resurrection Bay, Alaska, and 3) determining the competency of otter prey species to act as reservoirs for these pathogens. A PCR assay was developed to detect the sodA gene of S. infantarius ss coli in both environmental and clinical samples. Water and bay mussels were collected from sites in Kachemak and Resurrection Bays and pathogen presence was determined using PCR. Habitat attributes were recorded onsite and determined using ShoreZone. Prey competency was determined via a dosing experiment in the lab. Our primer set for the S. infantarius ss coli sodA gene, as well as a previously published primer set for the S. phocae sodA gene, successfully identified our targets in clinical and environmental samples using conventional PCR. Primer sets we designed successfully quantified the sodA gene of S. infantarius ss coli and/or S. phocae in environmental samples and in dosed prey samples using qPCR. S. infantarius ss coli and/or S. phocae were present in water or mussels at 61 of 162 sites. Statistical analyses to determine bacterial correlations with habitat attributes revealed some correlations between habitat parameters selected and presence of our target bacteria in the environment. Prey competency experiments showed that bivalves were the most competent pathogen reservoirs. Results of this study will inform microbial ecologists and wildlife managers of the potential environmental risk factors for S. infantarius ss coli and S. phocae infection as well as provide information about pathogenic bacterial presence in the marine environment.
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Becerra, Martínez José Luis Elías. "Obtención de una proteína recombinante PsaA de Streptococcus pneumoniae, homóloga a una de Streptococcus equi." Tesis, Universidad de Chile, 2005. http://repositorio.uchile.cl/handle/2250/130773.
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Memoria para optar al Título Profesional de Médico VeterinarioLos streptococos patógenos para los equinos incluyen S. equi subsp. equi (S. equi), S. equi subsp. zooepidemicus, S. dysgalactiae subsp. equisimilis y S. pneumoniae cápsula Tipo III. S. equi causa gurma, una linfoadenitis purulenta altamente contagiosa que afecta a los miembros de la familia Equidae. Rápidos progresos se han realizado para la identificación de factores de virulencia y proteínas de S. equi. La mayoría de éstas son expresadas en la superficie bacteriana o son secretadas. Se ha demostrado la presencia de una proteína homóloga a la pneumococcal surface adhesin A (PsaA) de S. pneumoniae, en S. zooepidemicus y S. equi. La PsaA de S. pneumoniae, como otras proteínas, es inmunogénica y protege animales de laboratorio ante un desafío con neumococos. El objetivo de esta memoria fue obtener desde un aislado clínico de S. pneumoniae, una PsaA recombinante purificada desde E. coli BL21DE3. La metodología consistió en amplificar el gen PsaA por PCR y ligarlo al plasmidio de clonamiento (pETBlue-1), luego con la mezcla de ligación PsaA/pSTBlue-1 se transformó la cepa E. coli DH5; de las colonias transformadas, se purificó el plasmidio (PsaA/pSTBlue-1) por lisis alcalina, el cual fue sometido a digestión doble y, el fragmento liberado, fue ligado finalmente a un vector de expresión (pET-15b). Con la mezcla de ligación PsaA/pET-15b, se transformó la cepa E. coli BL21DE3, que expresó una proteína fusionada a una cola de histidina; la proteína fusionada, a su vez, se purificó en una columna con afinidad por histidina (Ni-Nta). La presencia de rPsaA fue analizada mediante electroforesis en gel de poliacrilamida y por Western blot, observándose la presencia de una proteína de 37 kDa., con la que reaccionó específicamente el anticuerpo policlonal de conejo anti His-tag. La secuencia nucleotídica del fragmento fue comparada en la base de datos BLAST (www.ncbi.nlm.nih.gov), encontrándose un 98% de identidad con la cepa S. pneumoniae R6. Además se identificaron cuatro regiones, con identidades superiores al 80%, similares a las del gen parcial mba de la proteína ligadora de metal/adhesina de S. equi, homóloga a PsaA de S. pneumoniae. El producto obtenido permitirá realizar estudios de formulación y evaluación, en modelo animal, de un prototipo de vacuna contra el gurma, basado en la proteína PsaA de S. pneumoniae.
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Heather, Zoe. "Comparative and functional genomic analysis of Streptococcus equi and Streptococcus zooepidemicus : identifying novel vaccine targets." Thesis, Open University, 2009. http://oro.open.ac.uk/54823/.
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Streptococcus equi subspecies equi (S. equi) is a host-restricted pathogen of horses and the aetiological agent of strangles. Available evidence suggests that S. equi evolved from Streptococcus equi subspecies zooepidemicus (S. zooepidemicus), a versatile bacterium that is often isolated from the equine respiratory tract, but can cause opportunistic disease in horses and other animals. A comparison of the genomes of S. equi 4047 and S. zooepidemicus H70 and the screening of diverse S. equi and S. zooepidemicus strains uncovered the genetic events that have shaped the evolution of S. equi, and led to its emergence as a niche-adapted pathogen. This analysis provides evidence of functional loss, changes in the organisation and sequence of genes, and pathogenic specialisation through the acquisition of prophage encoding a phospholipase A2 toxin, and 4 superantigens, and an integrative conjugative element carrying a novel siderophore-like nonribosomal peptide synthetase (NRPS) system. The NRPS shares similarity with the yersiniabactin system found in the high pathogenicity island of Yersinia pestis and is the first of its kind to be identified in streptococci. As this genetic feature is absent from the S. zooepidemicus population, its gain is considered to have been a key event in the emergence of S. equi. Further work determined a role for the NRPS in iron acquisition, and through its heterologous reconstitution in Escherichia coli and/or the analysis of allelic replacement mutants in S. equi, identified biosynthetic genes, transporters involved in efflux and import of the NRPS product(s), salicylate as a substrate for the NRPS and its regulation by a novel iron-dependent IdeR-like repressor, using various in vitro growth assays, including sensitivity to streptonigrin and 55Fe accumulation. Possible vaccine targets were identified in both subspecies and existing diagnostic tools were improved, which included the development of a quantitative PCR test for the detection of S. equi.
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Loimaranta, Vuokko. "Generation and evaluation of efficiency of bovine immune colostrum against Streptococcus mutans and Streptococcus sobrinus." Turku : Turun Yliopisto, 1999. http://catalog.hathitrust.org/api/volumes/oclc/42755125.html.
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Veras, Idia Nara de Sousa. "Análise do perfil morfológico de candida tropicalis durante a formação do biofilme sob influência de metabólitos extracelulares de bactérias do gênero Streptococcus." reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/18054.
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VERAS, I. N. Análise do perfil morfológico de candida tropicalis durante a formação do biofilme sob influência de metabólitos extracelulares de bactérias do gênero Streptococcus. 2014. 77 f. Dissertação ( Mestrado em Biotecnologia) - Campus de Sobral, Universidade Federal do Ceará, Sobral, 2014.Submitted by Djeanne Costa (djeannecosta@gmail.com) on 2016-06-29T14:58:00Z No. of bitstreams: 1 2014_dis_insveras.pdf: 2042523 bytes, checksum: adf18ca2b4b9df61f42a9d6cff04ce95 (MD5)
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Bacteria and fungi are found together in a multitude of environments, and particularly in the form of biofilm adherent species which interact through various signaling mechanisms. In the oral cavity, Candida species coexist with numerous bacterial species, and evidence suggests that bacteria can modulate biofilm formation as well as induce the formation of hyphae. Thus, to characterize such interactions are essential to the understanding of pathogenesis of diseases and possibly the discovery of new therapeutic strategies. In this sense, the main objective of this study was to evaluate, in vitro, the mechanisms involved in the interaction between bacteria Streptococcus oralis, Streptococcus sanguinis, and Streptococcus parasanguinis yeast Candida tropicalis. In the study the effect of extracellular metabolites present in the supernatant of C. tropicalis (SCT) on the pre-formed biofilm (6H) S. oralis, S. sanguinis and S. parasanguinis was analyzed. The effect of extracellular metabolites of S. oralis (SSO), S. sanguinis (SSS) and S. parasanguinis (SSP) on planktonic growth and biofilm
Bactérias e fungos são encontrados juntos em uma infinidade de ambientes e, particularmente, na forma de biofilme, onde as espécies aderentes interagem através de diversos mecanismos de sinalização. Na cavidade oral, espécies de Candida coexistem com inúmeras espécies bacterianas, e evidências sugerem que bactérias podem modular a formação de biofilme, bem como induzir a formação de hifas e pseudo-hifas. Assim, caracterizar tais interações é essencial para o entendimento da patogênese das doenças e, possivelmente, a descoberta de novas estratégias terapêuticas. Nesse sentido, o objetivo principal deste trabalho foi avaliar, in vitro, os mecanismos envolvidos na interação entre as bactérias Streptococcus oralis, Streptococcus sanguinis, Streptococcus parasanguinis e a levedura Candida tropicalis. No estudo foi analisado o efeito dos metabólitos extracelulares presentes no sobrenadante de C. tropicalis (SCT) sobre o biofilme pré-formado (6h) de S. oralis, S. sanguinis e S. parasanguinis. Também foi avaliado o efeito dos metabólitos extracelulares de S. oralis (SSO), S. sanguinis (SSS) e S. parasanguinis (SSP) sobre o crescimento planctônico, formação de biofilme e capacidade de filamentação de C. tropicalis, utilizando apenas o sobrenadante da cultura de cada um dos estreptococos em diferentes concentrações (100, 50 e 25%). Além disso, foi analisado o efeito dos metabólitos extracelulares dos estreptococos sobre o biofilme pré-formado (6h) de C. tropicalis. Para verificar o efeito dos metabólitos extracelulares foram utilizados dois métodos: o método turbidimétrico que se baseia na leitura da densidade óptica (OD) das suspensões celulares e a coloração cristal violeta (CV) que permite a quantificação indireta da formação de biofilme através da coloração com cristal violeta. Em seguida, foram examinadas as características dos biofilmes, formados por 24 horas, através da análise por microscopia óptica comum. Os resultados referentes ao biofilme foram submetidos ao ANOVA com pós-teste Bonferroni, com diferença estatística de p<0,01. Nossos resultados sugerem que substâncias solúveis produzidas por S. oralis, S. sanguinis e S. parasanguinis induzem a formação de hifas de C. tropicalis sem interferir no crescimento planctônico. Além de diminuir drasticamente o desenvolvimento do biofilme dessa levedura quando em contato com SSS e SSP. Tal fato reforça a ideia de que existe grande heterogeneidade dentro de biofilmes polimicrobianos, especialmente entre leveduras e bactérias. E que o resultado dessa interação depende das condições as quais estes micro-organismos serão submetidos.
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Featherstone, Zoe L. "Investigations into the pathogenesis of aquatic Streptococcus agalactiae and Streptococcus iniae in Nile tilapia (Oreochromis niloticus)." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/21633.
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The bacterial pathogens Streptococcus agalactiae and S. iniae have the capacity to infect a wide range of fish species throughout the world, with Nile tilapia (Oreochromis niloticus) being particularly susceptible. Global tilapia aquaculture production was estimated to be 3.5 million tonnes in 2008, and has a significant contribution in the global farmed fish market. Due to their ability to adapt to a wide range of culture systems the commercialisation of tilapia production has occurred in more than 100 countries. However, countries such as China have suffered from severe and extensive outbreaks of streptococcosis in cultured tilapia continuously for many years. Such large-scale outbreaks in China have resulted in a loss of approximately US$0.4 billion in 2011. Fish are permanently exposed to a plethora of pathogens and natural disease outbreaks are complex host-pathogen interactions that seldom involve single pathogen infections. As a consequence, simultaneous infections, alternatively called concurrent or co-infections, are starting to receive interest from aquatic disease researchers. Streptococcus agalactiae and S. iniae infections can both occur in the same geographic area and both S. agalactiae and S. iniae have been found to be present on the same farm in a single disease outbreak. It has been found that a disease outbreak caused by one these pathogens can be followed by another outbreak from the other. These two pathogens have serious effects on the tilapia aquaculture industry yet there is no information regarding S. agalactiae and S. iniae co-infections. Such information would be valuable for understanding epidemiology and the development of improved treatment and control of aquatic streptococcosis infections. The overall aim of this study was to investigate the pathogenesis of S. agalactiae and S. iniae in Nile tilapia. One important aspect of investigating simultaneous infections was to examine if there was any competition or synergy between S. agalactiae and S. iniae in vitro or in vivo. It was found that competition between S. agalactiae and S. iniae in vitro was inconsistent between different experimental systems. Results indicated that there was either no interaction between bacterial species or they coexisted during in vitro competition assays. Whereas, an in vivo model utilising wax moth larvae (Galleria mellonella) suggested that during a simultaneous infection with S. agalactiae and S. iniae the total levels of larval mortality were lower than expected indicating that the pathogens may have interacted with one another in a competitive manner. Investigations were also conducted to identify the expression of virulence factors in vitro for S. agalactiae and S. iniae. Comparisons were then made to ascertain any inter- and intra-species variation. Results demonstrated that both S. agalactiae and S. iniae strains possessed a capsule but varied in their haemolytic activity, blood survival and resistance to complement-mediated killing. These variations suggested that the two bacterial species differed in their mechanisms of pathogenicity where aquatic S. agalactiae strains may initially have a more systemic spread of infection and aquatic S. iniae strains may utilise a more localised spread of infection within the host. This hypothesis was tested through the development of a robust and reliable challenge model for S. agalactiae and S. iniae in Nile tilapia. Through this work it was apparent that fish infected with S. iniae experienced an acute infection with morbidity/mortality occurring 1 – 3 days after exposure. Whereas, the S. agalactiae challenged fish showed a more chronic infection with morbidity/mortality occurring from 1 – 6 days after exposure. Findings clearly demonstrated a more systemic spread of infection during a S. agalactiae challenge with high bacterial loads in all the organs examined. Streptococcus iniae was observed in fewer organs of infected fish and bacterial numbers were substantially lower. Concurrent infections are complex in natural conditions and in experimental studies. As a result a substantial amount of research will be required to fully understand the nature of co-infection with these two streptococci. This study has provided a solid foundation upon which to base future work.
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Sauerbier, Julia [Verfasser], and Regine [Akademischer Betreuer] Hakenbeck. "Horizontaler Gentransfer zwischen Streptococcus mitis und Streptococcus pneumoniae : Analyse der Resistenzentwicklung / Julia Sauerbier. Betreuer: Regine Hakenbeck." Kaiserslautern : Universitätsbibliothek Kaiserslautern, 2012. http://d-nb.info/1021929638/34.
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BOUNAIX, STEPHANE. "Taxinomie biochimique, physiologique et moleculaire d'une collection de souches de streptococcus thermophilus et de streptococcus salivarius." Caen, 1992. http://www.theses.fr/1992CAEN2019.
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L'etude d'une collection de 27 souches de streptococcus thermophilus et de 11 souches de streptococcus salivarius avait deux objectifs: d'une part, determiner les differences existant entre un ensemble de 20 souches proches de la souche-type (groupe a) ayant un profil fermentaire de 3 a 5 caracteres positifs et un groupe de 8 souches atypiques de streptococcus thermophilus (groupe b) ayant un profil fermentaire de plus de 17 caracteres positifs, d'autre part rechercher des differences significatives entre les deux sous-especes ou especes. De l'etude d'hybridation quantitative adn-adn en milieu liquide, il ressort que 7 souches atypiques sont etroitement liees a la souche-type. Les profils des proteines solubles totales confirment cette proximite. Par analyse discriminante, la spectrometrie infrarouge par transformee de fourier montre que les souches du groupe b appartiennent au meme ensemble que celles du groupe a. Elles se distinguent de la souche-type par un taux de croissance eleve a 45c, l'absence d'activite ureasique et des profils electrophoretiques plus complexes en champ pulse. Aucun rapprochement n'est possible entre les souches atypiques et les souches de streptococcus salivarius. Par hybridation quantitative adn-adn en milieu liquide et spectrometrie infrarouge par transformee de fourier, il s'avere que les deux especes streptococcus thermophilus et streptococcus salivarius sont distinctes. Les autres techniques utilisees (profil biochimique api50, activite ureasique, taux de croissance en fonction de la temperature, profil electrophoretique de l'adn en champ pulse et profil des proteines solubles totales) mettent en evidence l'heterogeneite du groupe de souches de streptococcus salivarius