Official websites use. Share sensitive information only on official, secure websites. This article is made available via the PMC Open Access Subset for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. The streptococci are a large heterogeneous group of gram-positive spherically shaped bacteria widely distributed in nature.
They include some of the most important agents of human disease as well as members of the normal human flora. Some streptococci have been associated mainly with disease in animals, while others have been domesticated and used for the culture of buttermilk, yogurt, and certain cheeses. These organisms are not generally part of the normal flora but cause acute, often severe, infections in normal hosts.
Second are the more diverse enteric and oral streptococci, which are nearly always part of the normal flora and which are more frequently associated with opportunistic infections.
Measured in terms of mortality, morbidity, and economic costs, five streptococcal species are of major importance in human disease.
Their nonsuppurative sequelae include acute rheumatic fever and acute glomerulonephritis. A detailed account of the pneumococcus may be found in Chapter Enterococcus is now a separate genus but will be considered an honorary Streptococcus in this chapter because of its similarities to enteric streptococci.
