The Serological Identity of a Yellow-Pigmented Streptococcus

SUMMARY: A yellow-pigmented Streptococcus was isolated from certain dairy cows. The three strains examined were closely related to Strep. faecalis but differed from it in fermenting raffinose. The organism produced a tyrosine decarboxylase. Sero-logically the organism belonged to Lancefield group D, Sharpe type 10. The literature contains many references to streptococci which produce pigment under anaerobic, or semi-anaerobic conditions, for example, in deep agar or broth cultures (Durand & Giraud, 1923; Lancefield, 1984; Plummer, 1941). The Streptococcus reported here produced pigment on the surface of aerobic plates. It was isolated three times from the teats of one cow which was being used in an experiment a t the Institute by my colleague, Mr F. K. Neave, on the preven-tion of the spread of Strep. agalactiae by means of nisin. It was not isolated from any of sixty other cows in the Institute herd. It was also isolated twice from the hands of the milker concerned. When first noticed it was in almost pure culture on the plate and may have been overlooked earlier. A year later a similar organism was isolated from another herd in which no antibiotics had been used. Three strains, two isolated from the Institute’s herd and one from the other herd, have been identified biochemically and serologically as belonging to group D