Healthcare Challenges and Future Solutions in Dental Practice: Assessing Oral Antibiotic Resistances by Contemporary Point-Of-Care Approaches

Antibiotic resistance poses a global threat, which is being acknowledged at several levels, including research, clinical implementation, regulation, as well as by the World Health Organization. In the field of oral health, however, the issue of antibiotic resistances, as well as of accurate diagnosis, is underrepresented. Oral diseases in general were ranked third in terms of expenditures among the EU-28 member states in 2015. Yet, the diagnosis and patient management of oral infections, in particular, still depend primarily on empiric means. On the contrary, on the global scale, the field of medical infections has more readily adopted the integration of molecular-based systems in the diagnostic, patient management, and antibiotic stewardship workflows. In this perspective review, we emphasize the clinical significance of supporting in the future antibiotic resistance screening in dental practice with novel integrated and point-of-care operating tools that can greatly support the rapid, accurate, and efficient administration of oral antibioticspublishedVersio

Root Microbiota in Primary and Secondary Apical Periodontitis

Apical periodontitis is an inflammatory disease of the dental periradicular tissues triggered by bacteria colonizing necrotic root canals. Primary apical periodontitis results from the microbial colonization of necrotic pulp tissues. Secondary apical periodontitis results from a persistent infection of incorrectly treated root canals. The aim of this study was to characterize the microbiota present in primary and secondary intraradicular infections associated with apical periodontitis using 16S rRNA gene amplicon sequencing. Teeth exhibiting apical periodontitis with or without root canal treatment were extracted after informed consent. From each tooth, the intraradicular content as well as a dentin sample (control) were collected and subjected to DNA extraction. PCR amplicons of the V3–V4 region of the bacterial 16S rRNA gene were pooled and sequenced (2 × 300) on an Illumina MiSeq instrument. The bioinformatics analysis pipeline included quality filtering, merging of forward and reverse reads, clustering of reads into operational taxonomic units (OTUs), removal of putative contaminant OTUs and assigning taxonomy. The most prevalent and abundant OTU in both dentin and root canal samples was assigned to anaerobic bacterium Fusobacterium nucleatum. Multivariate analysis showed clustering of microbiota by sample type (dentin vs. intraradicular content) and, in root canals, by pathology (primary vs. secondary infection). The proportions of Enterococcus faecalis and F. nucleatum were, respectively, higher and lower when comparing secondary to primary infected root canals. Co-occurrence network analysis provided evidence of microbial interactions specific to the infection type. The identification of bacterial taxa differentially abundant in primary and secondary intraradicular infections may provide the basis for targeted therapeutic approaches aimed at reducing the incidence of apical periodontitis

Blue light-mediated antimicrobial photodynamic therapy on oral pathogens

Antimicrobial photodynamic therapy (aPDT) relies on the light activation of a photosensitizer to generate ROS that inactivate bacteria. This thesis investigated the efficiency of three blue light-absorbing photosensitizers, curcumin, Eosin Y and Rose Bengal, on several oral pathogens. Flow cytometry has been used to assess the antibacterial activity. Our results demonstrated that aPDT has the potential to efficiently inactivate bacteria with minimum adverse effects to host cells. Biofilms have shown a reduced susceptibility to aPDT as compared to planktonic bacteria. Optimizing aPDT parameters, such as light dose and photosensitizer delivery, was shown to increase the antibacterial effect on biofilms. Rose Bengal has demonstrated the ability to incorporate into the membranes of Gram-positive and –negative bacteria in sufficient amount to inactivate them upon blue light-irradiation. Although, aPDT has proven to be efficient against various oral pathogens, future research is warranted to improve the antibacterial activity against biofilms

Oxidative Stress in Bacteria Measured by Flow Cytometry

Cytométrie en flux pour la mesure du stress oxydatif dans les bactérie

Enzyme-mediated photoinactivation of Enterococcus faecalis using Rose Bengal-acetate

Rose Bengal-acetate (RB-Ac) is a pro-photosensitizer claimed to diffuse into target cells, where the acetate groups are hydrolyzed and the photosensitizing properties of Rose Bengal (RB) are restored. Despite promising results on tumor cells, the interaction of RB-Ac with bacteria has never been investigated. This study aimed to assess the interaction of RB-Ac with Enterococcus faecalis and to evaluate its potential use in antimicrobial photodynamic therapy (aPDT). Spectrofluorometry was used to assess the ability of E. faecalis to hydrolyze the RB-Ac compound. Fluorescence microscopy was employed to observe the distribution and to evaluate the cellular uptake of the RB produced. The antibacterial efficiency of RB-Ac-mediated aPDT was assessed by flow cytometry in combination with the LIVE/DEAD® staining. Results showed that RB-Ac was successfully hydrolyzed in the presence of E. faecalis cells. The RB produced appeared to incorporate the membrane of bacteria. Higher concentrations of RB-Ac resulted in higher incorporation of RB. The blue-light irradiation of RB-Ac-treated samples significantly reduced bacterial viability. Less than 0.01% of E. faecalis survived after incubation with 200 μM RB-Ac during 900 min and blue-light activation. The current report indicates that E. faecalis cells can hydrolyze the RB-Ac compound to produce active RB. The use of RB-Ac did not appear to allow cytoplasmic internalization of the RB produced, which rather incorporated the membrane bilayers of E. faecalis. The use of RB-Ac did not provide additional advantages over RB in terms of PS localization. Nonetheless, sufficient RB was produced and incorporated into the membranes of bacteria to elicit effective aPDT