Phylum Firmicutes, Class Bacilli, Order Lactobacillales, Family Streptococcaceae, Genus Streptococcus, Streptococcus intermedius
Formerly was considered a later heterotypic synonym of Streptococcus anginosus.
Usually ungroupable, but some strains may react with Lancefield group F & C antisera.
Gram-positive, 0.5-1.0 μm in diameter, coccoid cells, grouped in short chains.
Colonies on blood agar are 0.5-2.0 mm in diameter, white, translucent or matte,
convex and entire. On blood agar colonies are non-hemolytic or surrounded by zones
of alpha-hemolysis, occasionally beta-hemolytic. Always is beta-hemolytic on human
blood agar. Facultatively anaerobic. Growth is reduced aerobically, but enhanced by
incubation in 5% CO2-supplemented atmosphere.
Habitats are the human oral cavity and upper respiratory tract. It has been reported to occur in feces.
Isolated from human purulent infections, liver and brain abscesses.
- Robert A. Whiley and Jeremy M. Hardie, 2009. Genus I. Streptococcus Rosenbach 1884, 22AL. In: (Eds.) P.D. Vos, G. Garrity, D.
Jones, N.R. Krieg, W. Ludwig, F.A. Rainey, K.-H. Schleifer, W.B. Whitman. Bergey’s Manual of Systematic Bacteriology, Volume 3:
The Firmicutes, Springer, 655-711.
- Robert A. Whiley and David Beighton. Emended Descriptions and Recognition of Streptococcus constellatus, Streptococcus
intermedius, and Streptococcus anginosus as Distinct Species. Int J Syst Bacteriol January 1991 41:1-5.
Positive results for alkaline phosphatase, arginine hydrolysis, esculin hydrolysis, beta-fucosidase, beta-galactosidase,
alpha-glucosidase, beta-N-acetylgalactosaminidase, beta-N-acetylglucosaminidase, hyaluronidase, leucine arylamidase,
neuraminidase, Voges-Proskauer reaction, acid production from: amygdalin (most strains), cellobiose (most strains), glucose,
lactose, maltose, salicin (most strains), sucrose & trehalose.
Negative results for catalase, alpha-galactosidase, beta-glucuronidase, hippurate hydrolysis, hydrogen peroxide production,
pyrrolidonyl arylamidase, urease, acid production from: arabinose, glycerol, glycogen, inulin, ribose & sorbitol. A few produce acid
from mannitol, melibiose, raffinose & sorbitol.
Variable results for beta-glucosidase.
(c) Costin Stoica