The Experts below are selected from a list of 1770 Experts worldwide ranked by ideXlab platform

David Beighton - One of the best experts on this subject based on the ideXlab platform.

  • A Conserved Region of a Hyaluronidase Gene from Streptococcus intermedius
    Advances in experimental medicine and biology, 1997
    Co-Authors: Hla Shain, Karen A. Homer, Joe Aduse-opoku, David Beighton
    Abstract:

    Streptococcus intermedius of the “Streptococcus milleri group” has been associated with liver and brain abscesses2, 5, 6. Homer et al. (1994) have suggested that the production of hyaluronidase is a potential virulence determinant by virtue of its ability to degrade the host extracellular matrix and release sugars which can be utilised as nutrients thus facilitating bacterial proliferation1.

  • Purification and properties of a novel glycosaminoglycan depolymerase from Streptococcus intermedius strain UNS 35.
    Journal of medical microbiology, 1996
    Co-Authors: H. Shain, Karen A. Homer, David Beighton
    Abstract:

    A glycosaminoglycan (GAG) depolymerase that acts on chondroitin sulphate A (CS-A), chondroitin sulphate C (CS-C) and hyaluronic acid (HA) was purified to apparent homogeneity from a culture of Streptococcus intermedius, strain UNS 35, grown in minimal medium supplemented with CS-A as the sole carbon source. The enzyme was purified by ammonium sulphate precipitation followed by serial chromatography on DEAE Trisacryl M, CM Trisacryl M and heparin-agarose. SDS-PAGE analysis of the purified enzyme yielded a single band with a mol. wt of c. 83 000. The purified GAG depolymerase was unusual in its substrate specificity. The enzyme was initially regarded as a CS depolymerase because of its induction by CS-A. However, the GAG depolymerase exhibited greatest activity against HA, whereas the degradation rates of CS-A and CS-C were c. 8% and 2%, respectively, of the rate with HA. On this basis the enzyme could be classified as a hyaluronidase rather than a CS depolymerase. The pH optimum was around neutrality and the enzyme was unusual in having a high pl of approximately 9.3.

  • Degradation and utilisation of chondroitin sulphate by Streptococcus intermedius.
    Journal of medical microbiology, 1996
    Co-Authors: H. Shain, Karen A. Homer, David Beighton
    Abstract:

    Streptococcus intermedius, part of the ‘Streptococcus milleri group’, has the ability to produce glycosaminoglycan depolymerising enzymes (hyaluronidase and chrondroitin sulphate depolymerase) which is unique amongst the viridans streptococci and may contribute to their virulence in brain and liver abscesses. The growth of S. intermedius strain UNS 35 was studied in basal medium supplemented with chondroitin sulphate A (CS-A, sulphated at position 4 of the N-acetylgalactosamine moiety) or chondroitin sulphate C (CS-C, sulphated at position 6 of the N-acetylgalactosamine moiety) as the major carbohydrate source. CS-A but not CS-C supported the growth of S. intermedius. Extracellular degradation of CS-A resulted in the initial accumulation of 2-acetamido-2-deoxy-3-O-(β-D-gluco-4-δenepyranosyluronic acid)-D-galactose (δUA GalNAc-0S), and low levels of 2-acetamido-2-deoxy-3-O-(β-D-gluco-4-δenepyranosyl uronic acid)-4-O-sulpho-D-galactose (δUA GalNAc-4S) in the medium with GalNAc-0S being subsequently utilised during bacterial growth. Metabolic end-products included formate and ethanol but not lactate, indicating that growth was probably carbon-limited. The CS-A contained 30% CS-C, which was also depolymerised resulting in the formation of 2-acetamido-2-deoxy-3-O-(β-D-gluco-4-δenepyranosyluronic acid)-6-O-sulpho-D-galactose (δUA GalNAc-6S) in the culture supernate, but this unsaturated disaccharide was apparently not utilised during growth. The results indicate that S. intermedius produced CS-AC depolymerase, which was inducible and extracellular, and sulphatase activity. Experiments with authentic δUA GalNAc-4S and δUA GalNAc-6S demonstrated that δUA GalNAc-4S rather than δUA GalNAc-6S was the preferred substrate for the sulphatase. Therefore, it is suggested that the CS-AC depolymerase of S. intermedius may play a role in the destruction of CS in host tissues, facilitating bacterial spread, and also in bacterial nutrition by the liberation of nutrients at the site of infection.

  • Production of specific glycosidase activities by Streptococcus intermedius strain UNS35 grown in the presence of mucin.
    Journal of medical microbiology, 1994
    Co-Authors: K. A. Homer, Robert A. Whiley, David Beighton
    Abstract:

    An isolate of Streptococcus intermedius from a brain abscess showed neuraminidase (sialidase), beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and N-acetyl-beta-D-galactosaminidase activities. The optimal pH values of these enzymes were 5.5-6.0, 5.5-6.0, 5.0-5.5 and 5.0-5.5, respectively. The km of the enzymes varied according to whether the type of substrate was chromogenic or fluorogenic; sialidase was most active at the lowest substrate concentrations, with a km of 0.01 mM. In semi-defined medium, with porcine gastric mucin--a model glycoprotein--as the sole source of fermentable carbohydrate, levels of the glycosidases were significantly increased. Addition of glucose to the mucin-containing medium, or growth of cells in media supplemented with glucose alone, repressed glycosidic activities and the majority of these were cell-associated. S. intermedius cells from cultures grown with mucin were able, simultaneously, to transport via sugar:phosphoenolpyruvate phosphotransferase (PTS) systems, monosaccharides which are constituents of carbohydrate side chains of glycoproteins. These cells also possessed significant levels of neuraminate-pyruvate lyase, involved in the intracellular catabolism of neuraminic acid; this was absent from cells grown with glucose. These mechanisms, collectively, may facilitate the persistence and growth of S. intermedius in vivo.

  • Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus (the Streptococcus milleri group): association with different body sites and clinical infections.
    Journal of clinical microbiology, 1992
    Co-Authors: Robert A. Whiley, David Beighton, T. G. Winstanley, H Y Fraser, J. M. Hardie
    Abstract:

    The associations of Streptococcus intermedius, S. constellatus, and S. anginosus (the three species of the S. milleri group) with clinical infections and sites of isolation were investigated by using a simple biochemical scheme to identify a collection of 153 clinical isolates. S. intermedius was associated with abscesses of the brain and liver, while both S. anginosus and S. constellatus were isolated from a wider range of sites and infections. S. anginosus strains predominated in both genitourinary and gastrointestinal sources and exhibited a wider range of phenotypes, particularly in the ability to ferment mannitol and/or raffinose.

Robert A. Whiley - One of the best experts on this subject based on the ideXlab platform.

  • Role of catabolite control protein A in the regulation of intermedilysin production by Streptococcus intermedius.
    Infection and immunity, 2010
    Co-Authors: Toshifumi Tomoyasu, Robert A. Whiley, Atsushi Tabata, Hidenori Imaki, Riki Hiroshima, Sachiko Masuda, Joseph Aduse-opoku, Ken Kikuchi, Keiichi Hiramatsu, Hideaki Nagamune
    Abstract:

    Streptococcus intermedius is an opportunistic pathogen of humans that causes purulent infections, including brain and liver abscesses. This pathogen secretes a human-specific cytolysin, intermedilysin, which has been recognized as a major virulence factor. However, most of the expressional control mechanisms of ily are still unknown. To determine these mechanisms, we analyzed the nucleotide sequence of the ily promoter region. We found a highly homologous region to the catabolite-repressible element (cre) in the ily promoter region and observed a considerable decrease in the amount of secreted intermedilysin when cells were grown in a culture medium containing high concentrations of glucose/utilizable carbohydrates. Disruption of the ccpA gene, which encodes catabolite control protein A, did not induce catabolite repression of ily by glucose/utilizable carbohydrates. In cre mutants, catabolite repression of ily was partially restored, and purified catabolite control protein A bound to an oligonucleotide containing the cre consensus sequence in the ily promoter region. In addition, a prolonged lag phase and slower doubling time of the ccpA mutant cells were observed. Our data show that S. intermedius can modulate ily expression and growth rate through catabolite control protein A-mediated monitoring of the extracellular glucose/utilizable carbohydrate concentration.

  • Effect on polymorphonuclear cell function of a human-specific cytotoxin, intermedilysin, expressed by Streptococcus intermedius.
    Infection and immunity, 2001
    Co-Authors: M. G. Macey, Robert A. Whiley, L. Miller, Hideaki Nagamune
    Abstract:

    Streptococcus intermedius is a member of the normal flora of the mouth but is also an opportunistic pathogen associated with purulent infections at oral and nonoral sites. Intermedilysin (ILY) has been shown to be a cytolysin capable of generating pores in the cell membrane of erythrocytes demonstrable by electron microscopy. This effect has been shown to be specific for human cells. Since polymorphonuclear cells (PMNs) are the main cell involved in innate immunity we investigated the effect of purified intermedilysin from Streptococcus intermedius on PMN function. Active ILY at a concentration of 40 ng/μl caused a significant decrease in the number of intact PMNs after 60 min. The active cytolysin, when compared with heat-inactivated ILY, did not appear to be chemotactic for the PMNs but did cause an increase in intracellular calcium, with increased cell surface CD11b expression, metabolic burst, and phagocytosis of Staphylococcus aureus. These findings may have implications for the role of ILY in deep-seated abscesses.

  • A Cytolytic Toxin Specific for Human Cells of a Streptococcus intermedius Isolated from Human Liver Abscess
    1997
    Co-Authors: Hideaki Nagamune, Robert A. Whiley, C. Ohnishi, A. Katsuura, Y. Taoka, K. Fushitani, K. Yamashita, Akihiko Tsuji, Yoshiko Matsuda, T. Maeda
    Abstract:

    Streptococcus intermedius is one of the three distinct species classified into the Streptococcus milleri-group(SMG, S. anginosus, S. constel/atus and S. intermedius) which constitutes a portion of the normal flora of the human oral cavity, as well as the upper respiratory, gastrointestinal and female urogenital tracts, and it can cause purulent infections in the mouth and internal organs. Recently, S. intermedius has been found to be associated with brain and liver abscesses3• However, the pathogenic factors of S. intermedius have not been sufficiently characterized despite their clinical importance. Several Streptococcus species such as S. pyogenes and S. pneumoniae are hemolytic and produce the cytotoxins streptolysin 0 and pneumolysin, respectively. These cytotoxins directly damage host tissues and defense cells and participate in bacterial pathogenicity. They are effective on various animal cells, such as sheep, rabbit and horse erythrocytes as well as on human cells2• However, since almost all strains of S. intermedius did not show significant hemolysis on the horse or sheep blood agar, the cytotoxin of this species has not been studied. Recently, we found a cytolytic toxin (intermedilysin) specific for human cells secreted from a strain of this species isolated from a human liver

  • Production of specific glycosidase activities by Streptococcus intermedius strain UNS35 grown in the presence of mucin.
    Journal of medical microbiology, 1994
    Co-Authors: K. A. Homer, Robert A. Whiley, David Beighton
    Abstract:

    An isolate of Streptococcus intermedius from a brain abscess showed neuraminidase (sialidase), beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and N-acetyl-beta-D-galactosaminidase activities. The optimal pH values of these enzymes were 5.5-6.0, 5.5-6.0, 5.0-5.5 and 5.0-5.5, respectively. The km of the enzymes varied according to whether the type of substrate was chromogenic or fluorogenic; sialidase was most active at the lowest substrate concentrations, with a km of 0.01 mM. In semi-defined medium, with porcine gastric mucin--a model glycoprotein--as the sole source of fermentable carbohydrate, levels of the glycosidases were significantly increased. Addition of glucose to the mucin-containing medium, or growth of cells in media supplemented with glucose alone, repressed glycosidic activities and the majority of these were cell-associated. S. intermedius cells from cultures grown with mucin were able, simultaneously, to transport via sugar:phosphoenolpyruvate phosphotransferase (PTS) systems, monosaccharides which are constituents of carbohydrate side chains of glycoproteins. These cells also possessed significant levels of neuraminate-pyruvate lyase, involved in the intracellular catabolism of neuraminic acid; this was absent from cells grown with glucose. These mechanisms, collectively, may facilitate the persistence and growth of S. intermedius in vivo.

  • Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus (the Streptococcus milleri group): association with different body sites and clinical infections.
    Journal of clinical microbiology, 1992
    Co-Authors: Robert A. Whiley, David Beighton, T. G. Winstanley, H Y Fraser, J. M. Hardie
    Abstract:

    The associations of Streptococcus intermedius, S. constellatus, and S. anginosus (the three species of the S. milleri group) with clinical infections and sites of isolation were investigated by using a simple biochemical scheme to identify a collection of 153 clinical isolates. S. intermedius was associated with abscesses of the brain and liver, while both S. anginosus and S. constellatus were isolated from a wider range of sites and infections. S. anginosus strains predominated in both genitourinary and gastrointestinal sources and exhibited a wider range of phenotypes, particularly in the ability to ferment mannitol and/or raffinose.

Hideaki Nagamune - One of the best experts on this subject based on the ideXlab platform.

  • Role of Streptococcus intermedius DnaK chaperone system in stress tolerance and pathogenicity
    Cell Stress and Chaperones, 2012
    Co-Authors: Toshifumi Tomoyasu, Atsushi Tabata, Hidenori Imaki, Keigo Tsuruno, Aya Miyazaki, Kenji Sonomoto, Robert Alan Whiley, Hideaki Nagamune
    Abstract:

    Streptococcus intermedius is a facultatively anaerobic, opportunistic pathogen that causes purulent infections and abscess formation. The DnaK chaperone system has been characterized in several pathogenic bacteria and seems to have important functions in stress resistance and pathogenicity. However, the role of DnaK in S. intermedius remains unclear. Therefore, we constructed a dnaK knockout mutant that exhibited slow growth, thermosensitivity, accumulation of GroEL in the cell, and reduced cytotoxicity to HepG2 cells. The level of secretion of a major pathogenic factor, intermedilysin, was not affected by dnaK mutation. We further examined the function and property of the S. intermedius DnaK chaperone system by using Escherichia coli Δ dnaK and Δ rpoH mutant strains. S. intermedius DnaK could not complement the thermosensitivity of E. coli Δ dnaK mutant. However, the intact S. intermedius DnaK chaperone system could complement the thermosensitivity and acid sensitivity of E. coli Δ dnaK mutant. The S. intermedius DnaK chaperone system could regulate the activity and stability of the heat shock transcription factor σ^32 in E. coli , although S. intermedius does not utilize σ^32 for heat shock transcription. The S. intermedius DnaK chaperone system was also able to efficiently eliminate the aggregated proteins from Δ rpoH mutant cells. Overall, our data showed that the S. intermedius DnaK chaperone system has important functions in quality control of cellular proteins but has less participation in the modulation of expression of pathogenic factors.

  • Role of catabolite control protein A in the regulation of intermedilysin production by Streptococcus intermedius.
    Infection and immunity, 2010
    Co-Authors: Toshifumi Tomoyasu, Robert A. Whiley, Atsushi Tabata, Hidenori Imaki, Riki Hiroshima, Sachiko Masuda, Joseph Aduse-opoku, Ken Kikuchi, Keiichi Hiramatsu, Hideaki Nagamune
    Abstract:

    Streptococcus intermedius is an opportunistic pathogen of humans that causes purulent infections, including brain and liver abscesses. This pathogen secretes a human-specific cytolysin, intermedilysin, which has been recognized as a major virulence factor. However, most of the expressional control mechanisms of ily are still unknown. To determine these mechanisms, we analyzed the nucleotide sequence of the ily promoter region. We found a highly homologous region to the catabolite-repressible element (cre) in the ily promoter region and observed a considerable decrease in the amount of secreted intermedilysin when cells were grown in a culture medium containing high concentrations of glucose/utilizable carbohydrates. Disruption of the ccpA gene, which encodes catabolite control protein A, did not induce catabolite repression of ily by glucose/utilizable carbohydrates. In cre mutants, catabolite repression of ily was partially restored, and purified catabolite control protein A bound to an oligonucleotide containing the cre consensus sequence in the ily promoter region. In addition, a prolonged lag phase and slower doubling time of the ccpA mutant cells were observed. Our data show that S. intermedius can modulate ily expression and growth rate through catabolite control protein A-mediated monitoring of the extracellular glucose/utilizable carbohydrate concentration.

  • Sialidase of Streptococcus intermedius: a putative virulence factor modifying sugar chains
    Microbiology and immunology, 2010
    Co-Authors: Ayuko Takao, Hideaki Nagamune, Nobuko Maeda
    Abstract:

    A sialidase gene of Streptococcus intermedius was cloned. It was most similar to nanA, a major sialidase gene in Streptococcus pneumoniae, and was expressed in Escherichia coli. Since the gene-knockout S. intermedius strain lost detectable sialidase activity, the gene might code, either solely or mainly, the glycosidase in the bacterial genome. Polymerase chain reaction using the primers for the nanA homologue in S. intermedius (described as nanA below) showed that this sialidase gene was commonly distributed within the isolates of S. intermedius, but not found in the strains of other species among the anginosus group. In biofilm formation assay under cultivation with mucin, the nanA-deleted S. intermedius maintained the amount of biofilm for 72 hr, while that of the parent strain decreased during incubation from 24 to 72 hr. Since sialidase activity in the parent strain increased during that time period, sialidase might contribute to the degradation of biofilm under sialic acid-rich conditions. When S. intermedius was added into the HepG2 hepatoma culture, the calculated disassociation constant (K(d)) of EDTA-releasable bacterial adhesion to the cells was higher in the nanA-deleted strain than in the parent. Furthermore, the rate constant, assuming endocytosis of the bacterium mediated by ASGP-R in HepG2 cells, seemed to be increased by sialidase pretreatment of the bacterial cells before addition to the cell culture. According to the results, modification of sugar chains by sialidase on the bacterial surface and in the surrounding environment might influence both bacterial interaction and host-bacterial interaction in S. intermedius.

  • Rapid identification of Streptococcus intermedius by PCR with the ily gene as a species marker gene.
    Journal of medical microbiology, 2002
    Co-Authors: Takatsugu Goto, Hideaki Nagamune, Aiko Miyazaki, Yoshiaki Kawamura, Ooki Ohnishi, Kanako Hattori, Kazuto Ohkura, Kazuaki Miyamoto, Shigeru Akimoto, Takayuki Ezaki
    Abstract:

    Streptococcus intermedius belongs to the anginosus group of streptococci (AGS) and is associated with endogenous infections leading to abscesses in the oral cavity and at deep-seated sites, such as the brain and liver. Two other species, S. anginosus and S. constellatus, and some presently unnamed taxa, are also classified as AGS. Recently, S. constellatus subsp. pharyngis, a new subspecies with biochemical characteristics similar to S. intermedius, was described with the potential for causing confusion when trying to identify isolates of these two species routinely with commercial identification kits, such as Rapid ID32 Strep and Fluo-Card Milleri. To correctly identify S. intermedius, this study attempted to develop an accurate PCR identification system with the ily gene as a species marker. This approach relies on amplification of an 819-bp fragment of the ily gene and its 3′-flanking region and is shown here to be specific for S. intermedius strains among all other streptococcal species. Moreover, this PCR system was applicable in direct rapid PCR with whole bacterial cells and TaKaRa Z-Taq TM (TaKaRa), a highly efficient DNA polymerase, as the template and DNA amplification enzyme, respectively.

  • Effect on polymorphonuclear cell function of a human-specific cytotoxin, intermedilysin, expressed by Streptococcus intermedius.
    Infection and immunity, 2001
    Co-Authors: M. G. Macey, Robert A. Whiley, L. Miller, Hideaki Nagamune
    Abstract:

    Streptococcus intermedius is a member of the normal flora of the mouth but is also an opportunistic pathogen associated with purulent infections at oral and nonoral sites. Intermedilysin (ILY) has been shown to be a cytolysin capable of generating pores in the cell membrane of erythrocytes demonstrable by electron microscopy. This effect has been shown to be specific for human cells. Since polymorphonuclear cells (PMNs) are the main cell involved in innate immunity we investigated the effect of purified intermedilysin from Streptococcus intermedius on PMN function. Active ILY at a concentration of 40 ng/μl caused a significant decrease in the number of intact PMNs after 60 min. The active cytolysin, when compared with heat-inactivated ILY, did not appear to be chemotactic for the PMNs but did cause an increase in intracellular calcium, with increased cell surface CD11b expression, metabolic burst, and phagocytosis of Staphylococcus aureus. These findings may have implications for the role of ILY in deep-seated abscesses.

J. M. Hardie - One of the best experts on this subject based on the ideXlab platform.

Peter B. Soeters - One of the best experts on this subject based on the ideXlab platform.

  • Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedius. Clinical relevance, hemolytic and serologic characteristics.
    American journal of clinical pathology, 1995
    Co-Authors: Jan Jacobs, Henk G. Pietersen, Ellen E. Stobberingh, Peter B. Soeters
    Abstract:

    A collection of 518 "Streptococcus milleri" isolates recovered from clinical specimens was identified to the species level according to recently established criteria. Streptococcus anginosus was the most frequently isolated species (59.3%), followed by S constellatus (30.3%) and S intermedius (10.4%). One third (34%) of all isolates were beta-hemolytic. The majority of S anginosus isolates were nonhemolytic, carried Lancefield group F, or were nongroupable. Most of the S constellatus isolates were beta-hemolytic, as well as 16.6% of S intermedius strains. Streptococcus anginosus was recovered more often from the genital and urinary tracts and S constellatus was recovered from the thorax. Streptococcus intermedius was mostly found in the head and neck area, but was also isolated from the abdomen and the skin, bone, and soft tissue. Streptococcus intermedius and nonhemolytic isolates were recovered most often from abscess-related specimens.