Streptococcus vestibularis

Streptococcus vestibularis (S. vestibularis) is a species of Streptococcus. It is a commensal bacterium that can cause infections in people with weakened immune systems. 

 Classification 
S. vestibularis is one of the viridans streptococci. By comparing its DNA to others in the group, scientists identified S. vestibularis as a member of the salivarius group of streptococci. This group includes Streptococcus salivarius, Streptococcus thermophilus and Streptococcus vestibularis, which are genetically similar species of Streptococcus.

 Biology and ecology 
S. vestibularis was first isolated from the human mouth and was identified as a new species in 1988. S. vestibularis is considered a normal part of the mouth's 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 (.001mm). They are unable to move by themselves and do not produce spores.

S. 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 (an enzyme that catalyses the hydrolysis of urea) 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% (wt/vol) sodium chloride (NaCl) or 0.0004% (wt/vol) crystal violet.

 Symptoms 
S. vestibularis is classified as a level 2 biohazard in Canada and France and a level 1 biohazard in Germany. While research on the bacteria has been limited, some research points to it causing rejection in heart implants.  Additionally, significant amounts were found amongst children going through sepsis, though it wasn't determined to be the cause.

 Resistance 
S. vestibularis has been reported to exhibit the highest level of antibiotic resistance among the viridans group streptococci (VGS) species examined. 

In one study, only 39.7% of isolates in the Streptococcus mitis group were susceptible to penicillin, with complete and partial resistance observed in 39.4% and 20.9% of cases, respectively. Resistance to ampicillin was found to be similar to that of penicillin. Within this study, seven samples were identified specifically as S. vestibularis; among them, one sample was resistant to both penicillin and ampicillin, while two showed intermediate resistance. Additionally, S. vestibularis had the highest resistance to erythromycin, with 40.9% of isolates showing resistance.

References

Category:Bacteria