Antigen analysis of group A streptococcus strain, "Matsuyama 2166", which had been typed as T12-28 (by the T-agglutination method), MNT (nontypeable by the M-precipitation method) using conventional typing sera was examined by the precipitation and precipitation absorption technique. The prevalence of group A streptococci, typed under the name "Matsuyama 2166" was also investigated. The results were as follows: 1) The strain "Matsuyama 2166" is OF (Opacity Factor) (+) and its serological components consist of M "Matsuyama 2166" antigen, which is unique in our collection of M-types, and T28 antigen as a major antigen along with T12 as a minor. 2) Out of the group A streptococci typed as MNT, 96.6% of the streptococci were types as T12-28 and 96.5% of T28 by conventional typing sera were strains to be typed as M "Matsuyama 2166" using the newly prepared M "Matsuyama 2166" typing serum, suggesting the great advantage to M-typing rate of T28 strains. 3) Group A streptococcus M "Matsuyama 2166" was also found in isolates from Thailand or Malaysia. It is interesting that T-types found in those isolates seems to be a little different from the T-types isolated in Japan. These results showed that there was the difficult problem when we did the speculation of M-type from the result of T-type.
A total of 44 patients suspected of streptococcal infections were studied in outpatient clinics in Tokyo during the one year from December 1988 to December 1989. Employing bacteriological culturing and serodiagnosis, the following results were obtained. 1) There were 9 cases of impetigo and 15 cases of erysipelas with typical clinical manifestations and age distributions. 2) It seemed that some of the skin infections were caused by group A streptococci whose M-types were different from those of upper respiratory infections typically occurring in Japan. 3) The type distribution of group A streptococci found were quite similar to those isolated in Thailand or Malaysia. 4) There were found group A streptococci exhibiting unique combinations of T- and M-types, such as T11 and M9, T11 and M62 or T13-49 and MOD8 (Provisional type). 5) As for serodiagnostic method, ADNB (anti-deoxyribonuclease B) titer reflected infection by group A streptococcus only, while ASK (anti-streptokinase) and ASO (anti-streptolysin O) reflected not only group A streptococcal infections but group G infections as well.