Online Medical Dictionary and glossary with medical definitions, s listing.
Group A Streptococcus is defined as a gram-positive bacterial genus composed of Streptococcus pyogenes strains. Group A Streptococcus strains have a similar surface antigen recognized by specific laboratory tests, termed the Lancefield group A antigen. Lancefield groups (there are about 18 Lancefield groups) are composed of different Streptococcus species groups that have specific antigens and.
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