Serological properties of Abiotrophia and Granulicatella species (nutritionally variant streptococci)

Serological variations were examined among 12 type or reference strains and 91 oral isolates of vitamin B6-dependent Abiotrophia and Granulicatella sp p, Rabbits were immunized with whole cells of 12 selected strains and 10 ty ping antisera were obtained, which were unreactive with the Lancefield grou p A to G antigen preparations, The reactivity of the antisera and autoclave d cell surface antigen extracts was tested by double diffusion in agar gel and a capillary precipitin test. These typing antisera categorized all Abio trophia defectiva strains, all except one Granulicatella elegans strain, th ree-quarters of the Granulicatella adiacens, and half of the Granulicatella paraadiacens into 8 serotypes and 2 subserotypes, The Granulicatella balae nopterae type strain was unserotypable. All A. defectiva strains were serot ype I, some of which were divided into subserotype I-1 and/or I-5, The G, a diacens strains generally belonged to serotype II or III, and the G, paraad iacens strains to serotype IV, V or VI, All G, adiacens or G, paraadiacens serotype II strains were also subserotype 1-5, The G, elegans strains were serotype VII or VIII, These Abiotrophin and Granulicatella serotypes were u ndetectable among 33 strains of the other 11 species including the bacterio lytic enzyme-producing but vitamin B6-independent strains of Streptococcus, Enterococcus, Dolosigranulum and Aerococcus, The proposed serotyping syste m for Abiotrophia and Granulicatella spp, would be helpful in the identific ation and classification of these unique coccal isolates in ecological and epidemiological studies.