Lancefield grouping of streptococci

Streptococci are sometimes classified in so-called Lancefield groups after the American microbiologist Rebecca Lancefield (1895 - 1981), who developed a system for serological classification based on the carbohydrate composition of the cell wall. The different groups are called Lancefield groups A to V (except I and J). There is also a group NG (= non-groupable).