VicRK and CovR polymorphisms in strains associated with cardiovascular infections.

, a common species of the oral microbiome, expresses virulence genes promoting cariogenic dental biofilms, persistence in the bloodstream and cardiovascular infections. Virulence gene expression is variable among strains and controlled by the transcription regulatory systems VicRK and CovR. This study investigates polymorphisms in the and loci in strains isolated from the oral cavity or from the bloodstream, which were shown to differ in expression of , and downstream genes.

Antibacterial efficacy of non-thermal atmospheric plasma against Streptococcus mutans biofilm grown on the surfaces of restorative resin composites.

The aim of this study was to evaluate the antimicrobial efficacy of non-thermal atmospheric plasma (NTAP) against Streptococcus mutans biofilms. Resin discs were fabricated, wet-polished, UV sterilized, and immersed in water for monomer extraction (37 °C, 24 h). Biofilms of bioluminescent S.

is a target of the two-component systems VicRK and CovR required for systemic virulence of .

, a cariogenic species, is often associated with cardiovascular infections. Systemic virulence of specific serotypes has been associated with the expression of the collagen- and laminin-binding protein Cnm, which is transcriptionally regulated by VicRK and CovR. In this study, we characterized a VicRK- and CovR-regulated gene, , coding for a conserved endopeptidase.

PcsB Expression Diversity Influences on Phenotypes Associated With Host Persistence and Virulence.

is an abundant member of the commensal microbiota of the oral cavity and pharynx, which has the potential to promote systemic infections. By analyzing a collection of strains isolated from the oral cavity at commensal states or from systemic infections (blood strains), we established that ubiquitously express the surface immunodominant protein, PcsB (also called GbpB), required for binding to sucrose-derived exopolysaccharides (EPS). Immuno dot blot assays with anti-PcsB antibodies and RT-qPCR transcription analyses revealed strain-specific profiles of PcsB production associated with diversity in transcriptional activities.

Oral streptococci show diversity in resistance to complement immunity.

Purpose: Mechanisms underlying systemic infections by oral species of Mitis (Streptococcus mitis, Streptococcus oralis) and Sanguinis (Streptococcus gordonii, Streptococcus sanguinis) commensal streptococci are poorly understood. This study investigates profiles of susceptibility to complement-mediated host immunity in representative strains of these four species, which were isolated from oral sites or from the bloodstream.

Methodology: Deposition of complement opsonins (C3b/iC3b), and surface binding to C-reactive protein (CRP) and to IgG antibodies were quantified by flow cytometry in 34 strains treated with human serum (HS), and compared to rates of opsonophagocytosis by human PMN mediated by complement (CR1/3) and/or IgG Fc (FcγRII/III) receptors.

CovR and VicRKX Regulate Transcription of the Collagen Binding Protein Cnm of Streptococcus mutans.

Cnm is a surface-associated protein present in a subset of strains that mediates binding to extracellular matrices, intracellular invasion, and virulence. Here, we showed that transcription is controlled by the global regulators CovR and VicRKX. analysis identified multiple putative CovR- and VicR-binding motifs in the regulatory region of as well as in the downstream gene , which is associated with the posttranslational modification of Cnm.

Novel Two-Component System of Streptococcus sanguinis Affecting Functions Associated with Viability in Saliva and Biofilm Formation.

is a pioneer species of teeth and a common opportunistic pathogen of infective endocarditis. In this study, we identified a two-component system, SptRS (SptRS ), affecting survival in saliva and biofilm formation. Isogenic mutants of (SKsptR) and (SKsptS) showed reduced cell counts in assays of viability in saliva compared to those of parent strain SK36 and complemented mutants.

The two-component system VicRK regulates functions associated with Streptococcus mutans resistance to complement immunity.

Streptococcus mutans, a dental caries pathogen, can promote systemic infections upon reaching the bloodstream. The two-component system (TCS) VicRK of S. mutans regulates the synthesis of and interaction with sucrose-derived exopolysaccharides (EPS), processes associated with oral and systemic virulence.

Oral cavities of healthy infants harbour high proportions of Streptococcus salivarius strains with phenotypic and genotypic resistance to multiple classes of antibiotics.

Emerging antibiotic resistance in the oropharyngeal microbiota, of which Streptococcus salivarius is a prominent species, represents a challenge for treating paediatric populations. In this study, we investigated the role of Streptococcussalivarius as a reservoir for antibiotic resistance genes (ARG) in the oral microbiota by analysing 95 Streptococcussalivarius isolates from 22 healthy infants (2-16 months of age). MICs of penicillin G, amoxicillin, erythromycin, tetracycline, doxycycline and streptomycin were determined.

CovR Regulates Streptococcus mutans Susceptibility To Complement Immunity and Survival in Blood.

Streptococcus mutans, a major pathogen of dental caries, may promote systemic infections after accessing the bloodstream from oral niches. In this study, we investigate pathways of complement immunity against S. mutans and show that the orphan regulator CovR (CovR) modulates susceptibility to complement opsonization and survival in blood.

Two-component system VicRK regulates functions associated with establishment of Streptococcus sanguinis in biofilms.

Streptococcus sanguinis is a commensal pioneer colonizer of teeth and an opportunistic pathogen of infectious endocarditis. The establishment of S. sanguinis in host sites likely requires dynamic fitting of the cell wall in response to local stimuli.

Multiple-locus variable-number tandem-repeat analysis for clonal identification of Vibrio parahaemolyticus isolates by using capillary electrophoresis.

Epidemics of Vibrio parahaemolyticus in Chile have occurred since 1998. Direct genome restriction enzyme analysis (DGREA) using conventional gel electrophoresis permitted discrimination of different V. parahaemolyticus isolates obtained from these outbreaks and showed that this species consists of a highly diverse population.