An outbreak of scarlet fever, which lasted from May 15 to June 3, 1972, occurred in a kindergarten in Tachikawa city in the west of greater Tokyo. Out of 224 attending children, 14 cases (6.1%) of scarlet fever, 6 (2.6%) of scarlet fever suspects, and 16 (7.5%) of acute pharyngitis were found in that outbreak. All scarlet fever cases were hospitalized in the isolation ward of pediatric deptartment of Tachikawa Hospital. The throat swab cultures performed on them were positive for beta hemolytic streptococci in 9 (64.3%). Six strains obtained from 5 cases were tested for grouping and typing by agglutination method. All of them belonged to Group A, of which three were. Type 12, one Type 1, and one, untypable.
On June 20, 197 children who were then attending the kindergarten were reexamined for hemolytic streptococci. Sixty seven (34.0%) were recognized as carrier of Group A, all of which were Type 12. The carriers from whom over 5 colonies of hemolytic streptococci per plate were isolated were administrated Bicillin. syrup 40, 000U/Kg/day for 8 days. The medication was proved effective for the germ eradication. Between these carriers and non-carriers, there found a significant difference in ASO titers; 18 of 56 carriers and 1 out of 21 non-carriers showed 250U or more.
In the meantime, we have been engaging the isolation of hemolytic streptococci in Tachikawa Hospital from December, 1970. It had been the tendency judged by various tests on 239 strains of beta streptococci isolated in the period up to December, 1972, that Type 12 was most prevalent and further a marked increase of the isolation of this type had been noticed in the second half of the year, 1972. Incidentally, an increase of acute glomerulonenpritis cases was seen in this city and its vicinity toward the end of that year. It was also a noticeable trend that, among 176 (73.6%) antibiotic resistant strains (to any or some of TC, EM, CP) out of those 239 strains tested, Type 12 was most predominant in number and the percentage to all Type 12 strains (145 strains) was 94.5%, the highest among all types, followed by Type 4 (83.3% of 24 strains). No strains of all tested were found resistant to penicillin-G or aminobenzylpenicillin. Save 4 strains, all were resistant to TC. The strains resistant not only to TC but also to EM were found in Type 12 in great number.
From these results, it is feared that such antibiotic resistant hemolytic streptococci will increase in number in notso distant future.