Streptococci are gram-positive aerobic organisms that cause many disorders, including pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis. Symptoms vary with the organ infected. Sequelae of infections due to group A beta-hemolytic streptococci may include rheumatic fever and glomerulonephritis.Streptococcus is a genus of Gram-positive coccus (plural cocci) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Firmicutes. Cell division in streptococci occurs along a single axis, so as they grow, they tend to form pairs or chains that may appear bent or twisted. (Contrast with that of staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells.)The term was coined in 1877 by Viennese surgeon Albert Theodor Billroth (1829–1894) by combining the prefix "strepto-" (from Ancient Greek: στρεπτÏŒς, romanized: streptós, lit. 'easily twisted, pliant', together with the suffix "-coccus" (from Modern Latin: coccus, from Ancient Greek: κÏŒκκος, romanized: kókkos, lit. 'grain, seed, berry'Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes (capable of growth both aerobically and anaerobically).In 1984, many bacteria formerly grouped in the genus Streptococcus were separated out into the genera Enterococcus and Lactococcus.Currently, over 50 species are recognised in this genus. This genus has been found to be part of the salivary microbiome.