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At least 613 records · Page 34Linked to original sources
PubMed2000

Implant-supported overdenture therapy: a 3- to 8-year prospective study.

Inflammatory changes in periimplant soft tissues and loss of alveolar bone can develop as in periodontal diseases. This clinical phenomena has been described as periimplantitis. Microorganisms such as Gram-negative anaerobic rods, spirochetes, and bacteroides that are seen in subgingival flora in periodontitis have also been found in sulcular microflora in periimplantitis. The purpose of this study was to evaluate periimplant tissue changes in totally edentulous patients who had implant-supported overdentures for 3 to 8 years (5-5.5 years) clinically from both a subjective and an objective point of view. The clinical parameters used in this study can be helpful in the evaluation of periimplant tissue health.

Dental Implantation, Endosseous↗
PubMed1978

Biochemical effects of and bacteriological response to sugar substitutes in the oral environment.

The problems of the biochemical effects of sugar substitutes and bacteriologic response to such substitutes in the oral cavity may fill a whole book. Therefore, considerable restrictions in the presentation are necessary. Noncaloric sweeteners and additives are not utilized by the oral microorganisms for metabolism and acid production and are therefore of minor interest in this connection. This presentation mainly concerns sugar alcohols and related substances, primarily sorbitol, xylitol and Lycasin. Monosaccharides and other saccharides are not dealt with in this presentation even if some of them are of considerable interest; for example fructose, invert sugar and others. Sugar alcohols are used as substitutes because they cannot be utilized by the vast majority of oral organisms for fermentation, acid production or production of polysaccharides. There is a risk that the oral flora will adapt to these products and that such a substitute, which is originally nonacidogenic, may subsequently be utilized for fermentation and may even induce dental caries.

Acids↗
PubMed1972

Saliva-induced aggregation of oral streptococci.

Cells of several species of oral microorganisms have been shown, in earlier studies, to be aggregated by saliva. In the present study some of the basic properties of the aggregation system are examined. The observation is made that the saliva-induced aggregates of Streptococcus sanguis and S. mitis can be dissociated to stable particles which consist of about 100 cells and have a median diameter of about 4.5 mum. It is proposed that these are subunits, or core aggregates, of the large primary aggregates. Counts of the core aggregates can be taken as a precise and accurate measure of aggregation. Experiments based on this procedure show that the aggregation of S. sanguis is maximal at 10 C and at 1 meq of Ca(2+) ions per liter and is not affected by a change in pH between 3.9 and 8.7 or by a change in the phase of growth of the microorganisms. Core aggregates diminish in number with prolonged incubation, suggesting that the aggregating factors break down with time. Formalinized cells yield stable aggregates. However, with Formalinized cell aggregation is maximal between 20 and 30 C and proceeds in the absence of calcium ions. Evidence is presented that whole saliva contains separate aggregating factors for S. sanguis and S. mitis. The factors differ in their affinity for intact cells and for hydroxyapatite and differ in their stability to dialysis. These findings suggest that many different aggregating factors exist in saliva, each of which may be capable of interacting with cells of one or several bacterial species.

Adsorption↗
PubMed2004

The role of oral microbial colonization in ventilator-associated pneumonia.

The present article reviews the association between microbial colonization of the oral cavity and the lungs in critically ill patients that develop ventilator-associated pneumonia (VAP) in the intensive care unit (ICU) setting. The risk factors and microorganisms associated with VAP are presented. The role of oral colonization of VAP-associated pathogens (VAP-AP) in the development of VAP is examined. We explore the potential factors involved in oral colonization of VAP-AP, which are atypical bacteria for the oral cavity. Strategies for the prevention or moderation of oral colonization of VAP-AP have had limited success. We need a deeper understanding of the pathophysiology of VAP in order to reduce the morbidity, mortality, and cost from this common complication in ICU medicine and surgery.

Bacterial Physiological Phenomena↗
PubMedDate not supplied

[Oral cavity microbial coenobia in healthy children and children with chronic recurrent aphthous stomatitis].

Peculiarities of quantitative and qualitative composition of microbiocenosis of the oral cavity in healthy children and children with chronic aphthous recurrent stomatitis have been studied. Strains of microorganisms (n = 259) have been isolated and identified. The results obtained showed that the studied biotope is characterised by a wide spectrum of isolated microflora. The growth of microorganism association is observed in all the studied samples. The analysis of genus and species composition of microbiocenosis of the mucous membrane indicated that streptococci, neiserii, corynebacteria, enterococci, lactobacilli, epidermal staphylococci and candidas were distinguished as to isolation frequency among the isolated strains. These bacteria were isolated from oral cavity of healthy and sick children, but their quantity in 1 mm2 of sick children mucosa prevailed, except for Streptococcus salivarius, S. mitis and Lactobacillus sp.: their quantity was far less. Golden staphylococci, escherichia, klebsiella, clostridia, hemophilic rods and campylobacteria were isolated from sick children only.

Adolescent↗
PubMed1983

Cysteine toxicity for oral streptococci and effect of branched-chain amino acids.

Cysteine was bactericidal to strains of Streptococcus mutans and S. salivarius in concentrations that were nontoxic to S. sanguis, S. milleri, or S. mitior when these microorganisms were incubated in a saliva protein-based synthetic medium. Cysteine toxicity for S. mutans also occurred after incubation in synthetic base medium supplemented with amino acids as the nitrogen source for growth. The bactericidal effect of cysteine for S. mutans or S. salivarius in the saliva protein medium was influenced by the cysteine oxidative activity associated with the saliva protein fraction. Valine alone or in combination with leucine or isoleucine was effective in overcoming cysteine toxicity for susceptible strains of S. mutans or S. salivarius. Cysteine toxicity for these oral streptococci may be due to cysteine inhibition of an enzymatic step in the valine-leucine biosynthetic pathway.

Amino Acids, Branched-Chain↗
PubMed1985

Microbe-induced lymphocyte blastogenesis enhancement after preculture.

The in vitro blastogenic response of human peripheral blood mononuclear cells to Fusobacterium nucleatum and other oral microorganisms was enhanced if the peripheral blood mononuclear cells were cultured for 24 h at 37 degrees C prior to the addition of stimulant. The enhancement which occurred at optimal and supraoptimal concentrations of F. nucleatum (10 to 100 micrograms/ml) was detected after a preculture period of as little as 2 h. The blastogenic response was a result of T-cell proliferation, and enhancement occurred independently of monocytes. Suppressor activity was induced by culturing fresh lymphocytes for 24 h in the presence of supraoptimal concentrations of F. nucleatum. The enhancement phenomenon occurred independently of the prostaglandin effects on lymphocyte blastogenesis and was not abrogated by treatment with indomethacin.

Adolescent↗
PubMed2004

Photodynamic therapy: a new antimicrobial approach to infectious disease?

Photodynamic therapy (PDT) employs a non-toxic dye, termed a photosensitizer (PS), and low intensity visible light which, in the presence of oxygen, combine to produce cytotoxic species. PDT has the advantage of dual selectivity, in that the PS can be targeted to its destination cell or tissue and, in addition, the illumination can be spatially directed to the lesion. PDT has previously been used to kill pathogenic microorganisms in vitro, but its use to treat infections in animal models or patients has not, as yet, been much developed. It is known that Gram-(-) bacteria are resistant to PDT with many commonly used PS that will readily lead to phototoxicity in Gram-(+) species, and that PS bearing a cationic charge or the use of agents that increase the permeability of the outer membrane will increase the efficacy of killing Gram-(-) organisms. All the available evidence suggests that multi-antibiotic resistant strains are as easily killed by PDT as naive strains, and that bacteria will not readily develop resistance to PDT. Treatment of localized infections with PDT requires selectivity of the PS for microbes over host cells, delivery of the PS into the infected area and the ability to effectively illuminate the lesion. Recently, there have been reports of PDT used to treat infections in selected animal models and some clinical trials: mainly for viral lesions, but also for acne, gastric infection by Helicobacter pylori and brain abcesses. Possible future clinical applications include infections in wounds and burns, rapidly spreading and intractable soft-tissue infections and abscesses, infections in body cavities such as the mouth, ear, nasal sinus, bladder and stomach, and surface infections of the cornea and skin.

Animals↗
PubMed1990

Liposomes containing anti-idiotypic antibodies: an oral vaccine to induce protective secretory immune responses specific for pathogens of mucosal surfaces.

By using a gnotobiotic rat model system to study the induction of protective immune responses by anti-idiotype (anti-id) vaccines specific for antibodies directed at the cariogenic microorganism Streptococcus mutans, it was shown that administration of such an anti-id vaccine provided partial protection against dental caries after challenge with virulent microorganisms. Protective effects were first demonstrated by direct parenteral administration of the anti-id vaccine into salivary gland regions, as determined by reductions in microbial colonization and caries scores. Subsequently, the anti-id was incorporated into liposomes and administered by gastric intubation. Immunization by this regimen also resulted in a significant reduction in caries as well as S. mutans colonization of the oral cavity, with concomitant increases in salivary immunoglobulin A anti-S. mutans antibodies. These data provide evidence that anti-id vaccines specifically targeted at the secretory immune system can induce protective immune responses to pathogens of mucosal surfaces.

Administration, Oral↗
PubMed1999

Evidence for an oral-faecal transmission of Helicobacter pylori infection in an experimental murine model.

An experimental murine model was used to evaluate the possible animal-to-animal transmission of Helicobacter pylori and the mechanism involved. Twenty-four Balb/C mice were infected with H. pylori type I strain culture and kept with 24 noninoculated mice to evaluate the possible transmission of the microorganism. Twelve inoculated mice were housed with 12 noninoculated mice in a grated cage (supporting an oral-oral transmission); the remaining inoculated and noninoculated mice were housed in another cage without grating on the floor (supporting a faecal-oral transmission). The bacterial colonization was assessed by culture and immunohistochemistry. The systemic antibody response to H. pylori and the histopathological changes were evaluated; controls were examined at 2, 4, 8, 12 weeks after the start of the experiment. Faecal samples were also collected from each mouse on the day before sacrifice, to assess the presence of H. pylori by culture and by immunohistochemistry. In the gastric mucosa of inoculated mice, histopathological changes were recorded at each control time and H. pylori was detected both by immunohistochemistry and by a systemic antibody response; the microorganism was also cultured at 2, 4, 8 weeks postinoculation. H. pylori was detected in noninoculated mice, housed in the cage without grating, using an immunoperoxidase technique at 2, 4, 8 weeks after starting the experiment, and these positive values were supported by histopathological changes, and, in one case, at 8 weeks, also by the serum immune response. No colonies of H. pylori were detected by culturing faecal samples from either noninoculated or inoculated mice. The results obtained in this study seem to support an oral-faecal route as the mode of transmission of H. pylori infection in this animal model.

Animals↗
PubMed1976

Possible mechanisms for the cariostatic effect of xylitol.

Xylitol appears to be the only known cariostatic natural carbohydrate which meets most of the desiderata for a sweetener in the human diet. Possible mechanisms for this cariostatic action can be derived from a consideration of the factors which may be operating at a molecular and microbiological level. These include: a) Molecular size and e.g. the short, open-chain structure and absence of reducing groups b) Absence or relative lack in most oral microorganisms of xylitol-binding factors in dental plaque c) Lack of bacterial genes coding for xylitol-utilizing enzymes or of inducible or de-repressible genes for this purpose d) Inhibition of enzymes involved in cariogenesis (competitive in case of some isomerases) e) Enzyme specificity requirements f) Higher osmotic pressure exerted by xylitol as compared to hexoses and disaccharides g) Ability of xylitol to produce a favourable electrolyte concentration in the saliva without lowering plaque pH h) Ability of xylitol to increase the secretion and activity of salivary lactoperoxidase and certain other (muco) proteins. Xylitol may enhance the adsorption of glycoproteins on the tooth surfaces and strengthen the acquired pellicle.

Bacteria↗
PubMed1986

Calcium-dependent salivary agglutinin with reactivity to various oral bacterial species.

Human parotid agglutinins from three individuals were isolated by adsorption to and desorption from strains of Streptococcus mutans belonging to serotypes a, b, c, d, and e and strains of Lactobacillus casei, Actinomyces viscosus, and Streptococcus sanguis. The desorption was achieved by suspending centrifuged saliva-coated microorganisms in 10 mM phosphate buffer (pH 6.8) containing 0.154 M sodium chloride. After another centrifugation, agglutinin activity was recovered in the supernatants. The L. casei strain was not agglutinated by any of the agglutinin extracts or by saliva, but all the other strains were agglutinated to a variable extent. However, all strains, including the nonagglutinating L. casei strain, adsorbed and desorbed agglutinins active for other strains. The agglutinin extracts from S. mutans serotype c, S. sanguis, and A. viscosus were purified and characterized by electrophoretic and immunological techniques. The purified preparations were positively stained for protein and carbohydrate, and the molecular weights were estimated to be 440,000. All agglutinin extracts needed calcium in the range of 0.1 to 0.5 mM to be active, and for a single strain, all agglutinins gave the same degree of agglutination, indicating that the isolated agglutinins may be of the same molecular species, a hypothesis that was also confirmed by the preliminary characterization of the purified agglutinins. This type of agglutinin, which seems to exert its activity among various bacterial species, could be important in mediating bacterial coaggregation and thus may add to the effect of specific agglutinins in the clearance of bacteria from the human mouth.

Actinomyces↗
PubMed1989

Intra-oral colonization of macaque monkeys by Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans was acquired by captive Macaca fascicularis 3 to 6 months after birth, and all monkeys aged over 6 months harbored detectable levels. This microorganism was most frequently isolated from the gingival plaque of the incisor (and other) teeth compared with other oral sites. Strains were leukotoxic by bioassay and Western blot analysis. Antibodies in macaque serum contained neutralized the leukotoxin of a human A. actinomycetemcomitans strain. High titres of maternal neutralizing anti-leukotoxin antibodies were detected in neonates; the titre then fell rapidly so that by 6 months the antibody titer was zero. Antileukotoxin antibody production was detected after 6 months of age, rapidly reaching a high level within 2 years after birth. The presence of leukotoxic strains of A. actinomycetemcomitans in the gingival region did not appear to be correlated with an increase in susceptibility to periodontal disease.

Actinobacillus↗
PubMed2000

Adsorption of oral bacteria to porous type calcium carbonate.

The purpose of this study was to investigate the adsorption of [3H]-thymidine labeled oral microorganisms to porous type calcium carbonate (PCC) beads in a buffer containing human parotid saliva and to PCC combined chewing gum sheets. Adsorption rates of Streptococcus sobrinus B13 and 6715, Streptococcus mutans MT8148R and Actinomyces naeslundii T14V with PCC were significantly higher than those with calcium carbonate (CC) beads (p < 0.01). Adsorption rates of S. sobrinus, S. mutans and A. naeslundii with PCC combined chewing gum were significantly higher than those with CC combined chewing gum (p < 0.01). The present results suggested that the chewing gum containing PCC may be able to exclude oral bacteria, including cariogenic and periodontopathic bacteria, for prevention of dental caries and periodontal disease.

Actinomyces↗
PubMed2002

[Candida colonization on the surface of orthodontic brackets and the adhesion of these strains to buccal epithelial cells].

Many types and numbers of microorganisms may be colonized in the oral cavity. Candida albicans is the most frequently isolated fungal species which colonizes oral mucosal cells Denture prostheses play an important role by increasing the risk of colonization. In this study, Candida colonization and adhesion rates have been investigated among 60 orthodontic bracket users (mean age: 17.8 years), and 15 (25%) of them were found to be colonized by Candida species (13 C. albicans, 1 C. kefyr, 1 C. lusitaniae). Fourteen of 15 subjects (93.3%) were between 16-18 years old. All the isolates were exposed with buccal epithelial cells in-vitro, and the adhesion rate was found to be 12%. The adhesion activity was detected only in C. albicans strains.

Adolescent↗
PubMed2026

Oral cavity as a reservoir of respiratory pathogens: microbial dynamics in patients receiving mechanical ventilation.

OBJECTIVE: To investigate the prevalence, co-occurrence, and temporal dynamics of Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae, and Pseudomonas aeruginosa in oral and tracheal samples from critically ill patients receiving mechanical ventilation. METHODS: This observational analytical study included 21 adult patients receiving mechanical ventilation who were admitted to an intensive care unit. Oral and tracheal samples were collected within the first 24 h after intubation (Day 0) and again after 48 h (Day 2). Bacterial genomic deoxyribonucleic acid was extracted and analyzed using quantitative realtime polymerase chain reaction. Microbial detection was evaluated qualitatively based on the presence or absence of each microorganism and quantitatively using relative bacterial load analysis. Statistical analyses assessed correlations between oral and tracheal colonization patterns and temporal changes in bacterial load. RESULTS: More than 43% of oral and tracheal samples tested positive for at least one investigated pathogen at both collection time points, indicating persistent microbial colonization during mechanical ventilation. Significant positive correlations for Staphylococcus aureus detection were observed between oral and tracheal samples on Day 0 (p=0.0028) and Day 2 (p=0.0021), suggesting a possible association between oral colonization and lower airway microbial presence. Streptococcus pneumoniae detected in initial oral samples showed a significant correlation with tracheal detection after 48 h (p=0.03). Quantitative analyses demonstrated no significant changes in bacterial load over time for most microorganisms. However, Klebsiella pneumoniae showed a significant increase in tracheal bacterial load between Day 0 and Day 2 (p=0.04), with higher tracheal loads than oral samples on Day 2 (p=0.01). CONCLUSION: The oral cavity may serve as an important reservoir of respiratory pathogens in patients receiving mechanical ventilation. The observed correlations between oral and tracheal colonization and pathogen-specific colonization patterns reinforce the relevance of oral health management in critical care settings. In particular, the increase in tracheal Klebsiella pneumoniae load suggests that lower airway proliferation may occur during mechanical ventilation independently of simultaneous increases in oral bacterial load.

Humans↗
PubMed1998

Severe infection caused by Stomatococcus mucilaginosus in a neutropenic patient: case report and review of the literature.

A 24-year-old female, in neutropenic phase after chemotherapy for acute myelogenous leukemia (on day 15) was admitted in intensive care unit for infectious pneumonia. Two strains of Stomatococcus mucilaginosus were isolated from peripheral blood cultures. No microorganisms were yielded from bronchoalveolar lavage. Patient's condition improved with prompt instigation of effective antibiotic therapy. This was the first case of septicemia and pneumonia, due to Stomatococcus mucilaginosus, in our unit. Only 26 cases occurring in neutropenic patients with underlying hematologic malignancies were reported in the literature and among these, only five cases with pneumonia were described. The complications of this normal inhabitant of the human oral cavity can be serious and fatal: septic shock, meningitis, acute respiratory distress syndrome. This study illustrate the possible virulence of Stomatococcus mucilaginosus in neutropenic patients.

Acute Disease↗
PubMed1997

[Bacteriological study of oral open abscesses].

Although studies of bacteriology of closed oral abscesses have been extensively done, there are few studies on microorganisms involving open oral abscesses. We examined bacteriologically three open abscesses with precaution against bacterial contamination with oral normal flora and saliva, when sampling. The specimens were subjected to aerobic and anaerobic cultures within 2 hours after sampling. All three cases were infected with 5 to 14 species of aerobic and anaerobic bacteria; Streptococcus spp., Prevotella intermedia and other Prevotella spp. were predominant in all three cases. All six Prevotella spp. isolated were beta-lactamase producers, being resistant to beta-lactam antibiotics. These results emphasize the importance of prompt anaerobic culture for the bacteriological study of open oral abscess and the significance of nitrocefin test to detect beta-lactamase produced by oral isolates, especially Prevotella spp.

Abscess↗