Occurrence of Streptococcus milleri among beta-hemolytic streptococci isolated from clinical specimens

A total of 256 beta-hemolytic streptococcal isolates were subjected to serological and physiological tests to identify those which could be classified as Streptococcus milleri. S. milleri accounted for 75% of 70 group C isolates, 15% of 69 group G isolates, 75% of 16 nongroupable isolates, and 100% of 20 group F isolates examined. No S. milleri isolates were encountered among the 90 group A streptococci studied. Of the 95 beta-hemolytic S. milleri isolates examined, 81% were recovered from respiratory specimens.