Streptococcus salivarius

Streptococcus salivarius
Colony of Streptococcus salivarius on blood agar
Scientific classification
Kingdom: Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Species: S. salivarius
Binomial name
Streptococcus salivarius
Andrewes & Horder 1906
Synonyms

Streptococcus salivarius subsp. thermophilus Andrewes & Horder 1906

Streptococcus salivarius is a species of spherical, gram-positive bacteria that is both catalase and oxidase negative. S. salivarius colonizes (usually in chains) the mouth and upper respiratory tract of humans just a few hours after birth, making further exposure to the bacteria harmless in most circumstances. The bacteria is considered an opportunistic pathogen, rarely finding its way into the bloodstream, where it has been implicated in cases of sepsis in people with neutropenia,( a deficiency in white blood cells).

S. salivarius has distinct characteristics when exposed to different environmental nutrients. For example, in the laboratory, if a SYTA plate (Petri dish), is used, then S. salivarius is able to use the sucrose in the SYTA plate to produce a capsule around itself. However, if grown on a GYC (glucose, yeast extract,calcium carbonate) plate, with glucose, instead of sucrose, then S. salivarius is unable to make a capsule from glucose.

More importantly, in the laboratory, S. salivarius can show a distinct clearing on GYC plates. This is because S. salivarius can ferment the glucose yielding lactic acid. Next, the lactic acid actually reacts with the calcium carbonate in the GYC plate, resulting in zones of clearings on the plate.

Role as a probiotic

Some strains of S. salivarius are being trialed for their use as a probiotic in the prevention of oral infections. Some strains of S. salivarius are found to produce BLIS (Bacteriocin-like Inhibitory Substances) which is an antimicrobial peptide. This peptide displays interspecies inhibition, and inhibits Streptococcus pyogenes (which causes Strep throat infections). Lozenges containing S. salivarius are currently available as "K12 blis throat guard lozenges". These lozenges are marketed to support immunity against more virulent Streptococcus strains.[1] People with this strain of naturally occurring S. salivarius on their tongue have been shown to have fewer Strep throat infections.[2] This is also being investigated for its potential to prevent rheumatic heart disease which is also caused by S. pyogenes.

Agglutination of Streptococcus salivarius is often used in the diagnosis of atypical pneumonia caused by Haemophilus influenzae

Subspecies

Since 1995, the subspecies Streptococcus salivarius subs. thermophilus is a synonym of the species Streptococcus thermophilus.
So, the only subspecies Streptococcus salivarius subs. salivarius become a synonym of the species Streptococcus salivarius.

References

  1. ↑ http://blis.co.nz/blisk12-throatguarddaily-peppermintmint-60loz.html#.VgosNOfXenM
  2. ↑ Wescombe, P. A., N. C. K. Heng, et al. (2009). "Streptococcal bacteriocins and the case for Streptococcus salivarius as model oral probiotics." Future Microbiology 4(7): 819-835.

Further reading

External links


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