The nature of the opaque colony variation in group A streptococci

Abstract

Opaque colonies of group A streptococci, detected on clear agar plates with obliquely transmitted light, are composed of extremely long chains of cocci. The mucopeptide layer of the cell-wall is involved in the formation of enhanced intercellular bridges. It is suggested that this exaggerated chaining results in an altered growth pattern which gives the appearance of granular opacity to surface colonies.