Prevalence and persistence of certain serologic types of Streptococcus pyogenes in metropolitan Tokyo

M-typing was conducted for Streptococcus pyogenes strains isolated within 1 week of admission from patients admitted to the Tokyo Metropolitan Toshima Hospital for scarlet fever in the 23-year period between 1956 and 1978. M12 was detected in the largest number of patients, followed by M6, M4, M3, and M1. T-typing was also conducted for Streptococcus pyogenes strains isolated from healthy schoolchildren in three different parts of the 20-year period between 1977 and 1998. T12 was detected in the largest number of children, followed by T28, T1, T4, and T6. These results suggested that strains of similar types are prevalent in scarlet fever patients and healthy carriers, that these strains become prevalent at intervals of several years, and that they are detected every year, albeit in a small number of persons, indicating that they are endemic. Isolated strains were typed by M-typing and T-typing. The results of typing were identical in more than 90% of cases. Comparison of major Streptococcus pyogenes strains isolated in Tokyo and three other major cities abroad showed that M12 was detected in the largest number of persons in Tokyo and New York and that major types were similar in the four cities.