BACKGROUND AND OBJECTIVE

Orthodontic brackets predispose dental biofilm accumulation causing caries and gingivitis. Chlorhexidine is an adjunct to mechanical plaque removal, but has side-effects (tooth staining, bacterial resistance) due to long term use. This study tested the efficacy of Photodynamic Therapy, which produces reactive oxygen species, to reduce Streptococcus mutans in dental biofilm on orthodontic brackets.

A 5-day S. mutans biofilm was grown on forty enamel-bracket specimens. Thirty-nine specimens were randomized to three treatment groups: A. Distilled Water; B. 0.12% Chlorhexidine (CHX); C. Photodynamic Therapy (PDT) using Toluidine Blue O (TBO) as a photosensitizer, activated by red LED (630nm). After treatment, one random specimen from each group was viewed under Environmental Scanning Electron Microscopy (ESEM); the other 12 specimens, biofilms were collected, weighed, and cultured onto BHI agar plates to determine the number of CFU/mg. For baseline evaluation, one clean and one untreated specimens were preserved for ESEM.

Based on Tukey HSD test, group A had the most S. mutans (37.0573 CFU/mg) and was significantly different (p < 0.05) from groups B (0.1712 CFU/mg) and C (1.1193 CFU/mg), where both showed less bacteria than group A. The statistical difference between groups B and C was insignificant. ESEM images showed specimen A covered with more abundant and denser S. mutans biofilm than specimens B and C, with almost similar morphology showing sparse, less dense, and disintegrated biofilm with unclear cellular walls and presence of amorphous masses.

Both Photodynamic Therapy and 0.12% Chlorhexidine showed a significant reduction of S. mutans in dental biofilm on orthodontic brackets. However, there is no significant difference between them in reducing S. mutans CFU/mg. Photodynamic therapy could be an alternative adjunctive tool to mechanical removal of plaque adhered to orthodontic brackets.

BACKGROUND AND OBJECTIVE

Orthodontic brackets predispose dental biofilm accumulation causing caries and gingivitis. Chlorhexidine is an adjunct to mechanical plaque removal, but has side-effects (tooth staining, bacterial resistance) due to long term use. This study tested the efficacy of Photodynamic Therapy, which produces reactive oxygen species, to reduce Streptococcus mutans in dental biofilm on orthodontic brackets.

A 5-day S. mutans biofilm was grown on forty enamel-bracket specimens. Thirty-nine specimens were randomized to three treatment groups: A. Distilled Water; B. 0.12% Chlorhexidine (CHX); C. Photodynamic Therapy (PDT) using Toluidine Blue O (TBO) as a photosensitizer, activated by red LED (630nm). After treatment, one random specimen from each group was viewed under Environmental Scanning Electron Microscopy (ESEM); the other 12 specimens, biofilms were collected, weighed, and cultured onto BHI agar plates to determine the number of CFU/mg. For baseline evaluation, one clean and one untreated specimens were preserved for ESEM.

Based on Tukey HSD test, group A had the most S. mutans (37.0573 CFU/mg) and was significantly different (pCONCLUSION

Both Photodynamic Therapy and 0.12% Chlorhexidine showed a significant reduction of S. mutans in dental biofilm on orthodontic brackets. However, there is no significant difference between them in reducing S. mutans CFU/mg. Photodynamic therapy could be an alternative adjunctive tool to mechanical removal of plaque adhered to orthodontic brackets.

Facing the increasingly severe energy shortage and environmental pollution, electrocatalytic processes using electroactive microorganisms provide a new alternative for achieving environmental-friendly production. Because of its unique respiratory mode and electron transfer ability, Shewanella oneidensis MR-1 has been widely used in the fields of microbial fuel cell, bioelectrosynthesis of value-added chemicals, metal waste treatment and environmental remediation system. The electrochemically active biofilm of S. oneidensis MR-1 is an excellent carrier for transferring the electrons of the electroactive microorganisms. The formation of electrochemically active biofilm is a dynamic and complex process, which is affected by many factors, such as electrode materials, culture conditions, strains and their metabolism. The electrochemically active biofilm plays a very important role in enhancing bacterial environmental stress resistance, improving nutrient uptake and electron transfer efficiency. This paper reviewed the formation process, influencing factors and applications of S. oneidensis MR-1 biofilm in bio-energy, bioremediation and biosensing, with the aim to facilitate and expand its further application.
Bioelectric Energy Sources/microbiology* ; Biofilms ; Electrodes ; Electron Transport ; Shewanella/metabolism*

OBJECTIVE: To construct a model of Enterococcus faecalis (E. faecalis) infection in dentinal tubules by gradient centrifugation and to evaluate the antibacterial effect of low-temperature plasma on E. faecalis in dentinal tubules. METHODS: Standard dentin blocks of 4 mm×4 mm×2 mm size were prepared from single root canal isolated teeth without caries, placed in the E. faecalis bacterial solution, centrifuged in gradient and incubated for 24 h to establish the model of dentinal tubule infection with E. faecalis. The twenty dentin blocks of were divided into five groups, low-temperature plasma jet treatment for 0, 5 and 10 min, calcium hydroxide paste sealing for 7 d and 2% chlorhexidine gel sealing for 7 d. Scanning electron microscopy and confocal laser scanning microscope were used to assess the infection in the dentinal tubules and the antibacterial effect of low-temperature plasma. RESULTS: The results of scanning electron microscopy and confocal laser scanning microscopy showed that after 24 h of incubation by gradient centrifugation, E. faecalis could fully enter the dentinal tubules to a depth of more than 600μm indicating that this method was time-saving and efficient and could successfully construct a model of E. faecalis infection in dentinal tubules. Low-temperature plasma could enter the dentinal tubules and play a role, the structure of E. faecalis was still intact after 5 min of low-temperature plasma treatment, with no obvious damage, and after 10 min of low-temperature plasma treatment, the surface morphology of E. faecalis was crumpled and deformed, the cell wall was seriously collapsed, and the normal physiological morphology was damaged indicating that the majority of E. faecalis was killed in the dentinal tubules. The antibacterial effect of low-temperature plasma treatment for 10 min exceeded that of the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d. These two chemicals had difficulty entering deep into the dentinal tubules, and therefore only had a few of antibacterial effect on the bacterial biofilm on the root canal wall, and there was also no significant damage to the E. faecalis bacterial structure. CONCLUSION Gradient centrifugation could establish the model of E. faecalis dentin infection successfully. Low-temperature plasma treatment for 10 min could kill E. faecalis in dentinal tubules effectively, which is superior to the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d.
Chlorhexidine/pharmacology* ; Calcium Hydroxide/pharmacology* ; Enterococcus faecalis/physiology* ; Temperature ; Dentin ; Biofilms ; Anti-Bacterial Agents/pharmacology* ; Root Canal Irrigants/pharmacology* ; Dental Pulp Cavity

OBJECTIVE: To investigate the inhibitory effects of levofloxacin (LEV) combined with cellulase against bacille CalmetteGuerin (BCG) biofilms in vitro. METHODS: The mature growth cycle of BCG biofilms was determined using the XTT method and crystal violet staining. BCG planktonic bacteria and BCG biofilms were treated with different concentrations of LEV and cellulose alone or jointly, and the changes in biofilm biomass were quantified with crystal violet staining. The mature BCG biofilm was then treated with cellulase alone for 24 h, and after staining with SYTO 9 and Calcofluor White Stain, the number of viable bacteria and the change in cellulose content in the biofilm were observed with confocal laser scanning microscopy. The structural changes of the treated biofilm were observed under scanning electron microscopy. RESULTS: The MIC, MBC and MBEC values of LEV determined by broth microdilution method were 4 μg/mL, 8 μg/mL and 1024 μg/mL, respectively. The combined treatment with 1/4×MIC LEV and 2.56, 5.12 or 10.24 U/mL cellulase resulted in a significant reduction in biofilm biomass (P < 0.001). Cellulase treatments at the concentrations of 10.24, 5.12 and 2.56 U/mL all produced significant dispersion effects on mature BCG biofilms (P < 0.001). CONCLUSION LEV combined with cellulose can effectively eradicate BCG biofilm infections, suggesting the potential of glycoside hydrolase therapy for improving the efficacy of antibiotics against biofilmassociated infections caused by Mycobacterium tuberculosis.
Levofloxacin/pharmacology* ; Gentian Violet/pharmacology* ; BCG Vaccine/pharmacology* ; Anti-Bacterial Agents/pharmacology* ; Biofilms ; Cellulases/pharmacology* ; Microbial Sensitivity Tests

Experimental model of Pseudomonas aeruginosa biofilm was established in vitro by using biofilm reactor. The aim of this study was evaluating the removal effect of two kinds of water flowing through bactericide resin on Pseudomonas aeruginosa biofilm, and exploring the effectiveness of continuous treatment with low concentration disinfection factor on dental unit waterlines. The experimental group selected 1-2 mg/L iodinated resin (IR) filtered water and bromined hydantoin resin (BHR) filtered water with the control group selecting the sterile distilled water. Biofilms were treated by using the immersion method for 3, 7, 10, 20, and 40 days. Total viable count (TVC) and laser confocal microscopy method (CLSM) were selected to evaluate the biofilm removal effect. The result of TVC showed that in group IR, the bacterial clearance after the treatment of 3, 7, 10, and 20 days was lower than 99.9% and unqualified. The bacterial clearance after the treatment of 40 days was 99.9%,which is qualified. In group BHR, it was lower than 99.9% and unqualified after the treatment of 3, 7, and 10 days. It was and 99.99%, 100.00% after the treatment of 20, 40 days, respectively. The result of CLSM showed that before treatment, Pseudomonas aeruginosa biofilm showed a sheet and mass distribution. The bacterial coverage was 19.24%±1.97%. The proportion of viable bacteria was 93.91%±1.39%, and the biofilm matrix coverage was 17.69%±1.11%. After 20 days of treatment, the biofilm was decreased in the IR group, with the biofilm bacterial coverage reducing to 6.77%±1.61%, the proportion of live bacteria reducing to 54.85%±5.65%, and the biofilm matrix coverage reducing to 2.41%±0.85%.There was significant difference from the pre-treatment and the control (F=359.996,P<0.001). No biofilm-like structure was found in the BHR group. After 40 days of treatment, there was still a small amount of biofilm matrix residue in the IR group, with no bacterial coverage observed. The biofilm matrix coverage was 0.67%±0.47% (F=1 021.373,P<0.001). No biofilm-like structure was found in the BHR group. In conclusion, the continuous application of BHR filter water has more advantages in killing microorganisms in biofilms, removing live and dead bacteria and biofilm matrix in biofilms. Treatment water containing corresponding low concentration disinfection factors can play an important role in the field of biofilm control in dental unit waterlines.
Humans ; Disinfection/methods* ; Pseudomonas aeruginosa ; Biofilms ; Water/pharmacology*

To develop antimicrobials against Staphylococcus aureus by high throughput screening of drug library. The type of this study is experimental research. The clinical isolates of S. aureus were collected from the sputum samples of respiratory inpatient department of the Third Xiangya Hospital of Central South University. The anti-planktonic cells growth inhibition activity of FDA-approved drugs library (including 1 573 molecules) was assessed by building a planktonic cells screening platform; The biofilm inhibitory effect of the FDA-approved drugs was detected by building a biofilm screening platform combined with crystal violet staining; Minimal inhibitory concentrations of the selected hits were determined by broth microdilution assay. Finally, the cytotoxicity of the selected hits was detected by CCK-8 assay. The results showed that 218 hits were exhibited effective growth inhibitory effects against S. aureus by setting the concentrations of the molecules in the FDA-approved library to 100 μmol/L. These selected molecules are mainly anti-infective drugs, accounting for 118 hits; Followed by anti-cancer drugs, anti-inflammatory/-immune drugs, neurological drugs, cardiovascular drugs, endocrine drugs, and metabolic disease drugs, which accounts for 40, 19, 12, 9, 8, and 3 hits; Other unclassified drugs accounts for 9 hits. The top 10 hits exhibiting anti-planktonic cells activity against S. aureus were mainly including antitumor drugs, followed by neurological drugs and unclassified drugs like vitamin K3 with the inhibition rate of 99.65%-100%. Similarly, the top 10 hits showing biofilm inhibitory effects against S. aureus were also mainly including antitumor drugs, followed by neurological drugs and anti-inflammatory/-immune drugs with the inhibition rate of 50.22%-92.95%. The minimal inhibitory concentration (MIC) of the 51 hits by second round screening was determined by micro-dilution assay, which mainly include the antitumor drugs, cardiovascular drugs, endocrine drugs, anti-inflammatory/-immune drugs, metabolic disease drugs, neurological drugs and other unclassified drugs accounted for 22, 5, 3, 9, 2, 5 and 5 hits, respectively, with the MICs of 1.56-50 μmol/L, 6.25-25 μmol/L, 6.25-25 μmol/L, 0.2-50 μmol/L, 25-50 μmol/L, 1.56-50 μmol/L and 0.1-12.5 μmol/L, respectively. In conclusion, the minimum inhibitory concentrations of small molecules screened through high-throughput assay are at the level of micromolar with strong drug development potential and high modifiability. The high effective anti-planktonic cells and anti-biofilm activity by these molecules are expected to provide new ideas for the development of new antimicrobials against S. aureus.
Humans ; Staphylococcus aureus ; Anti-Bacterial Agents/pharmacology* ; High-Throughput Screening Assays ; Staphylococcal Infections ; Anti-Infective Agents/pharmacology* ; Microbial Sensitivity Tests ; Biofilms ; Antineoplastic Agents/pharmacology* ; Anti-Inflammatory Agents/pharmacology* ; Cardiovascular Agents/pharmacology* ; Metabolic Diseases

Oligonucleotide drugs have the characteristics of targeting, modifiability and high biosafety. Recent studies have shown that oligonucleotide can be used to make biosensors, vaccine adjuvants, and has the functions of inhibiting alveolar bone resorption, promoting jaw and alveolar bone regeneration, anti-tumor, destroying plaque biofilm, and precise control of drug release. Therefore, it has a broad application prospect in the field of stomatology. This article reviews the classification, action mechanism and research status of oligonucleotide in stomatology. The aim is to provide ideas for further research and application of oligonucleotide.
Humans ; Alveolar Bone Loss ; Biofilms ; Bone Regeneration ; Oligonucleotides ; Oral Medicine

Humans ; Otitis Media, Suppurative ; Chronic Disease ; Biofilms ; Otitis Media

OBJECTIVE: This study aimed to investigate whether the VCA0560 gene acts as an active diguanylate cyclase (DGC) in Vibrio cholerae and how its transcription is regulated by Fur and HapR. METHODS: The roles of VCA0560 was investigated by utilizing various phenotypic assays, including colony morphological characterization, crystal violet staining, Cyclic di-GMP (c-di-GMP) quantification, and swimming motility assay. The regulation of the VCA0560 gene by Fur and HapR was analyzed by luminescence assay, electrophoretic mobility shift assay, and DNase I footprinting. RESULTS: VCA0560 gene mutation did not affect biofilm formation, motility, and c-di-GMP synthesis in V. cholerae, and its overexpression remarkably enhanced biofilm formation and intracellular c-di-GMP level but reduced motility capacity. The transcription of the VCA0560 gene was directly repressed by Fur and the master quorum sensing regulator HapR. CONCLUSION Overexpressed VCA0560 functions as an active DGC in V. cholerae, and its transcription is repressed by Fur and HapR.
Vibrio cholerae/genetics* ; Biofilms ; Quorum Sensing ; Mutation ; Gene Expression Regulation, Bacterial ; Bacterial Proteins/genetics*