Biomedical subjects

R A Whiley

Publications and source records attributed to R A Whiley.

At least 37 records · Page 2Linked to original sources

PubMed1994

Production of specific glycosidase activities by Streptococcus intermedius strain UNS35 grown in the presence of mucin.

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.

Brain Abscess↗

PubMed1993

Evolution of penicillin resistance in Streptococcus pneumoniae; the role of Streptococcus mitis in the formation of a low affinity PBP2B in S. pneumoniae.

Penicillin-resistant strains of Streptococcus pneumoniae possess forms of penicillin-binding proteins (PBPs) that have a low affinity for penicillin compared to those from penicillin-sensitive strains. PBP genes from penicillin-resistant isolates are very variable and have a mosaic structure composed of blocks of nucleotides that are similar to those found in PBP genes from penicillin-sensitive isolates and blocks that differ by up to 21%. These chromosomally encoded mosaic genes have presumably arisen following transformation and homologous recombination with PBP genes from a number of closely related species. This study shows that PBP2B genes from many penicillin-resistant isolates of S. pneumoniae contain blocks of nucleotides originating from Streptococcus mitis. In several instances it would appear that this material alone is sufficient to produce a low affinity PBP2B. In other examples PBP2B genes possess blocks of nucleotides from S. mitis and at least one additional unidentified species. Mosaic structure was also found in the PBP2B genes of penicillin-sensitive isolates of S. mitis or S. pneumoniae. These mosaics did not confer penicillin resistance but nevertheless reveal something of the extent to which localized recombination occurs in these naturally transformable streptococci.

Amino Acid Sequence↗

PubMed1993

Activities of potential therapeutic and prophylactic antibiotics against blood culture isolates of viridans group streptococci from neutropenic patients receiving ciprofloxacin.

All 47 sequential blood culture isolates of viridans group streptococci obtained from febrile neutropenic patients receiving quinolone prophylaxis were susceptible to vancomycin, teicoplanin, and imipenem. Resistance to benzylpenicillin (MIC for 50% of isolates [MIC50], 0.125 microgram/ml) and ceftazidime (MIC50, 4 micrograms/ml) was common. Most isolates were susceptible to amoxicillin, co-amoxiclav (amoxicillin-clavulanic acid at a 2:1 ratio by weight), azlocillin, clarithromycin, and erythromycin, with azithromycin showing comparable activity. The MIC90 of sparfloxacin was 1 microgram/ml; those for ciprofloxacin and ofloxacin were > 16 and 16 micrograms/ml, respectively.

Anti-Bacterial Agents↗

PubMed1993

Species of alpha-hemolytic streptococci possessing a C-polysaccharide phosphorylcholine-containing antigen.

An enzyme-linked immunosorbent assay technique was used to detect and quantify C-polysaccharide-like antigen in strains of alpha-hemolytic streptococci classified into species by following the latest taxonomic recommendations. C-polysaccharide-like antigen is found only in Streptococcus oralis, S. mitis, and S. pneumoniae, which are genetically closely related.

Antigens, Bacterial↗

PubMed1993

Chondroitin sulfate depolymerase and hyaluronidase activities of viridans streptococci determined by a sensitive spectrophotometric assay.

Sensitive spectrophotometric assays for the detection of bacterial chondroitin sulfate depolymerase and hyaluronidase activities were developed by using Stains-all (1-ethyl-2-[3-(1-ethylnaphtho-[1,2-d]thiazolin-2-ylidene)-2- methylpropenyl]naphtho-[1,2-d]thiazolium bromide). Stains-all interacts with hyaluronic acid to produce a shift in the absorption spectrum with a distinct absorption peak between 620 and 660 nm, while chondroitin sulfate interacts to form a distinct shoulder between 440 and 500 nm. Assays measure undegraded substrate. A collection of 110 strains of viridans streptococci, including representatives of all the currently recognized species, was studied. Streptococcus intermedius and S. constellatus degraded hyaluronic acid, while only strains of S. intermedius, primarily isolated from brain and liver abscesses, produced chondroitin sulfate depolymerase. S. intermedius, of all the viridans streptococci, produces the widest range of glycoprotein- and glycosoaminoglycan-degrading enzymes, which may contribute to the virulence of this species.

Chondroitinases and Chondroitin Lyases↗

PubMed1992

A numerical taxonomic study of the "Streptococcus milleri" group based upon conventional phenotypic tests and pyrolysis mass spectrometry.

Clinical strains presumptively identified as Streptococcus milleri (60), and blind coded collection strains (21) were characterised in conventional tests and pyrolysis mass spectrometry. Comparison of the clusters found by these two approaches revealed five clearly distinct centres of variation. Three corresponded to the DNA homology groups suggested by Whiley and Hardie (1989) as representing the species S. anginosus, S. intermedius and S. constellatus; a fourth comprised three Lancefield group C beta-haemolytic strains; the fifth may represent a biotype of S. anginosus. The characteristics of the latter group are described.

Cluster Analysis↗

PubMed1992

Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus (the Streptococcus milleri group): association with different body sites and clinical infections.

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.

Central Nervous System Diseases↗

PubMed1991

Emended descriptions and recognition of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus as distinct species.

Strains currently classified as Streptococcus anginosus include strains previously identified as Streptococcus constellatus (Prevot 1924) Holdeman and Moore 1974, Streptococcus intermedius (Prevot 1925), and "Streptococcus milleri" (Guthof 1956) because these specific epithets were argued to be later synonyms of Streptococcus anginosus (Andrewes and Horder 1906) Smith and Sherman 1938 by Coykendall et al. (Int. J. Syst. Bacteriol. 37:222-228, 1987). However, recent data from DNA-DNA hybridization experiments, whole-cell-derived polypeptide patterns determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and data from phenotypic testing have demonstrated that Streptococcus anginosus strains represent three readily identifiable taxa to which the previously assigned type strains of Streptococcus constellatus (strain NCDO 2226 [= ATCC 27823], Streptococcus intermedius (strain NCDO 2227 [= ATCC 27335], and Streptococcus anginosus (strain NCTC 10713 [= ATCC 33397] have been shown to belong. Therefore, we propose recognition of Streptococcus constellatus (emend.) (type strain NCDO 2226 [= ATCC 27823]), Streptococcus intermedius (emend.) (type strain NCDO 2227 [= ATCC 27335]), and Streptococcus anginosus (emend.) (type strain NCTC 10713 [= ATCC 33397]) as distinct species and propose an emended description of each of these taxa.

Base Composition↗

PubMed1991

Streptococcus crista sp. nov., a viridans streptococcus with tufted fibrils, isolated from the human oral cavity and throat.

We studied strains of an unusual streptococcus that superficially resembles Streptococcus sanguis but has fibrils that are arranged in lateral tufts. These strains were originally isolated from human throats and oral cavities and have been referred to previously as "Streptococcus sanguis I," the "CR group," and the "tufted-fibril group." Until now, insufficient phenotypic data have been available to allow reliable differentiation of these strains from other viridans streptococcal species, particularly the species in the S. sanguis group. Recently, workers have proposed a scheme of phenetic tests that is based on 4-methylumbelliferyl-linked substrates and conventional biochemical tests and allows the tufted-fibril group to be differentiated; these organisms differ from other viridans species in being able to hydrolyze arginine but not esculin and in producing alpha-L-fucosidase but not beta-glucosidase or alkaline phosphatase. These data, together with the results of our DNA-DNA hybridization experiments and the unusual ultrastructure of the tufted-fibril strains as determined by electron microscopy, demonstrate that these organisms represent a new species, for which the name Streptococcus crista is proposed. The DNA base composition is 42.6 to 43.2 mol% G + C. The type strain is strain CR311 (= NCTC 12479).

DNA, Bacterial↗

PubMed1991

A scheme for the identification of viridans streptococci.

A collection of strains representing all the currently recognised species of oral or viridans streptococci (Streptococcus sanguis, S. parasanguis, S. gordonii, S. oralis, S. mitis, S. salivarius, S. vestibularis, S. anginosus, S. constellatus, s. intermedius, S. mutans and S. sobrinus) were tested for the production of a range of glycosidase activities with 4-methylumbelliferyl-linked fluorogenic substrates, and for reactions in a range of conventional fermentation and hydrolytic tests. The resulting biochemical scheme, consisting of 14 tests, enabled the differentiation of all these species and distinguished three biotypes within S. sanguis. The scheme reported here represents an improvement over currently available schemes for the identification of viridans streptococci.

Culture Media↗

PubMed1991

Conservation of the gene encoding streptococcal antigen I/II in oral streptococci.

The spaP gene of Streptococcus mutans serotype c encodes a major cell surface protein, streptococcal antigen (SA) I/II, with an Mr of 185,000, that is thought to be involved in bacterial adhesion to teeth. Proteins with significant amino acid sequence homology to SA I/II have also been found in S. sobrinus and S. sanguis. The objectives of this study were to investigate the conservation of the spaP gene in the mutans groups of streptococci and to determine whether homologous genes were present in other species of alpha-hemolytic streptococci. DNA extracted from representative strains of 19 streptococcal species was examined by Southern hybridization and partial DNA sequence analysis. A series of five overlapping DNA probes from the spaP gene were amplified by the polymerase chain reaction and used in the Southern hybridizations. The entire gene was found to be well conserved in all strains of S. mutans serotypes c, e, and f investigated. A probe from the 3' region of the gene, which encodes residues 857 to 1207 of the SA I/II protein, hybridized with DNA from a number of mutans streptococci, as well as with DNA from nonmutans alpha-hemolytic streptococci. Conservation within this region was further demonstrated by sequencing gene fragments of two strains of S. intermedius and S. oralis. The results show that some regions of the spaP gene are highly conserved not only in the mutans group of streptococci but also in other nonmutans alpha-hemolytic streptococci. This suggests that a family of cell surface proteins which, by analogy with the 185,000-Mr SA I/II of S. mutans, could be involved in bacterial adhesion might exist.

Amino Acid Sequence↗

PubMed1991

A simple biochemical scheme for the differentiation of Streptococcus mutans and Streptococcus sobrinus.

A collection of wild-type and reference strains of Streptococcus mutans and Streptococcus sobrinus was compared using a set of fermentation and enzymic tests in order to establish a simple scheme for the differentiation of these two species isolated from selective media. Tests for the production of acid from N-acetylglucosamine, arbutin and melibiose, and the presence of alpha-galactosidase and alpha-glucosidase activities were useful in differentiating these species. Strains of Streptococcus mutans unable to ferment melibiose were also frequently unable to ferment other sugars; a consideration of the genetic control and organization of the genes involved in melibiose metabolism indicates that certain of the conventional characterization tests are not measurements of independent biochemical capabilities.

Adolescent↗

PubMed1990

Streptococcus parasanguis sp. nov., an atypical viridans Streptococcus from human clinical specimens.

Molecular taxonomic studies were performed on ten strains of an unusual 'viridans streptococcus' that were originally isolated from human throats, blood and urine. On the basis of DNA-DNA hybridization studies the strains formed a single homology group distinct from all recognized species of oral and viridans streptococci. 16S ribosomal RNA reverse transcriptase sequence studies confirmed the genealogical distinctiveness of the human strains. The results of the present study clearly demonstrate that the human strains represent a new species of the viridans group for which the name Streptococcus parasanguis sp. nov. is proposed. The type strain is ATCC 15912.

Base Sequence↗

PubMed1990

Amylase-binding as a discriminator among oral streptococci.

The ability of 51 strains, belonging to Streptococcus sanguis, 'S. mitior', S. oralis and related groups, to bind salivary amylase was studied. Most strains were grouped according to their DNA-relatedness and then compared using 14 phenotypic tests. S. mitis, 'S. mitior' and three relatively new groups of strains ('CR', 'MGH' and 'Tufted mitior') bound salivary amylase, while strains of S. sanguis and S. oralis did not. The ability of strains to bind amylase or not was remarkably consistent within groups and the test proved to be reproducible, rapid and easy to perform. Combination of the amylase-binding test with 6 other conventional physiological tests allowed the construction of a dichotomous identification key which correctly identified 95% of strains for which genetic data was available. These findings suggest that the ability of organisms to bind salivary amylase could become a key test in identification schemes for certain oral streptococci.

DNA, Bacterial↗

PubMed1990

Proteolytic activity of oral streptococci.

Streptococcus mutans and Streptococcus sobrinus were the least proteolytic of 8 species of oral streptococci while Streptococcus oralis and Streptococcus sanguis were the most proteolytic. Degradation of FITC-BSA was significantly correlated with the hydrolysis of synthetic endopeptidase substrates. As S. oralis strains proliferate in dental plaque in the absence of dietary food their success, in vivo, might be due partially to their greater proteolytic activity compared to other oral streptococci.

Caseins↗

PubMed1990

Sialidase activity of the "Streptococcus milleri group" and other viridans group streptococci.

Viridans group streptococci were examined for the production of sialidase (neuraminidase) activity, using the fluorescent substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid in a simple and rapid (15-min) assay. Sialidase was produced by all strains of Streptococcus oralis and S. intermedius and by a majority of S. mitis strains. S. mutans, S. sobrinus, S. gordonii, S. sanguis, S. vestibularis, S. salivarius, S. anginosus, S. constellatus, "S. parasanguis," and the "tufted fibril group" were uniformly negative. Sialidase production may be a useful characteristic to assist in the identification of viridans group streptococci.

Humans↗

PubMed1990

Phenotypic differentiation of Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus strains within the "Streptococcus milleri group".

A biochemical scheme was developed by which strains of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus can reliably be distinguished from within the "Streptococcus milleri group." Strains identified as S. intermedius were differentiated by the ability to produce detectable levels of alpha-glucosidase, beta-galactosidase, beta-D-fucosidase, beta-N-acetylgalactosaminidase, beta-N-acetylglucosaminidase, and sialidase with 4-methylumbelliferyl-linked fluorogenic substrates in microdilution trays after 3 h of incubation at 37 degrees C, together with the production of hyaluronidase. Strains of S. constellatus and S. anginosus were differentiated by the production of alpha-glucosidase and hyaluronidase by the former and the production of beta-glucosidase by the latter. The majority of strains of the S. milleri group obtained from dental plaque were identified as S. intermedius, as were most strains isolated from abscesses of the brain and liver. Strains of S. constellatus and S. anginosus were from a wider variety of infections, both oral and nonoral, than were strains of S. intermedius, with the majority of strains from urogenital infections being identified as S. anginosus.

Dental Plaque↗

PubMed1989

DNA-DNA hybridization studies and phenotypic characteristics of strains within the 'Streptococcus milleri group'.

Twenty-five strains resembling 'Streptococcus milleri' were compared by DNA-DNA hybridization, by whole-cell-derived polypeptide patterns on SDS-PAGE, and by biochemical tests. Four homology groups were revealed by DNA-DNA hybridization. DNA homology groups 1, 2 and 3 were closely related and contained the type strains NCDO 2226 (Streptococcus constellatus), NCDO 2227 (Streptococcus intermedius) and NCTC 10713 (Streptococcus anginosus), respectively. DNA homology group 4 consisted of four strains received as variants of Streptococcus intermedius which were found not to be closely related to strains in groups 1-3. The data from SDS-PAGE polypeptide patterns and biochemical tests supported the recognition of three centres of variation within the 'Streptococcus milleri group' corresponding to DNA homology groups 1-3 and indicated that strains of DNA homology group 4 are members of an as yet undescribed species within the viridans streptococci.

Bacterial Proteins↗