Bacterial antagonism against periodontopathogens.

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.

Effect of mouthrinses on Aggregatibacter actinomycetemcomitans biofilms in a hydrodynamic model.

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.

Do periodontopathogens disappear after full-mouth tooth extraction?

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.

Absence of the Kilifi mutation in the rhinovirus-binding domain of ICAM-1 in a Caucasian population.

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.