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At least 487 records · Page 27Linked to original sources
PubMed1992

[Identification of mycoplasma by the growth inhibition of samples isolated from cell cultures].

Cell cultures must be continuously screened for the presence of mycoplasma because, although these microorganisms sometimes pass unnoticed, they may cause chromosomic alterations and interfere with viral replication, antibody and interferon production etc. The International Organization for Mycoplasmology (IOM) recommends the isolation and identification of mycoplasma with a view to the detection of the origin of the infection and the improvement of the quality of the cultures. In this paper, 37 samples belonging to 27 cell lines contaminated with mycoplasma were assayed by the growth inhibition test. It is known that Mycoplasma orale is the most common human mycoplasma contaminant of cell cultures, the major vehicle of contamination being mouth pippeting, while commercial bovine serum in the main source for Mycoplasma arginini and Acholeplasma laidlawii. M. arginini was found in 18 (48.65%) of the cell samples tested, A. laidlawii in 15 (40.55%), and M. orale in two (5.40%). Two other samples could not be identified by the antisera used (antisera against M. arginini, M. orale, Mycoplasma hyorhinis and A. laidlawii) their characteristics being "fried egg" colonies, digitonine sensitivity, Dienes stained, positive glucose catabolism, negative arginini hydrolysis, and negative tetrazolium reduction. No more than one type of mycoplasma was found in each cell culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriological Techniques↗
PubMed2000

The impact of advances in dental sciences on primary dental care.

The next century will see phenomenal changes especially and, most importantly, in patient empowerment, in the improvement of health in the disadvantaged, and in the harmonisation of standards of healthcare throughout the world. Advances in the dental sciences will facilitate these improvements but the major changes surely will be largely stimulated and motivated by the information revolution and the advances in molecular and materials sciences. The identification, and protection against disease, of patients who, because of a genetic predisposition, are at particular risk of disease is likely to become possible. Simple, sensitive, effective, non-invasive and safe diagnostic procedures will become available, as will chairside diagnostic test kits that would identify specific microorganisms causal of oral disease. The advances in digital imaging will be taken further and linked to record-keeping. Specific safe agents targeted at responsible microorganisms will be devised, and systems to deliver therapeutic agents effectively and prevent tissue damage simply will be perfected. Painless, minimally-invasive techniques for the removal of diseased oral tissues will become available, as will biocompatible materials for replacement of lost oral tissues.

Anti-Infective Agents↗
PubMedDate not supplied

Retention of oral microorganisms on conventional and resin-modified glass-ionomer cements.

Secondary caries are a worldwide public and socioeconomic problem. The placement of restorations can lead to the development of environmental conditions favorable to microbial colonization, especially on the tooth/restoration interface, which is a predisposing factor for secondary caries. The aim of this study was to evaluate microbial retention on conventional (Chelon-Fil and Vidrion R) and resin-modified (Vitremer and Fuji II LC) glass-ionomer cements, in situ, using a hybrid composite resin (Z100) as a control. Twelve volunteers wore Hawley appliances with specimens made of all tested filling materials for 7 days. The specimens were then removed from the appliances and transferred to tubes containing 2.0 ml of Ringer-PRAS. Microorganisms from the samples were inoculated onto blood agar and Mitis Salivarius Bacitracin agar and incubated under anaerobiosis (90% N2, 10% CO2), at 37 degrees C, for 10 and 2 days, respectively. The resin-modified glass-ionomer cements and the composite resin retained the same levels of microorganisms on their surfaces. The resin-modified glass-ionomers retained less mutans streptococci than the composite resin and conventional glass-ionomer cements. The conventional glass-ionomer cements retained less mutans streptococci than the composite resin, but that difference was not statistically significant.

Adult↗
PubMed1982

In vitro hydrolysis of monofluorophosphate by dental plaque microorganisms.

Enzymic hydrolysis of sodium monofluorophosphate by suspensions of dental microorganisms has been demonstrated at pH 5.1, pH 7.0, and pH 8.4, using a fluoride-selective electrode. The extracellular medium from viable Streptococcus mutans K1R cells contained low MFPase and paranitrophenyl phosphatase activity. It is hypothesized that the enzymes responsible for MFP hydrolysis by S. mutans K1R are intracellular, and that cell disruption is necessary for hydrolysis to be manifested; this question requires further study. In vitro MFPase activity was of a magnitude consistent with the hypothesis that it may significantly raise the fluoride ion concentration of plaque within the several minutes MFP would be in the mouth during toothbrushing.

Bacteria↗
PubMed2000

[Antimicrobial effects of tea tree oil (Melaleuca alternifolia) on oral microorganisms].

The essential oil of Melaleuca alternifolia (tea tree oil) exhibits antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria, yeasts and fungi. In this study the bacteriostatic and bacteriocidal/fungicidal activity of a tea tree oil solution, of a new tea tree oil (Tebodont) and the respective placebo-gel, of a chlorhexidindigluconate-solution and of PlakOut was tested in vitro against ten different oral microorganisms. Minimum inhibitory concentrations were in the range from 0.0293% to 1.25% for the tea tree oil solution and from 0.0082% to 1.25% for the tea tree oil gel. The values for minimum bacteriocidal/fungicidal concentrations were in the range from 0.0521% to 2.5% for the tea tree oil solution and from <0.0098% to 3.33% for the tea tree oil gel. The most susceptible microorganisms were Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis, whereas Streptococcus mutans and Prevotella intermedia were the least susceptible ones. Both for the chlorhexidindigluconate solution and for PlakOut the values for the minimal inhibitory concentration and for the minimal cidal concentration were between <0.0002% and 0.0125%.

Anti-Infective Agents, Local↗
PubMed1980

[Teeth and nutrition (basic questions)].

Recognized methods used in the science of nutrition are only applicable to a limited extent for nutrition aspects of dental health; the necessity of using more highly differentiated methods of measurement was substantiated. The consumption trends for the most important groups of foodstuffs in recent years was discussed, based on data from the 1980 report on nutrition; nutrient supply and an evaluation of consumption statistics were considered and possibilities for necessary improvements were mentioned. Using the example of theoretical and recent test results for sugar exchange substances, it was shown how many different ways must be considered for symbiosis between man and microorganisms (namely, including lower sections of the intestine) in evaluating foodstuff safety for sugar exchange substances. Those aspects of nutrition control, particularly in regard to dentistry, arising from this study were discussed in a separate section which promote a further development in the relationship between dentistry and the science of nutrition.

Colon↗
PubMed2000

Oral mucosal Langerhans' cells as target, effector and vector in HIV infection.

The mechanism underlying a transition of the oral cavity mucosal epithelium towards susceptibility to opportunistic infections in HIV-seropositive patients was investigated. Phenotypic markers CD1a, HLA-DR, and CD86 of oral mucosal Langerhans' cells (LCs), p17 core protein of human immunodeficiency virus (HIV), and CD45RO of memory T cells were labeled on oral hairy leukoplakia lesional biopsies and clinically normal autologous tissue of HIV-infected patients. HIV p17 protein was detected in association with mucosal LCs, mainly within the lesional epithelium. There were significant correlations between the detection of HIV p17 and the depletion of LCs, and between the depletion of LCs and the presence of hairy leukoplakia lesions. Conjugates of activated LCs and memory T cells were also evident in the submucosal area of lesional biopsies. The findings from this study support the hypothesis that oral mucosal LCs are also the target of HIV infection. Cytopathic changes of LCs caused by productive HIV infection may contribute to selective depletion of LCs, which may impair the mucosal immunologic protection against colonization by microorganisms causing HIV-associated oral mucosal lesions.

AIDS-Related Opportunistic Infections↗
PubMed1984

Cariogenicity of sorbitol.

Sorbitol is a commonly used sweetener in many so called sugar-free products, like chewing-gums, lozenges and medicines. It is also used as a stabilizer in tooth pastes and is found naturally in some fruits and berries. Many methods have been used to evaluate the cariogenicity of sorbitol, e.g. short and long term studies in man, animal experiments and pH-measurements in dental plaque in vivo and in vitro. Most of these studies indicate that sorbitol has a low or no cariogenicity. However, there are some data showing that frequent consumption of sorbitol may result in an increased acid production in dental plaque and in an increased number of sorbitol-fermenting microorganisms. This adaptation is probably of no or only minor clinical importance, at least for persons with a normal salivary function and for people with a moderate consumption of sorbitol-containing products. Thus, present knowledge shows that sorbitol might be considered as a "low cariogenic" sugar substitute.

Acids↗
PubMed1985

Survival of herpes simplex virus and other selected microorganisms on patient charts: potential source of infection.

This study indicated that when inoculated onto dental charts, both viruses and bacteria were capable of survival allowing the potential for transmission of infection within the dental office. The conscientious dental practitioner can take steps to reduce this possible mode of infection by removing contaminated surgical gloves or washing hands before handling the chart. An additional method of reducing this potential would be to wipe the chart with an antiseptic solution. Although this study has shown that there is a potential for the spread of infection with the organisms tested, the actual extent of dental chart contamination and resultant illnesses contracted are the basis for further study. Additional studies are needed to follow the pattern of chart distribution from person to person within the dental office, determine the types and quantities of pathogens present in the mouth that would contaminate the charts, and sample the charts under actual clinical conditions to determine the types and viability of the organisms present.

Bacterial Physiological Phenomena↗
PubMed2006

Role of oxyR in the oral anaerobe Porphyromonas gingivalis.

Porphyromonas gingivalis is an anaerobic microorganism that inhabits the oral cavity, where oxidative stress represents a constant challenge. A putative transcriptional regulator associated with oxidative stress, an oxyR homologue, is known from the P. gingivalis W83 genome sequence. We used microarrays to characterize the response of P. gingivalis to H2O2 and examine the role of oxyR in the regulation of this response. Most organisms in which oxyR has been investigated are facultative anaerobes or aerobes. In contrast to the OxyR-regulated response of these microorganisms to H2O2, the main feature of the response in P. gingivalis was a concerted up-regulation of insertion sequence elements related to IS1 transposases. Common OxyR-regulated genes such as dps and ahpFC were not positively regulated in P. gingivalis in response to H2O2. However, their expression was dependent on the presence of a functional OxyR, as revealed by microarray comparison of an oxyR mutant to the wild type. Phenotypic characterization of the oxyR mutant showed that OxyR plays a role in both the resistance to H2O2 and the aerotolerance of P. gingivalis. Escherichia coli and other bacteria with more complex respiratory requirements use OxyR for regulating resistance to H2O2 and use a separate regulator for aerotolerance. In P. gingivalis, the presence of a single protein combining the two functions might be related to the comparatively smaller genome size of this anaerobic microorganism. In conclusion, these results suggest that OxyR does not act as a sensor of H2O2 in P. gingivalis but constitutively activates transcription of oxidative-stress-related genes under anaerobic growth.

Anaerobiosis↗
PubMed1996

Periodontal diseases: epidemiology.

1. The interpretation of epidemiological data of periodontal disease is difficult, due to inconsistencies in the methodology used. It is not possible, therefore, to accurately assess if the prevalence of the periodontal diseases shows a world-wide decline. As long as the disease is assessed through accumulated clinical attachment loss, retention of the natural dentition in older ages entails increased prevalence in these cohorts. Contemporary epidemiological studies should ideally employ full-mouth examination of the periodontal tissues. Partial recording estimates are generally biased, especially when the prevalence of the disease is low. 2. Early-onset periodontitis is infrequent in all populations. Adult periodontitis is rather prevalent; however, advanced disease affects limited subfractions of the population (probably less than 10 to 15%). Although prevalence figures vary with race and geographic region, in most cases, the progression pattern of the disease seems compatible with the retention of a functional dentition throughout life. 3. Of a plethora of behavioral and environmental risk markers identified by multi-variate analysis, smoking and presence of certain subgingival microorganisms have been proven to be true risk factors. The same holds true for diabetes mellitus, a systemic condition that confers a risk for periodontal disease which is independent of the effect of other significant factors. 4. In certain cases, periodontal infections appear to have a systemic impact on the host. Most recent data indicate that periodontal disease may confer risk for coronary heart disease and pre-term low birth weight.

Adolescent↗
PubMed2006

Where do the immunostimulatory effects of oral proteolytic enzymes ('systemic enzyme therapy') come from? Microbial proteolysis as a possible starting point.

Enteric-coated proteolytic enzyme preparations like Wobenzym and Phlogenzym are widely used for the so-called 'systemic enzyme therapy' both in humans and animals. Numerous publications reveal that oral proteolytic enzymes are able to stimulate directly the activity of immune competent cells as well as to increase efficiency of some of their products. But origins of the immunostimulatory effects of oral proteolytic enzymes are still unclear. The hypothesis described here suggests that it may be proteolysis of intestinal microorganisms that makes the immune competent cells to work in the immunostimulatory manner. The hypothesis was largely formed by several scientific observations: First, microbial lysis products (lipopolysaccharides, muropeptides and other peptidoglycan fragments, beta-glucans, etc.) are well known for their immunostimulatory action. Second, a normal human being hosts a mass of intestinal microorganisms equivalent to about 1 kg. The biomass (mainly due to naturally occurring autolysis) continuously supplies the host's organism with immunostimulatory microbial cell components. Third, the immunostimulatory effects resulting from the oral application of exogenously acting antimicrobial (lytic) enzyme preparations, such as lysozyme and lysosubtilin, are likely to be a result of the action of microbial lysis products. Fourth, cell walls of most microorganisms contain a considerable amount of proteins/peptides, a possible target for exogenous proteolytic enzymes. In fact, several authors have already shown that a number of proteases possess an ability to lyse the microbial cells in vitro. Fifth, the pretreatment of microbial cells (at least of some species) in vitro with proteolytic enzymes makes them more sensitive to the lytic action of lysozyme and, otherwise, pretreatment with lysozyme makes them more susceptible to proteolytic degradation. Sixth, exogenous proteases, when in the intestines, may participate in final steps of food-protein digestion. The resulting food-borne peptides have recently been shown to be potential activators of microbial autolysis. The main question that needs to be answered in order to verify the hypothesis is whether oral proteases are able (and to what extent) to lyse/mediate lysis of intestinal microorganisms in situ. Methods based on up-to-date molecular biology techniques to allow investigation of the influence of exogenous proteases on microbial lysis processes in vivo (in the intestines) need to be developed. Research testing of this hypothesis may have an important impact in development of novel preparations for the systemic enzyme therapy.

Adjuvants, Immunologic↗
PubMed1975

Antibiotic efficacy in odontogenic infections.

Cultures and antibiotic sensitivities were determined for 84 patients in the oral surgery clinic who had diagnoses of odontogenic infections. Data tabulated from the results of the bacteriologic cultures and antibiotic sensitivities disclosed the five organisms most frequently involved. Antibiotic efficacy for each of the antibiotics used in sensitivity determinations was calculated on the basis of the percent sensitivity of a given organism to the given antibiotic, and the percent of patients with infections resulting from the given organism, both expressed as decimals. Antibiotics were then arranged in order of greatest to least efficacy on the basis of chloramphenicol as 100 percent. Efficacy values, sigma and lambda, were compared for the antibiotics. It was concluded that those antibiotics below penicillin on the efficacy table were less useful in the initial antibiotic treatment of odontogenic infections. Chloramphenicol was effective against every microorganism isolated during this investigation, but its use should be tempered with clinical judgment. Erythromycin should be given consideration as a replacement for penicillin as the preferred drug in the initial treatment of odontogenic infections on the basis of its high efficacy rating and freedom from potentially serious allergic or other untoward manifestations.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Staphylococcal colonization of the oral cavity of children following an acute form of rubella infection].

The children were being observed during the course of acute rubella infection and postinfectious period. Quantitative dynamic changes in the normal microflora composition were noted weekly during the first month of the disease as well as in the beginning of the second and the third months. The amount of microorganisms registered 3 weeks and in the beginning of the second month after the onset of rubella infection differed from that in the controls. The identification of the Staphylococcus genus microorganisms has shown an increased number of carriers during the first week, as well as on the third week from the onset of the disease. During these periods a secondary immunodeficiency is supposed to develop in children resulting in exacerbation of bacterial infections.

Child↗
PubMed1997

Subgingival microbiota in adult Chinese: prevalence and relation to periodontal disease progression.

The "checkerboard" Dna-Dna hybridization technology was used to study the epidemiology of 18 microbial species associated with various states of periodontal health and disease, in a sample of 148 Chinese subjects never exposed to systematic dental therapeutic intervention, aged 30 to 39 and 50 to 59 years. Our aims were to: 1) describe the prevalence of these microorganisms; 2) correlate the microbiological and clinical profiles of the subjects; and 3) examine the association between the microbiological variables and the longitudinal changes of periodontal status that occurred over a preceding 10-year period. A maximum of 14 subgingival samples were obtained from each subject-1,864 in all. The frequency of occurrence of the 18 species examined was high in this Chinese population, on both the subject and the tooth site level. However, all species were not found equally capable of reaching high numbers in the subgingival samples and, as a rule, colonized heavily only limited proportions of tooth sites within each mouth. There was a profound increase of certain species such as Porphyromonas gingivalis, Treponema denticola, and Bacteroides forsythus in deep pockets or progressing sites. Multivariate techniques using the subgingival profile could effectively discriminate between deep/shallow pockets and progressing/ stable tooth sites. The microbiological variables showed an enhanced discriminating potential when classifications were performed on the individual subject level. Colonization by P. gingivalis, B. forsythus, Campylobacter rectus, and T. denticola at levels exceeding certain thresholds entailed a significantly increased probability (odds ratios > 4) for an individual subject to harbor deep pockets or progressing tooth sites.

Adult↗
PubMed1988

Colonization resistance of the human intestinal microflora: testing the hypothesis in normal volunteers.

Colonization resistance is the mechanism whereby the intestinal microflora protects itself against incursion by new and often harmful microorganisms. Some authors have claimed that colonization resistance is related to the integrity of the anaerobic flora, but this point has not been established in humans. In previous studies in our laboratory cefoxitin, piperacillin, cefoperazone or aztreonam were administered intravenously to healthy volunteers in order to study changes in the intestinal flora and acquisition of new strains. Seven of 16 antibiotic-treated subjects were colonized with gram-negative bacilli, but no correlation was observed between this colonization and the suppression of either anaerobes or any other component of the fecal flora. Marked strains of Escherichia coli and Pseudomonas aeruginosa were also administered by mouth in order to test acquisition of new bacteria. The fed bacteria were found in the stools of both antibiotic-treated and control subjects; the antibiotics had no apparent influence on the ability of these strains to colonize the intestinal tract. Our work, along with findings of others, supports the concept that colonization resistance occurs in humans and is diminished by antibiotic administration. However, it does not support the hypothesis that colonization resistance is related to the anaerobic microflora.

Anti-Bacterial Agents↗
PubMed1981

Bacterial endocarditis. A retrospective study of cases admitted to the University of Alabama Hospitals from 1969 to 1979.

A retrospective study was conducted at the University of Alabama in Birmingham Medical Center on patients diagnosed as having BE from the years 1969 to 1979, with emphasis on dental involvement. A major finding of this report revealed that 16 percent of the cases of BE had a history of recent dental care or pathology. Other results of this investigation included the following: (1) Streptococcus viridans was the predominant microorganism associated with BE; (2) the mortality rate relative to predisposing heart disease was highest for patients with prosthetic heart valves; (3) chronic valvular heart disease was the heart problem most susceptible to BE; (4) chronically abscessed teeth and periodontal disease may be initiating factors of BE.

Adolescent↗
PubMed1995

The effect of periodontal parameters on the subgingival microbiota around implants.

The study aimed to examine the relationship between the subgingival flora around implants and their periodontal parameters. Plaque samples from 561 implants (279 patients) were analyzed by means of differential phase contrast microscopy and compared with the sample site's probing depth, bleeding tendency on probing, and plaque and gingivitis indices. If possible, one implant with deep and one with shallow pockets were selected within the same patient. The impact of the intraoral exposure time on the microbial composition around the implants was examined cross-sectionally, with the same group of patients. Only tendencies can be detected by the latter, and no concrete conclusions can be drawn. From the clinical parameters, increased probing depth was found to detrimentally increase the proportion of spirochetes and motile organisms, whereas the other parameters were found to be of minor importance. For partially edentulous patients only, there was a tendency for increased proportions of spirochetes and motile organisms the longer the intraoral exposure time. These observations emphasize the importance of the periodontal health of the remaining teeth (as a reservoir of pathogenic microorganisms) in partial edentulous patients rehabilitated by means of implants and indicate the importance of shallow pockets around implants (flap trimming when aesthetics and phonetics allow).

Bacteria↗