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D Beighton

Publications and source records attributed to D Beighton.

At least 55 records · Page 3Linked to original sources
PubMed1999

PCR-Based methods for genotyping viridans group streptococci.

Standard repetitive extragenic palindromic (REP)-PCR, enterobacterial repetitive intergenic consensus-PCR, and Salmonella enteritidis repetitive element-PCR methods for bacterial strain typing were performed with DNA extracted by boiling members of each of the currently recognized species of human viridans group streptococci. Each of the methods was reproducible. The unique isolates (n = 72) from 15 species of viridans group streptococci were readily distinguishable, with no two isolates showing greater than 90% per cent similarity. The majority of strains exhibited much less than 90% similarity. Isolates identical by REP-PCR were also identical by the other two methods. These PCR-based typing methods, although they do not permit determination of the species of the isolates, are simple to perform and are suitable for clinical and ecological investigations of viridans group streptococci.

Genotype↗
PubMed1999

Growth of Viridans streptococci on human serum alpha1-acid glycoprotein.

Viridans streptococci have emerged as major opportunistic pathogens. We suggest that for these bacteria to proliferate in vivo and cause disease, they must utilize host tissue components. We have therefore examined the ability of all recognized species of viridans streptococci to liberate and utilize the constituent sugars of the glycans of the extensively sialylated human serum alpha1-acid glycoprotein (AGP) as the sole source of carbohydrate to support in vitro growth. Analysis of residual glycans following bacterial growth was performed by high-pH anion exchange chromatography with pulsed amperometric detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Only those species which produced sialidase-namely, Streptococcus oralis, S. intermedius, and S. defectivus--grew on AGP. The extent of degradation of glycans was dependent on the particular glycosidases produced by the bacteria. S. defectivus produced only a sialidase which released the terminal N-acetylneuraminic acid residues of the glycans, and the liberated sugar was utilized. S. intermedius also produced beta-galactosidase and beta-N-acetylglucosaminidase, which removed galactose and N-acetylglucosamine from desialylated glycans, all of which again were utilized by the organism. S. oralis produced beta-galactosidase, beta-N-acetylglucosaminidase, and alpha-fucosidase and novel alpha- and beta-mannosidases which were apparent only from the analysis of the residual sugars of AGP. S. oralis cleaved all the sugars from AGP except for 22% of the N-acetylglucosamine. The residual N-acetylglucosamine residues remaining were those linked to the asparagine of the peptide backbone. All the monosaccharides released by S. oralis from AGP, with the exception of fucose, were utilized. Sialidase production may be a key factor for growth of these species of viridans streptococci on glycoproteins in vivo, since they are commonly associated with extra-oral diseases, with S. oralis emerging as an important pathogen.

Acetylglucosaminidase↗
PubMed1999

The predominant Actinomyces spp. isolated from infected dentin of active root caries lesions.

Actinomyces are Gram-positive pleomorphic rods (GPPR) which form a large proportion of the oral microflora of all mammals. They have been implicated in root caries, although their role in dental caries initiation and progression is not well-understood. Many studies have focused on Actinomyces naeslundii, but few reports have documented other members of the GPPR. Therefore, we investigated the GPPRs isolated from infected dentin of active root caries lesions (n = 9) to determine which species were the most frequently isolated. The GPPR were isolated under both aerobic and anaerobic conditions and identified by biochemical and physiological tests to the species level according to the new taxonomy. Of 654 GPPR isolates investigated, 607 were identified as belonging to the genus Actinomyces. Of these, 242 were identified as A. israelii, 225 as A. gerencseriae, 109 as A. naeslundii, 15 as A. odontolyticus, and 13 as A. georgiae. Individual strains of A. israelii (n = 56) and A. gerencseriae (n = 46) were also investigated at the DNA level by means of Repetitive Extragenic Palindromic polymerase chain-reactions (REP-PCR) for the study of clonal diversity. Although only a small number of isolates was investigated, REP-PCR showed that the genotypes of both A. gerencseriae and A. israelii populations were heterogeneous within individual root caries lesions. A. gerencseriae and A. israelii strains from the same lesions did not share the same REP-PCR patterns, showing the robustness of the identification scheme. A significantly greater proportion of A. gerencseriae was isolated from the aerobic plates (p < 0.05), while the proportion of A. israelii was significantly (p < 0.05) greater from anaerobic plates. The role of individual Actinomyces spp. in the root caries process remains unclear, since various populations of GPPRs were isolated from individual active root caries lesions.

Actinomyces↗
PubMed1998

Evidence for mannosidase activities in Streptococcus oralis when grown on glycoproteins as carbohydrate source.

Streptococcus oralis when cultured using ribonuclease B as the sole source of carbohydrate, selectively uses the sugars of the Man5 glycoform as shown by HPAEC and MALDI-TOF mass spectrometric analyses. The organism is able to do this by producing novel alpha-(1-->3), alpha-(1-->6) and beta-(1-->4) mannosidase activities and these act in a concerted manner in what appears as a single-step process. The selective utilisation of Man5 is explained by the absence of an alpha-(1-->2) mannosidase which is required to initiate breakdown of the glycan chains present in the other glycoforms which are components of the glycoprotein.

Carbohydrate Conformation↗
PubMed1998

Oral health of children undergoing allogeneic bone marrow transplantation.

The objective of this study was to investigate changes in the oral health of children undergoing allogeneic bone marrow transplantation. The study group comprised 23 children undergoing allogeneic bone marrow transplantation and their matched controls. The study group comprised 23 children undergoing allogeneic bone marrow transplantation and their matched controls. Measurements were taken of the mean decayed, missing and filled surfaces and the mean decayed, missing and filled teeth in both deciduous and permanent dentition at baseline, the mean bacterial plaque and gingival inflammation indices and mucositis at specific event-related times during the transplantation period, were measured. The number of decayed, missing and filled surfaces in deciduous teeth was significantly greater in the transplant children than the matched controls (P < 0.05) at baseline. There was a significant increase in both the mean bacterial plaque score for the deciduous teeth (P < 0.003) and the permanent teeth (P < 0.001) and the mean gingival inflammation score for the deciduous (P < 0.001) and the permanent teeth (P < 0.001), at 7 days post-transplantation. At 4 months post-transplantation the plaque and gingival inflammation score had returned to baseline levels. There were significantly increased mean bacterial plaque and gingival inflammation scores during the period of intense immunosuppression following allogeneic bone marrow transplantation.

Bone Marrow Transplantation↗
PubMed1998

Identification and antibiotic susceptibility of Nocardia farcinica and N. nova in the UK.

Nocardia asteroides has long been recognised as a heterogeneous group of organisms. The description and identification of two new subgroups, N. farcinica and N. nova, in other countries encouraged us to re-examine a collection of N. asteroides isolates from the UK. Of 73 clinical isolates identified as N. asteroides from different parts of England and Wales during 1991-1993, and now subjected to further differentiation tests by the Mycobacterial/Nocardial Reference Laboratory, 15 (20.5%) were identified as N. farcinica based on three out of four characteristics: growth property, acetamide production, rhamnose assimilation and a distinct antibiogram. No isolates were identified as N. nova. A revised identification and susceptibility system has significant clinical and taxonomic implications. Its introduction will improve speciation, identify antibiotic resistance and influence the choice of safer alternative therapy for patients infected with Nocardia spp. in the UK.

Bacterial Typing Techniques↗
PubMed1998

Current classification of the oral streptococci.

The classification of the oral streptococci has long remained a difficult area of streptococcal taxonomy. This article reviews the current classification of these bacteria into four species groups, and each group is described in detail. The often confusing changes that have taken place in the classification, identification and nomenclature of the member species are reviewed against a historical background of gradually improving techniques and approaches, leading towards a natural classification based primarily on genotypic evidence. Identification schemes currently in use employing biochemical tests are also reviewed, together with alternative molecular approaches.

Bacterial Typing Techniques↗
PubMed1998

The isolation of Actinomyces naeslundii from sound root surfaces and root carious lesions.

The isolation of Actinomyces naeslundii from sound, exposed root surfaces (n = 56) and soft and leathery root carious lesions (n = 71) was investigated. Root carious lesions were sampled after the removal of overlying plaque. Supragingival plaque or carious dentine was sampled using a sterile excavator, the samples were disaggregated and cultured on both selective and non-selective media. A. naeslundii isolates were identified to the genospecies using specific antisera. Significantly greater numbers and proportions of A. naeslundii genospecies 2 than A. naeslundii genospecies 1 were isolated from all sites sampled. There was no significant difference between the numbers and proportions of the two genospecies isolated from leathery and soft lesions. The relationship between the presence of A. naeslundii genospecies and aciduric and acidogenic organisms was investigated. Those sound exposed root surfaces from which A. naeslundii genospecies 1 and/or 2 were isolated yielded significantly lower numbers of lactobacilli and yeasts than the surfaces from which A. naeslundii were not isolated. This difference was also found in leathery lesions but not soft root carious lesions. The microflora of soft root carious lesions was found to comprise primarily gram-positive pleomorphic rods which formed 70+/-7.8% of the flora, while in plaque from exposed root surfaces and in infected dentine from leathery lesions the gram-positive pleomorphic rods represented only 35% of the flora.

Actinomyces↗
PubMed1997

Endopeptidase activities of selected Porphyromonas spp., Prevotella spp. and Fusobacterium spp. of oral and non-oral origin.

The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fusobacterium warrants further investigation.

Alanine↗
PubMed1997

Changes in the oral streptococcal flora of children undergoing allogeneic bone marrow transplantation.

The changes in the oral streptococcal flora of twenty children undergoing allogeneic bone marrow transplant are described. Saliva was collected from each child on four separate occasions: (i) before the conditioning regimen; (ii) 7 days post-transplantation; (iii) when the neutrophil count had risen above 0.5 x 10(9)/l; (iv) 119 days post-transplantation. Indices for dental caries, plaque, gingivitis, herpetic stomatitis and mucositis were also recorded. There was a significant decrease in the total aerobic (P<0.001) and anaerobic counts (P<0.0002) between baseline and 7 days post-transplantation. The proportion of the 'Streptococcus oralis group' (Streptococcus mitis and S. oralis) increased significantly from baseline 12.1% to 48.4% at 7 days post-transplantation (P<0.003). The plaque and gingivitis indices increased significantly from baseline to 7 days post-transplantation (P<0.001). Twenty percent of the children had either positive blood cultures or Hickman line cultures for the 'S. oralis group', and it is possible that the inflamed gingival tissues are a further site of entry for these streptococci. There were no differences in the total anaerobic counts or the proportion of the 'S. oralis group' between baseline and the end of the study in the transplant children, or between the transplant and control children.

Bone Marrow Transplantation↗