Modulation of Biofilm Formation and Permeability in Streptococcus mutans during Exposure To Zinc Acetate.

The penetration of biofilms by antimicrobials is a potential limiting factor in biofilm control. This is relevant to oral health, as compounds that are used to control microbial growth and activities could also affect the permeability of dental plaque biofilm with secondary effects on biofilm tolerance. We investigated the effects of zinc salts on the permeability of Streptococcus mutans biofilms. Biofilms were grown with low concentrations of zinc acetate (ZA), and a transwell transportation assay was applied to test biofilm permeability in an apical-basolateral direction. Crystal violet assays and total viable counts were used to quantify the biofilm formation and viability, respectively, and short time frame diffusion rates within microcolonies were determined using spatial intensity distribution analysis (SpIDA). While the diffusion rates within biofilm microcolonies were not significantly altered, exposure to ZA significantly increased the overall permeability of S. mutans biofilms (P < 0.05) through decreased biofilm formation, particularly at concentrations above 0.3 mg/mL. Transport was significantly lower through biofilms grown in high sucrose conditions. IMPORTANCE Zinc salts are added to dentifrices to improve oral hygiene through the control of dental plaque. We describe a method for determining biofilm permeability and show a moderate inhibitory effect of zinc acetate on biofilm formation, and that this inhibitory effect is associated with increases in overall biofilm permeability.

Evaluation of Temporal Aggregation Processes Using Spatial Intensity Distribution Analysis.

Small proteinaceous oligomeric species contribute to the formation of larger aggregates, a phenomenon that is of direct relevance to the characterization of protein aggregation in biopharmaceuticals and understanding the underlying processes contributing to neurodegenerative diseases.The ability to monitor in situ oligomerization and aggregation processes renders imaging and image analysis an attractive approach for gaining a mechanistic insight into early processes contributing to the formation of larger aggregates in disease models and biologics. The combination of image analysis tools enables the detection of both oligomeric and larger aggregate subtype in contrast to conventional kinetic-based approaches that lack the ability to resolve dimers from monomeric moieties in samples containing mixed populations.In this chapter, we describe the process for confocal time series image acquisition for monitoring the in situ loss of monomers, and the subsequent analysis pipeline using spatial intensity distribution analysis (SpIDA) to evaluate oligomer content.

Antibacterial efficacy of a cetylpyridinium chloride-based mouthrinse against Fusobacterium nucleatum and in vitro plaques.

PURPOSE: To assess the antimicrobial effects of a fluoride-free and alcohol-free mouthrinse containing 0.075% CPC (test rinse, TR) compared with an otherwise-identical CPC-free control rinse (CR). METHODS: Activity against laboratory cultures of Fusobacterium nucleatum, a bacterium associated with gingival disease, was determined using viable counting following 30-second exposures to TR and CR. Effects against intact saliva-derived plaque biofilms were quantified using confocal microscopy coupled with three-dimensional image analyses (viability profiling). RESULTS: Short exposures to TR caused significant inactivation of F. nucleatum, as determined by viable counting (c. 3 log reduction compared to the control rinse, P < 0.05). Confocal microscopy revealed extensive inactivation of complex oral biofilms following treatment with TR; biofilms were significantly less viable than those exposed to CR and three-dimensional images revealed extensive zones of dead bacteria even within plaque depths. In conclusion, this investigation demonstrates that the CPC-containing mouthrinse has significant antibacterial efficacy against oral bacteria associated with gingival disease and significantly inactivated plaque biofilm in comparison to a relevant control.

Antibacterial and anti-biofilm activity of mouthrinses containing cetylpyridinium chloride and sodium fluoride.

BACKGROUND: Cetylpyridinium chloride (CPC) and sodium fluoride augment oral hygiene by inactivating bacteria and inhibiting enamel demineralisation, respectively. However, there are few reports in the literature documenting the antibacterial efficacy of their combined use in mouthrinses. We have used six experimental systems to compare the antibacterial effects of mouthrinses containing 0.075% CPC (test rinse, TR) or 0.075% CPC with sodium fluoride (test fluoride rinse, TFR). RESULTS: Effects against planktonic bacteria were determined using viable counting (for Streptococcus mutans and salivary bacteria), a redox dye (for Actinomyces viscosus and salivary bacteria) and viable counting (for ex vivo oral rinses). Effects against saliva-derived biofilms were quantified using confocal microscopy and differential viable counting. Inhibition of biofilm formation was evaluated by pre-treating hydroxyapatite coupons with mouthrinses prior to inoculation. Otherwise-identical controls without CPC (control rinse and control fluoride rinse, CR and CFR, respectively), were included throughout. Compared to the controls, TFR and TR demonstrated significant antimicrobial effects in the redox assays, by viable counts (>3 log reductions) and in oral rinse samples (>1.25 log reductions, p < 0.05). TFR and TR also significantly reduced the viability of oral biofilms. Pre-treatment of hydroxyapatite with TFR and TR significantly inhibited biofilm formation (>3 log difference, p < 0.05). Overall, there were no consistent differences in the activities of TR and TFR. CONCLUSIONS: Sodium fluoride did not influence the antibacterial and anti-biofilm potency of CPC-containing formulations, supporting the combined use of CPC and sodium fluoride in mouthrinses to control oral bacteria and protect tooth enamel.