Group Q streptococci. I. Ecology, serology, physiology, and relationship to established enterococci.

The group Q streptococci possess unique serological and physiological characteristics which differentiate them from established enterococci. The group Q antigen was not demonstrable in all strains; however, all possessed the group D antigen. All group Q strains were physiologically similar regardless of whether or not they possessed the group Q antigen. These strains differed from the established enterococcal species, as they neither hydrolyzed arginine nor initiated growth in 1.0% methylene blue-milk. They also differed radically in the fermentation of various carbohydrates, especially the polyhydric sugar alcohols. The results indicate that the group Q streptococci constitute a unique taxonomic entity; the species designation Streptococcus avium sp. n. is suggested, owing to their characteristic occurrence in chicken fecal specimens.