Pigment Observed in Cultures of Hemolytic Streptococci Belonging to Lancefield Group A. ∗

Pigment production is not often observed in the growth of the hemolytic streptococcus. Durand and Giraud, 1 in a study of 124 cases of human streptococcus infection, reported the isolation of pigmented strains in 11 instances. Olivieri 2 reported the isolation of pigmented hemolytic streptococci from chronic pyelonephritis. Since these studies were made before the development of serological grouping, it is impossible to interpret the observations in terms of the newer classification. More recently, pigment has been observed in strains belonging to Lancefield's Group B, and occasionally to Lancefield's Group D. 3 As far as could be determined from the literature, the phenomenon of pigment production has not been described in strains belonging to Group A.

During an epidemiological study of hemolytic streptococcus infections involving several thousand cultures, pigmented colonies were observed on several occasions in the cultures of 3 patients. A fourth pigmented strain was observed from a case of scarlet fever in an Army camp. The data relating to these strains are summarized in Table I. All strains were classified as to group by the precipitation method of Lancefield, 4 and serological type was determined by the Griffith method of slide-agglutination. 5 Cross reactions occurred in these strains only as indicated in Table I.

The results of cultural studies on these strains are summarized in Table II. It seems that the environmental requirements for pigment production on artificial media closely parallel those of the pigmented Lancefield Group B strain included as a control. All media were observed at intervals of 24 hours through 14 days'incubation. Maximum pigment production was observed after 48 hours'incubation on 5.0% horse blood agar, or in buffered dextrose beef infusion broth.