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Background: The aim of the current study is to compare the prevalence of commensal bacteria, with beneficial properties, for healthy and diseased individuals and additionally to examine the inhibitory effect of some commercial dietary probiotics on periodontopathogens, comparing this inhibitory effect to that of orally derived beneficial bacteria., Methods: Subgingival plaque samples from 35 patients (healthy and periodontitis patients) were analyzed. Growth inhibition of the periodontal pathogens Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans was examined using the agar overlay technique and agar well diffusion method. The quantification of the inhibitory effect was checked with the agar well diffusion method., Results: Using the agar overlay technique, the prevalence of strains antagonistic toward P. gingivalis, A. actinomycetemcomitans, and F. nucleatum was found to be higher in healthy individuals than in individuals with periodontitis, but this could not be validated by the agar well diffusion assay. Compared with the antagonistic activity of the isolated strains, the probiotic strains overall showed a stronger inhibition of the periodontal pathogens., Conclusion: It was shown that some oral bacteria can cause antagonism toward periodontopathogens, and these observations underline the therapeutic potential of applications that stimulate oral health by the application of beneficial effector strains.

Recently, the predation of Bdellovibrio bacteriovorus on a periodontal pathogen has been described. The current study explores the potential antimicrobial activity of a range of predatory bacteria against key periodontal pathogens. A number of representatives from the Bdellovibrio, Bacteriovorax and Peredibacter lineages (called 'BALOs') were tested for their activity towards a group of key periodontal pathogens and an optimal multiplicity of infection was established. As the oral cavity contains a wide variety of bacteria that are not preyed upon, it was investigated if they can have an effect on the predation efficiency of BALOs. It was concluded that a number of important variables involved in bacterial predation are found to be compatible with the composition of the oral microbiota. This finding makes the case for continued study of the potential for BALOs to combat periodontal pathogens., (© 2010 John Wiley & Sons A/S.)

The aim of the study was to evaluate the effects of Listerine, Meridol, and Perioaid on the viability and total number of bacteria in established biofilms using an in vitro model under hydrodynamic conditions. Biofilms of Aggregatibacter actinomycetemcomitans were placed in a modified Robbins device and rinsed twice daily during 4 days. Bacteria were quantified by culture and quantitative polymerase chain reaction. Visualization of the samples was performed by scanning electron and confocal laser scanning microscopy, combined with a fluorescent vital staining. All three mouthrinses caused a significant reduction in the number of cultivable A. actinomycetemcomitans in a biofilm. Perioaid was significantly the most powerful in killing the biofilm-protected bacteria and also in counteracting the development of thick dense microbial communities. The total amount of bacteria was not significantly affected by Listerine and Meridol.

Aim: To monitor the intra-oral microbiological changes after full-mouth extraction using quantitative polymerase chain reaction (qPCR)., Material and Methods: Nine patients with severe, aggressive periodontitis, for whom a full-mouth tooth extraction was the only remaining treatment option were recruited. Before and 6 months after extraction, microbial samples were obtained (tongue, saliva and subgingival plaque) and analysed by qPCR., Results: The elimination of subgingival niches, by extraction of all natural teeth, resulted in a 3-log reduction of Porphyromonas gingivalis and Tannerella forsythia, and more modest reductions of Aggregatibacter actinomycetemcomitans and Prevotella intermedia. However, the detection frequencies of these periodontopathogens in saliva and on the tongue remained unchanged after full-mouth tooth extraction., Conclusion: In contrast to what has been believed so far, full-mouth tooth extraction does not result in eradication of all periodontopathogens but only in a significant reduction. The clinical consequences of this observation remain speculative.

The inflammatory response plays an important role in the tissue destruction associated with periodontitis. Bacterial species can regulate the inflammatory responses of host cells, triggered by pathogens. It was hypothesized that, in the field of oral microbiology/immunology, such effects of bacterial interactions on inflammatory host cell responses might also be present. In this study, the effects of beneficial, commensal, and pathogenic species on Aggregatibacter actinomycetemcomitans-induced interleukin-8 (IL-8) production by human cells were investigated. The beneficial species, Streptococcus mitis, Streptococcus salivarius, and Streptococcus sanguinis, were able to lower the IL-8 production triggered by A. actinomycetemcomitans. The inhibitory effect was also achieved by the application of streptococcal supernatants. In contrast, the commensal Streptococcus gordonii caused no reduction, and the pathogen Fusobacterium nucleatum increased IL-8 production by the host cells. These results show that bacterial species can influence the inflammatory responses of host cells triggered by infection with A. actinomycetemcomitans.

Introduction: Microbial interactions are considered to be important for bacterial colonization. Interactions that inhibit colonization of pathogens could possibly be used as a new treatment approach for periodontitis. The aim of this study was to test this hypothesis on soft surfaces in vitro, taking into account the hydrodynamic forces continuously present in vivo., Methods: Cultured epithelial cells were precolonized with Streptococcus sanguinis KTH-4, Streptococcus cristatus CC5A, Streptococcus salivarius TOVE and Streptococcus mitis BMS before Aggregatibacter actinomycetemcomitans colonization. Experiments were performed in a modified Robbins-device-type flow cell. Bacterial colonization and the number of epithelial cells were evaluated by microbial culturing and quantitative polymerase chain reaction., Results: The streptococci were able to inhibit A. actinomycetemcomitans colonization on soft tissue surfaces under flow conditions. Statistically significant differences were found between streptococcal pretreatments and the controls, with the most pronounced effect caused by S. sanguinis., Conclusion: These data confirm the possibility of applying beneficial bacteria in periodontal treatment.

Quantification of Bdellovibrio-and-like organisms (BALOs) by microbial culturing has a number of substantial drawbacks. Therefore a quantitative PCR (qPCR) assay was designed for the culture-independent enumeration of the Bdellovibrionaceae. After optimization, the dynamic range of the qPCR assay was assessed, the specificity was evaluated and a comparison with quantitative microbial culturing was made. To evaluate the suitability of the qPCR assay for analysing environmental samples, fresh water samples were investigated by microbial culturing and by the qPCR assay. The results revealed a substantial difference between the two techniques and indicate that most Bdellovibrionaceae cells are left undetected in environmental samples when only current microbial culturing techniques are used. The application of this new technique is therefore likely to confirm the hitherto underestimated sizes and roles of predatory bacterial populations in nature., (© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.)

Periodontitis is a polymicrobial infectious disease primarily associated with Gram-negative periodontopathogens. Bdellovibrio and like organisms are predatory bacteria that feed on Gram-negative bacteria. This study investigated whether predatory bacteria can attack Aggregatibacter actinomycetemcomitans. Therefore, A. actinomycetemcomitans was challenged with the predator Bdellovibrio bacteriovorus under conditions simulating the oral cavity. The reduction of planktonic A. actinomycetemcomitans was quantified via bacterial culture, and the development of predatory bacteria was monitored with quantitative real-time PCR. The destruction of A. actinomycetemcomitans biofilms by B. bacteriovorus was quantified by crystal violet staining and visualized by scanning electron microscopy. The in vitro results show that B. bacteriovorus can attack, prey on, and kill A. actinomycetemcomitans and suggest a potential for B. bacteriovorus as a living antibiotic for the prevention and treatment of periodontitis.

Introduction: Oral bacteria must attach to hard and soft tissues to colonize the oral cavity in the presence of a variety of forces caused by shear and flow. In vitro models mimicking this dynamic process are indispensable to study factors that might interfere with the first step towards infection. For extrapolation purposes the comparability between the dynamics of colonization on hard vs. soft surfaces needs to be evaluated., Methods: The colonization of glass and epithelial cell surfaces by the periodontal pathogen Aggregatibacter actinomycetemcomitans was followed in time with two flow cell models: a modified Robbins device (MRD) and an in situ image analysis system., Results: The number of A. actinomycetemcomitans recovered from the soft surfaces in the MRD experiments was higher than on glass. The amount of bacteria on the hard surfaces kept increasing with time, while on soft surfaces saturation was reached. The microscope-mounted flow cell allowed real-time in situ monitoring of the colonization process of both surfaces., Conclusion: These experimental models may have a great contribution to make in the development of new treatment approaches for periodontal diseases. Colonization by A. actinomycetemcomitans could be studied under flow conditions and its dynamics showed important surface-dependent characteristics.

Introduction: Microbial interactions are considered important in the adhesion process of pathogenic bacteria in the oral cavity. This study addressed the hypothesis that a streptococcal biofilm influences the hard tissue colonization by the periodontopathogen Aggregatibacter actinomycetemcomitans under hydrodynamic conditions., Methods: The colonization of a green-fluorescent-protein-labelled A. actinomycetemcomitans strain on surfaces coated with a streptococcal biofilm, was monitored in real time using a confocal laser scanning microscope-mounted flow cell. Culture and quantitative polymerase chain reaction data were obtained in parallel from a Modified Robbins Device., Results: Colonization of A. actinomycetemcomitans was inhibited by the four tested streptococci (Streptococcus sanguinis, Streptococcus cristatus, Streptococcus salivarius, and Streptococcus mitis). The most inhibiting species was S. sanguinis., Conclusion: These results confirmed the hypothesis that some bacterial species influence A. actinomycetemcomitans colonization of hard surfaces in vitro under hydrodynamic conditions.

Human rhinoviruses (HRV), responsible for approximately 60% of the common colds, are divided into two groups, according to their receptor specificity. The major group of HRVs gains access to human cells by binding to the intercellular adhesion molecule-1 (ICAM-1), whereas HRVs of the minor group use members of the low-density lipoprotein receptor (LDLR) family for cell entry. Previous studies confirmed that the HRV-binding region of ICAM-1 is located in the amino-terminal immunoglobulin-like (Ig) domain 1, which is encoded by exon 2 of the ICAM-1 gene. An A --> T transversion in codon 29 of ICAM-1 exon 2 causes a lysine to methionine substitution (K29M), and was found at a high frequency (33.2%) in Kilifi (Kenya), as well as in other African populations. In this study we examined whether polymorphisms in exon 2 of ICAM-1 could be detected in a Caucasian population, assuming that these could be of importance in HRV binding. DNA from 100 healthy, unrelated, Belgian volunteers was obtained through a noninvasive swish-and-spit method. Using a primer set in the adjacent intron sequences, the full-length ICAM-1 exon 2 was amplified by polymerase chain reaction (PCR), followed by direct sequencing of the PCR product. No polymorphisms could be demonstrated in exon 2 of the ICAM-1 gene among all 100 tested individuals. The rhinovirus-binding Ig domain 1 of ICAM-1 seems to be a highly conserved region in the Caucasian population.