''Streptococcus salivarius'' is a species of

spherical A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the ce ...

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

lactic acid bacteria Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped ( bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...

that is both catalase and

oxidase In biochemistry, an oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydro ...

negative. ''S. salivarius'' colonizes (usually in chains) the

oral cavity In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on t ...

and

upper respiratory tract The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to t ...

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 An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immune ...

, rarely finding its way into the bloodstream, where it has been implicated in cases of

sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...

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 growth medium is used that includes sucrose then ''S. salivarius'' is able to use the sucrose to produce a capsule around itself. However, if sucrose is replaced by

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

as on a GYC (glucose, yeast extract, calcium carbonate) plate, ''S. salivarius'' is unable to make a capsule from the 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 plat

Role as a probiotic

Some strains of ''S. salivarius'' are being trialed for their use as a

probiotic Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria- host ...

in the

prevention Prevention may refer to: Health and medicine * Preventive healthcare, measures to prevent diseases or injuries rather than curing them or treating their symptoms General safety * Crime prevention, the attempt to reduce deter crime and crim ...

of oral infections. Some strains of ''S. salivarius'' are found to produce BLIS (

Bacteriocin Bacteriocins are proteinaceous or peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally, and ec ...

-like Inhibitory Substances) which are

antimicrobial peptide Antimicrobial peptides (AMPs), also called host defence peptides (HDPs) are part of the innate immune response found among all classes of life. Fundamental differences exist between prokaryotic and eukaryotic cells that may represent targets for a ...

s. These peptides display interspecies inhibition, and inhibit ''

Streptococcus pyogenes ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus '' Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They ...

'' (which causes

strep throat Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by ''Streptococcus pyogenes'' a gram-positive, group A streptococcus. Common sympto ...

infections). Lozenges containing S. salivarius are marketed to support immunity against more virulent Streptococcus strains. People with this strain of naturally occurring ''S. salivarius'' on their tongue have been shown to have fewer Strep throat infections. This is also being investigated for its potential to prevent

rheumatic heart disease Rheumatic fever (RF) is an inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a streptococcal throat infection. Signs and symptoms include fever, multiple painful jo ...

which is also caused by ''S. pyogenes.''

Agglutination In linguistics, agglutination is a morphological process in which words are formed by stringing together morphemes, each of which corresponds to a single syntactic feature. Languages that use agglutination widely are called agglutinative lang ...

of ''Streptococcus salivarius'' is often used in the diagnosis of

atypical pneumonia Atypical pneumonia, also known as walking pneumonia, is any type of pneumonia not caused by one of the pathogens most commonly associated with the disease. Its clinical presentation contrasts to that of "typical" pneumonia. A variety of microorgan ...

caused by ''

Haemophilus influenzae ''Haemophilus influenzae'' (formerly called Pfeiffer's bacillus or ''Bacillus influenzae'') is a Gram-negative, non-motile, coccobacillary, facultatively anaerobic, capnophilic pathogenic bacterium of the family Pasteurellaceae. The bacter ...

Subspecies

''Streptococcus salivarius'' subsp. ''thermophilus'', also known as ''

Streptococcus thermophilus ''Streptococcus thermophilus'' also known as ''Streptococcus salivarius ''subsp.'' thermophilus'' is a gram-positive bacterium, and a fermentative facultative anaerobe, of the '' viridans'' group. It tests negative for cytochrome, oxidase, an ...

'', is a subspecies of ''S. salivarius''.

References

External links

''Streptococcus salivarius''

UniProt UniProt is a freely accessible database of protein sequence and functional information, many entries being derived from genome sequencing projects. It contains a large amount of information about the biological function of proteins derived from ...

Type strain of ''Streptococcus salivarius'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
Gram-positive bacteria Streptococcaceae Bacteria described in 1906 {{lactobacilli-stub

Role as a probiotic

Subspecies

References

Further reading

External links