A previous study1 of hemolytic streptococci isolated from pharyngeal cultures of apparently healthy infants and young children showed that certain strains produced a skin reactive substance which was neutralized by convalescent scarlet fever serum. This was apparently identical with that formed by strains of hemolytic streptococci of scarlatinal origin. A similar study of organisms recovered from acute infections of the ear and mastoid in sick infants has been made.
The organisms were isolated on rabbit blood agar from patients under 2 years of age in the St. Louis Children's Hospital. All cultures were obtained from swabs which had received purulent material from the paracentesis knife just after myringotomy for acute otitis media, or that taken from the mastoid antrum at operation. In order to illustrate the relative prevalence of hemolytic streptococci in such infections of infants, 100 consecutive cultures from different infants have been tabulated in table 1. These