Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (AI-2), synthesized by LuxS, that plays an important role in expression of virulence factors, in intra- but also in interspecies communication. The aim of this study was to investigate the role of AI-2 based signaling in the interactions between C. albicans and A. actinomycetemcomitans. A. actinomycetemcomitans adhered to C. albicans and inhibited biofilm formation by means of a molecule that was secreted during growth. C. albicans biofilm formation increased significantly when co-cultured with A. actinomycetemcomitans luxS, lacking AI-2 production. Addition of wild-type-derived spent medium or synthetic AI-2 to spent medium of the luxS strain, restored inhibition of C. albicans biofilm formation to wild-type levels. Addition of synthetic AI-2 significantly inhibited hypha formation of C. albicans possibly explaining the inhibition of biofilm formation. AI-2 of A. actinomycetemcomitans is synthesized by LuxS, accumulates during growth and inhibits C. albicans hypha- and biofilm formation. Identifying the molecular mechanisms underlying the interaction between bacteria and fungi may provide important insight into the balance within complex oral microbial communities.

Campylobacter jejuni is a common cause of bacterial enteritis. The surface capsular polysaccharides are important for this bacterium to survive in the environment, but little is known about their involvement in bacterium-host interactions. This study showed that the C. jejuni capsular polysaccharides play an important role in adherence to and invasion of human embryonic epithelial cells. However, no significant role of capsular polysaccharides was shown in colonization of the chicken gut.

Objective Chitosan nanoparticle (nanochitosan) has a broad antimicrobial spectrum against diverse pathogenic microorganisms. However, its effect on dental caries-associated microorganisms, such as Streptococcus mutans and Candida albicans is yet to be explored. These microorganisms are known for causing early childhood caries. Therefore, this study was aimed at investigating nanochitosan inhibition capacity against dual-species biofilms of S. mutans and C. albicans. In this study, nanochitosan antimicrobial activity is reported against mono and dual biofilm species of S. mutans and/or C. albicans at 3 and 18 h incubation time. Nanochitosan inhibition capacity was observed through biofilm mass quantity and cell viability. Results The present study successfully synthesized nanochitosan with average diameter of approximately 20–30 nm, and also established dual-species biofilms of S. mutans and C. albicans in vitro. With nanochitosan treatment, the cell viability of both microorganisms significantly decreased with the increasing concentration of nanochitosan. There was no significant decrease in biofilm mass both in the dual and single-species biofilms after 3 h of incubation. However, greater inhibition of biofilm was observed at 18 h incubation.

Highlights Chitosan hybridized with titanium dioxide nanoparticles improves its bone regeneration capability. Nano titanium dioxide addition to the matrix of chitosan sponges was done successfully, as depicted from an even distribution of nano titanium dioxide on the surface of the sponges. Chitosan – nanoTiO 2 scaffold results in significantly improved sponge robustness, biomineralization, and bone regeneration capability, as indicated by DMP1 and OCN gene upregulation in chitosan-50% nanoTiO 2 sample.

The aim of this study was to analyze the synergistic Background: relationship between and in Candida albicans Streptococcus mutans children with early childhood caries (ECC) experience.Dental plaque and unstimulated saliva samples were taken from Methods: 30 subjects aged 3-5 years old, half with (n=15, dmft > 4) and half without (n=15) ECC. The abundance of and and relative to C. albicans S. mutans total bacteria load were quantify by real-time PCR (qPCR). This method was also employed to investigate the mRNA expression of glycosyltransferase ( ) gene in dental plaque. Student's t-test and gtfB Pearson's correlation were used to perform statistical analysis.Within the ECC group, the quantity of both microorganisms were Results: higher in the saliva than in dental plaque. The ratio of to total C. albicans bacteria was higher in saliva than in plaque samples (p < 0.05). We observed the opposite for (p < 0.05). The different value of S. mutans C. and in saliva was positively correlated, and negatively albicans S. mutans correlated in dental plaque. Transcription level of showed a S. mutans gtfB positive correlation with concentration in dental plaque. C. albicans has a positive correlation with cariogenic traits of Conclusion: C. albicans in ECC-related biofilm of young children. S. mutans