Streptococcus vestibularis
Streptococcus vestibularis is a species of Streptococcus. It is a commensal bacterium that can occasionally cause opportunistic infections within its human host. It is part of the viridans streptococci, and has been identified as a member of the salivarius group of streptococci through sequence homology of the 16S rRNA gene. This group includes Streptococcus salivarius, Streptococcus thermophilus and Streptococcus vestibularis, which are genetically similar species of Streptococcus.
Biology and ecology
Streptococcus vestibularis was first isolated from the vestibular mucosa of human oral cavities, and was identified as a new species in 1988. It is noted that “Streptococcus vestibularis is a normal inhabitant of vestibules of the human oral cavity”, therefore forming part of the oral microbiome. Streptococcus vestibularis cells are gram-positive and cocci in shape. They are catalase-negative as they do not have the enzyme catalase, which protects catalase-positive bacteria from hydrogen peroxide by converting it into hydrogen and oxygen. They grow in chains and have a diameter of approximately 1 μm. They are non-motile and non-spore forming.Streptococcus vestibularis produces acid from N-acetyl glucosamine, arbutin, fructose, galactose, glucose, lactose, maltose, mannose, salicin, and sucrose, although it does not produce extracellular glucan or fructan from sucrose. It also produces urease and hydrogen peroxide. It is unable to grow in conditions of 10 °C or 45 °C, whilst colonies can grow anaerobically at 37 °C. Also, this bacterium is unable to grow when in the presence of 4% sodium chloride or 0.0004% crystal violet.