serogroup /sēr′o-gro̅o̅p/ , 1. a group of bacteria containing a common antigen, sometimes including more than one serotype, species, or genus. This is an unofficial designation, used in the classification of certain genera of bacteria, such as Leptospira, Salmonella, Shigella, and Streptococcus. 2. a group of viral species that are closely related antigenically.
