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Chains of S. pyogenes bacteria (orange) at 900× magnification Gram stain of Streptococcus pyogenes. Unlike most bacterial pathogens, S. pyogenes only infects humans. Thus, zoonotic transmission from an animal (or animal products) to a human is rare. [8] S. pyogenes typically colonizes the throat, genital mucosa, rectum, and skin. Of healthy ...
Most Streptococcus genomes are 1.8 to 2.3 Mb in size and encode 1,700 to 2,300 proteins. Some important genomes are listed in the table. [33] The four species shown in the table (S. pyogenes, S. agalactiae, S. pneumoniae, and S. mutans) have an average pairwise protein sequence identity of about 70%. [33]
Coccoid bacteria often occur in characteristic arrangements and these forms have specific names as well; [8] listed here are the basic forms as well as representative bacterial genera: [3] Diplococci are pairs of cocci. Streptococci are chains of cocci such as Streptococcus pyogenes.
Group A streptococcal infections are a number of infections with Streptococcus pyogenes, a group A streptococcus (GAS). [1] S. pyogenes is a species of beta-hemolytic Gram-positive bacteria that is responsible for a wide range of infections that are mostly common and fairly mild. If the bacteria enters the bloodstream, the infection can become ...
Hemolyses of Streptococcus spp. (left) α-hemolysis (S. mitis); (middle) β-hemolysis (S. pyogenes); (right) γ-hemolysis (non-hemolytic, S. salivarius) Hemolysis is the breakdown of red blood cells. The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms.
Though there are many groups of streptococci, the principal organisms that are known to cause human disease belong to group A (Streptococcus pyogenes), group B (Streptococcus agalactiae), group C/G (Streptococcus dysgalactiae) both members of group D (Streptococcus gallolyticus and Streptococcus infantarius, both members of the Streptococcus ...
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 some species in this group are actually γ-hemolytic, meaning they produce no change on blood agar. [1]
Enterococcus faecalis – formerly classified as part of the group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans. [ 1 ] [ 2 ] Like other species in the genus Enterococcus , E. faecalis is found in healthy humans and can be used as a probiotic.