AM-19226 is a pathogenic, non-O1/non-O139 serogroup strain of Vibrio cholerae that uses a Type 3 Secretion System (T3SS) mediated mechanism to colonize host tissues and disrupt homeostasis, causing cholera. Co-culturing the Caco2-BBE human intestinal epithelial cell line with AM-19226 in the presence of bile results in rapid mammalian cell death that requires a functional T3SS. We examined the role of bile, sought to identify the mechanism, and evaluated the contributions of T3SS translocated effectors in in vitro cell death.
View Article and Find Full Text PDFUnlabelled: The SpxA1 and SpxA2 (formerly SpxA and SpxB) transcriptional regulators of Streptococcus mutans are members of a highly conserved family of proteins found in Firmicutes, and they were previously shown to activate oxidative stress responses. In this study, we showed that SpxA1 exerts substantial positive regulatory influence over oxidative stress genes following exposure to H2O2, while SpxA2 appears to have a secondary regulatory role. In vitro transcription (IVT) assays using purified SpxA1 and/or SpxA2 showed that SpxA1 and, less often, SpxA2 directly activate transcription of some of the major oxidative stress genes.
View Article and Find Full Text PDFStreptococcus mutans is the etiological agent of dental caries and one of the many bacterial species implicated in infective endocarditis. The expression of the collagen-binding protein Cnm by S. mutans has been associated with extraoral infections, but its relevance for dental caries has only been theorized to date.
View Article and Find Full Text PDFStreptococcus mutans is often cited as the main bacterial pathogen in dental caries, particularly in early-childhood caries (ECC). S. mutans may not act alone; Candida albicans cells are frequently detected along with heavy infection by S.
View Article and Find Full Text PDFCranberry A-type proanthocyanidins (PACs) have been recognized for their inhibitory activity against bacterial adhesion and biofilm-derived infections. However, the precise identification of the specific classes of degree-of-polymerization (DP) conferring PACs bioactivity remains a major challenge owing to the complex chemistry of these flavonoids. In this study, chemically characterized cranberries were used in a multistep separation and structure-determination technique to isolate A-type PAC oligomers of defined DP.
View Article and Find Full Text PDFTrans-trans farnesol (tt-farnesol) is a bioactive sesquiterpene alcohol commonly found in propolis (a beehive product) and citrus fruits, which disrupts the ability of Streptococcus mutans (S. mutans) to form virulent biofilms. In this study, we investigated whether tt-farnesol affects cell-membrane function, acid production and/or acid tolerance by planktonic cells and biofilms of S.
View Article and Find Full Text PDFThe saliva proteome includes host defense factors and specific bacterial-binding proteins that modulate microbial growth and colonization of the tooth surface in the oral cavity. A multidimensional mass spectrometry approach identified the major host-derived salivary proteins that interacted with Streptococcus mutans (strain UA159), the primary microorganism associated with the pathogenesis of dental caries. Two abundant host proteins were found to tightly bind to S.
View Article and Find Full Text PDFBackground: The association of specific bioactive flavonoids and terpenoids with fluoride can modulate the development of cariogenic biofilms by simultaneously affecting the synthesis of exopolysaccharides (EPS) and acid production by Streptococcus mutans, which enhanced the cariostatic effectiveness of fluoride in vivo. In the present study, we further investigated whether the biological actions of combinations of myricetin (flavonoid), tt-farnesol (terpenoid) and fluoride can influence the expression of specific genes of S. mutans within biofilms and their structural organization using real-time PCR and confocal fluorescence microscopy.
View Article and Find Full Text PDFCranberry fruit is a rich source of polyphenols, and has shown biological activities against Streptococcus mutans. In the present study, we examined the influence of extracts of flavonols (FLAV), anthocyanins (A) and proanthocyanidins (PAC) from cranberry on virulence factors involved in Streptococcus mutans biofilm development and acidogenicity. PAC and FLAV, alone or in combination, inhibited the surface-adsorbed glucosyltransferases and F-ATPases activities, and the acid production by S.
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