| 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 |
|
Streptococcus salivarius is a species of spherical, Gram-positive bacteria which colonize the mouth and upper respiratory tract of humans a few hours after birth, making further exposure to the bacteria harmless. The bacteria is considered an opportunistic pathogen, rarely finding its way into the bloodstream, where it has been implicated in septicemia cases in people with neutropenia.
S. salivarius has distinct characteristics when exposed to different environmental nutrients. For example, in the laboratory, if a SYTA plate 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 GYC plate, with no sucrose, instead only glucose, then S. salivarius is not able 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.[1]
Agglutination of Streptococcus salivarius is often used in the diagnosis of atypical pneumonia caused by Haemophilus influenzae.