Antimicrobial effects of photodynamic therapy with Fotoenticine on Streptococcus mutans isolated from dental caries.

Photodynamic therapy (PDT) is a promising strategy to control cariogenic pathogens, such as Streptococcus mutans. Seeking to reach the total bacterial elimination from dental surfaces, novel photosensitizers have been investigated, such as Fotoenticine (FTC) derived from chlorin e6. The objective of this study was to investigate the photodynamic effects of FTC against several clinical strains of S. mutans. Clinical isolates were obtained from patients with active carious lesions, identified by molecular analysis and subjected to PDT using laser irradiation (660 nm and 39.5 J/cm2) in planktonic and biofilm stages. We identified 11 S. mutans strains from cervical, occlusal and proximal caries. PDT mediated by FTC has totally eliminated the S. mutans cells in planktonic growth for all analyzed strains. In biofilms, PDT with FTC reached statistically significant reductions compared with the non-treated control group, at 5.4, 5.5 and 6.5 Log10 (CFU/mL), respectively, for the strains from proximal, occlusal and cervical caries. The scanning electron microscopy evaluations confirmed that PDT mediated by FTC was able to disaggregate and kill the S. mutans cells adhered to enamel surface, suggesting its potential to disinfect the dental tissues.

Chitosan enhances the antimicrobial photodynamic inactivation mediated by Photoditazine® against Streptococcus mutans.

Chitosan (CS), a biopolymer with intrinsic antimicrobial activity, can increase antimicrobial photodynamic inactivation (aPDI). The aim of this study was to evaluate the capacity of CS to potentiate the efficacy of Photoditazine® (PDZ)-mediated aPDI of the cariogenic bacterium Streptococcus mutans. CS effectively augmented the effects of aPDI, with reductions of approximately 4.5 logs in both planktonic and biofilm states. The combined treatment was also capable of reducing the number of S. mutans cells and amount of extracellular matrix in biofilms formed on enamel surfaces, which were characterized using scanning electron microscopy analysis. Furthermore, CS increased the absorption of PDZ by S. mutans cells. The combination of CS with PDZ-mediated aPDI is hence a promising antimicrobial approach against S. mutans and may be useful to control dental caries.

Candida Biofilms: An Update on Developmental Mechanisms and Therapeutic Challenges.

Fungi of the genus Candida are important etiological agents of superficial and life-threatening infections in individuals with a compromised immune system. One of the main characteristics of Candida is its ability to form highly drug tolerance biofilms in the human host. Biofilms are a dynamic community of multiple cell types whose formation over time is orchestrated by a network of transcription regulators. In this brief review, we provide an update of the processes involved in biofilm formation by Candida spp. (formation, treatment, and control), as well as the transcriptional circuitry that regulates its development and interactions with other microorganisms. Candida albicans is known to build mixed species biofilms with other Candida species and with various other bacterial species in different host niches. Taken together, these properties play a key role in Candida pathogenesis. In addition, this review gathers recent studies with new insights and perspectives for the treatment and control of Candida biofilms.