STREPTOCOCCAL BACTERIA - A genus of bacteria that are gram positive cocci, often occurring in chains of varying length. Some pathogenic (disease causing) species produce exotoxins (toxic substances). In man, streptococcal species are responsible for numerous infections such as scarlet fever, tonsillitis, erysipelas (skin infection), endocarditis, rheumatic fever, glomerulonephritis, impetigo, pneumonia, meningitis, lymphadenitis, and wound infections.