Tatiane Tiemi Macedo

Background: Tracheostomy procedures are associated with increased risk of nosocomial infections due to microbial colonization and biofilm formation on tube surfaces. These biofilms contribute to persistent infections and hinder clinical recovery. Plant-derived products have gained interest as alternative strategies for preventing device-associated infections. Methods: This study evaluated the phytochemical composition and the antimicrobial, anti-adherent, antibiofilm, anti-inflammatory, antioxidant, and toxicity properties of Tapirira obtusa bark extract (TOBE). Antimicrobial activity was determined by minimum inhibitory concentrations (MICs). Biofilm formation and microbial viability were assessed in mono- and mixed-species biofilms. Anti-inflammatory effects were evaluated by NF-κB inhibition and TNF-α quantification. Antioxidant activity was measured using the DPPH assay. Phytochemical analysis identified major bioactive groups, and toxicity was tested in the Galleria mellonella model. Results: TOBE exhibited notable antimicrobial activity, with MIC values between 3.9 and 31.25 µg/mL. At 78 µg/mL, the extract significantly reduced biofilm biomass and microbial viability (p < 0.05). TOBE also downregulated NF-κB activation and decreased TNF-α levels. Antioxidant assays confirmed radical-scavenging capacity. Phytochemical screening revealed phenolics, flavonoids, and tannins, and toxicity results indicated a safe profile. Conclusion: TOBE effectively inhibits microbial growth and biofilm development on orotracheal tube surfaces while exhibiting anti-inflammatory and antioxidant properties without detectable toxicity. These findings support its potential as a plant-based adjunct for preventing tracheostomy-related infections and improving patient outcomes.

Background: Periodontal disease (PD) is a chronic inflammatory condition associated with dysbiotic biofilm, leading to the destruction of bone and periodontal ligament. Scaling and root planing (SRP) is the gold-standard treatment for PD, but some patients may not respond adequately, necessitating adjunctive therapies. This study investigated the antimicrobial activity of diacetylcurcumin (DAC), a modified curcumin, against multispecies subgingival biofilm associated with periodontitis. Methods: The biofilm, containing 40 bacterial species, was cultured for seven days in the Calgary apparatus. Treatments with DAC (200 μg/mL), 0.12% chlorhexidine (CHX), and a vehicle (control) were applied twice daily for 1 min, starting on the third day. On the seventh day, biofilms were analyzed for metabolic activity (MA) and bacterial counts via DNA-DNA hybridization. DAC toxicity was tested on Galleria mellonella larvae. Results: DAC reduced biofilm metabolic activity by 51%, while CHX achieved 88% reduction compared to the vehicle (p < 0.05). DAC also significantly decreased counts of key periodontal pathogens, including P. gingivalis, T. forsythia, P. intermedia, and A. actinomycetemcomitans (p < 0.05). At the tested concentration, DAC showed no toxicity in larvae. Conclusions: These findings suggest that DAC effectively reduces biofilm activity and periodontal pathogen counts, presenting a promising adjunctive therapy for PD.

Chlorhexidine (CHX) and cetylpyridinium chloride (CPC) are commonly used as mouthwashes due to their antimicrobial effect. More recently, hyaluronic acid (HA) has also been associated to oral health products aiming to improve their anti-inflammatory and antimicrobial effects. This study aimed to evaluate the effect of three different CHX-based commercially available products on the subgingival microbial composition and metabolic activity using a multispecies biofilm model. A biofilm model composed of 33 bacterial species with 7 days of maturation on a Calgary plate device was used. The multispecies biofilm was treated with CHX 0.2% (positive control), CHX 0.2% + CPC (test 1), CHX 0.2% + HA 1% (test 2), and culture medium (negative control). The metabolic activity of the multispecies biofilm was measured using a spectrophotometric assay and the microbial composition by checkerboard DNA-DNA hybridization. The studied groups were compared using ANOVA and post hoc Bonferroni tests. The significance level was established at 5%. The CHX+CPC gel was more effective than the other treatments in reducing proportions of red complex species and increasing bacterial species associated with periodontal health (p<0.05). A reduction of approximately 54% was observed in the microbial metabolic activity of biofilms treated with CHX and CHX + CPC, and 26% in biofilms treated with CHX+HA. The CHX+CPC gel seems to have a superior antibacterial potential when compared to a gel containing CHX only, or CHX+HA, in an in vitro multispecies biofilm model.

The aim of this study was to evaluate the effect of the combination of neovestitol–vestitol (CNV) compounds obtained from Brazilian red propolis on the microbiological profile of a mature multispecies subgingival biofilm. The biofilm with 32 bacterial species associated with periodontitis was formed for seven days using a Calgary device. Treatment with CNV (1600, 800, 400, and 200 μg/mL), amoxicillin (54 μg/mL), and vehicle control was performed for 24 h on the last day of biofilm formation. Biofilm metabolic activity and DNA–DNA hybridization (checkerboard) assays were performed. The groups treated with CNV 1600 and amoxicillin reduced 25 and 13 species, respectively, compared to the control vehicle treatment (p ≤ 0.05); both reduced P. gingivalis, while only CNV reduced T. forsythia. When the data from the two treatments (CNV and AMOXI) were compared, a statistically significant difference was observed in 13 species, particularly members of Socransky’s orange complex. Our results showed that CNV at 1600 μg/mL showed the best results regarding the metabolic activity of mature biofilms and obtained a reduction in species associated with the disease, such as T. forsythia, showing a better reduction than amoxicillin. Therefore, CNV seems to be a promising alternative to eradicate biofilms and reduce their pathogenicity.

The control of infectious diseases caused by biofilms is a continuing challenge for researchers due to the complexity of their microbial structures and therapeutic implications. Photodynamic therapy as an adjunctive anti-infective treatment has been described as a possible valid approach but has not been tested in polymicrobial biofilm models. This study evaluated the effect of photodynamic therapy in vitro with methylene blue (MB) 0.01% and red LEDs (λ = 660 nm, power density ≈ 330 mW/cm², 2 mm distance from culture) on the metabolic activity and composition of a multispecies subgingival biofilm. Test Groups LED and MB + LED showed a more significant reduction in metabolic activity than the non-LED application group (~50 and 55%, respectively). Groups LED and MB equally affected (more than 80%) the total bacterial count in biofilms. No differences were noted in the bacterial biofilm composition between the groups. In vitro LED alone or the MB + LED combination reduced the metabolic activity of bacteria in polymicrobial biofilms and the total subgingival biofilm count.

Dehiscence in surgeries involving membranes often leads to bacterial contamination, hindering the healing process. This study assessed bacterial colonization on various membrane materials. Polydioxanone (PDO) membranes, with thicknesses of 0.5 mm and 1 mm, and a collagen membrane were examined. Packages containing polystyrene pins were crafted using these membranes, attached to 24-well plates, and exposed to oral bacteria from supra and subgingival biofilm. After a week’s anaerobic incubation, biofilm formation was evaluated using the DNA–DNA hybridization test. Statistical analysis employed the Kruskal–Wallis test with Dunn’s post hoc test. The biofilm on the polystyrene pins covered by the 0.5 mm PDO membrane showed a higher count of certain pathogens. The collagen membrane had a greater total biofilm count on its inner surface compared to both PDO membranes. The external collagen membrane face had a higher total biofilm count than the 0.5 mm PDO membrane. Furthermore, the 1 mm PDO membrane exhibited a greater count of specific pathogens than its 0.5 mm counterpart. In conclusion, the collagen membrane presented more biofilm and pathogens both internally and on its inner surface.

Bioactive materials were developed with the ability to release fluoride and provide some antimicrobial potential, to be widely used in dentistry today. However, few scientific studies have evaluated the antimicrobial activity of bioactive surface pre-reacted glass (S-PRG) coatings (PRG Barrier Coat, Shofu, Kyoto, Japan) on periodontopathogenic biofilms. This study evaluated the antibacterial activity of S-PRG fillers on the microbial profile of multispecies subgingival biofilms. A Calgary Biofilm Device (CBD) was used to grow a 33-species biofilm related to periodontitis for 7 days. The S-PRG coating was applied on CBD pins from the test group and photo-activated (PRG Barrier Coat, Shofu), while the control group received no coating. Seven days after treatment, the total bacterial counts, metabolic activity, and microbial profile of the biofilms were observed using a colorimetric assay and DNA–DNA hybridization. Statistical analyses were applied; namely, the Mann–Whitney, Kruskal–Wallis, and Dunn’s post hoc tests. The bacterial activity of the test group was reduced by 25.7% compared with that of the control group. A statistically significant reduction was observed for the counts of 15 species: A. naeslundii, A. odontolyticus, V. parvula, C. ochracea, C. sputigena, E. corrodens, C. gracilis, F. nucleatum polymorphum, F. nucleatum vincentii, F. periodonticum, P. intermedia, P. gingivalis, G. morbillorum, S. anginosus, and S. noxia (p ≤ 0.05). The bioactive coating containing S-PRG modified the composition of the subgingival biofilm in vitro, thereby decreasing colonization by pathogens.