Diagnostic methods begin at the bedside. There are certain clinical manifestations of infection by hemolytic streptococci which for all practical purposes settle the diagnosis. The most widely known of these are (1) scarlet fever and (2) erysipelas. Others which are almost as diagnostic are: (3) the fiery red throat, often with exudate, observed in older children; (4) visible cervical adenitis, and (5) a spontaneously discharging ear. These signs may represent infection by another microorganism, just as a scarlatinal rash may be caused on occasions by staphylococci, but the odds are strongly in favor of a streptococcic causation.
In cases of a less obvious variety of streptococcosis a history of recent occurrence of any of these manifestations in other members of the family is often helpful, especially if it is appreciated that streptococcic disease varies clinically within the family just as it does in unrelated patients. For example, in the case
BOISVERT PL. DIAGNOSIS OF STREPTOCOCCOSIS IN CHILDREN. Am J Dis Child. 1942;64(3):505-515. doi:10.1001/archpedi.1942.02010090107014