The ''Streptococcus anginosus'' group (SAG), also known as the anginosus group streptococci (AGS) or the milleri group streptococci (MGS), are a group of several
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
streptococci
''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...
with clinical similarities. The group is named after a principal member species, ''
Streptococcus anginosus
''Streptococcus anginosus'' is a species of ''Streptococcus
''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria) ...
''. The older name ''Streptococcus milleri'' (as well as ''Streptococcus milleri'' group, SMG) is now pseudotaxonomic, as the idea that these streptococci constituted a single species was incorrect. The anginosus group streptococci are members of the
viridans streptococci
The viridans streptococci are a large group of commensal streptococcal Gram-positive bacteria species that are α-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "vĭrĭdis", green), although so ...
group.
They have been implicated as etiologic agents in a variety of serious purulent infections, but because of their heterogeneous characteristics, these organisms may be unrecognized or misidentified by clinical laboratorians.
The unique characteristic of them from other pathogenic streptococci, such as ''S. pyogenes'' and ''S. agalactiae'', is their ability to cause abscesses.
Species
Members include:
* ''
Streptococcus anginosus
''Streptococcus anginosus'' is a species of ''Streptococcus
''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria) ...
''
* ''
Streptococcus constellatus
''Streptococcus constellatus'' is a species of ''Streptococcus'' that is part of the normal flora in the oral cavity, urogenital region, and intestinal tract. However, it can frequently cause purulent infections in other parts of the body. DNA ho ...
''
**S. constellatus subsp. constellatus
**S. constellatus subsp. pharyngis
* ''
Streptococcus intermedius
''Streptococcus intermedius'' is an aerotolerant anaerobic commensal bacterium and a member of the ''Streptococcus anginosus'' group. The ''S. anginosus'' group, occasionally termed “''Streptococcus milleri'' group” (SMG) display hemolytic a ...
''
Nomenclature
These nonhemolytic
viridans streptococci
The viridans streptococci are a large group of commensal streptococcal Gram-positive bacteria species that are α-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "vĭrĭdis", green), although so ...
were first described by Guthof in 1956 after he isolated them from
dental abscess
A dental abscess is a localized collection of pus associated with a tooth. The most common type of dental abscess is a periapical abscess, and the second most common is a periodontal abscess. In a periapical abscess, usually the origin is a bac ...
es. He named these organisms ''Streptococcus milleri'' in honor of the microbiologist
W. D. Miller.
Occurrence
The organisms were subsequently recognized as normal flora of the human oral cavity and gastrointestinal tract with the ability to cause abscesses and systemic infections.
References
External links
Streptococcaceae
Species groups
{{lactobacilli-stub