In the original report1 on Streptococcus epidemicus as the cause of septic sore throat in a milk borne epidemic, it was noted that on blood agar the colonies of this streptococcus were more moist, often mucoid and somewhat less hemolytic than those of ordinary hemolytic streptococci. For purposes of differentiation, these properties together with other features were emphasized by Brown, Frost and Shaw2 and by Frost, Gumm and Thomas3 in the isolation and identification of Streptococcus epidemicus from milk.
In a study of hemolytic streptococci from the throats and ears of patients with epidemic septic sore throat at Baraboo, Wis., these characteristics were noted on ordinary blood agar. On slants of meat infusion agar the colonies were slightly larger than those of ordinary streptococci and were distinctly more moist and ameboid. It was noted that these differences on ordinary blood agar, however, while constant, might be overlooked
Pilot I, Hallman B, Davis DJ. A CULTURE MEDIUM FOR THE ISOLATION OF STREPTOCOCCUS EPIDEMICUS OF SEPTIC SORE THROAT. JAMA. 1930;95(4):264-265. doi:10.1001/jama.1930.27210040001009