[Serotype and antibiotic susceptibilities of group A hemolytic streptococci isolated in Osaka, 1988-1989].

A total of 386 strains of Group A hemolytic Streptococci isolated from the patients in Osaka in 1988 and 1989 were type-classified by both T-agglutination and M-precipitin methods and were examined for drug-sensitivity. The results were summarized as follows. 1. From T-typing result, T-1 (28.2%) was revealed as the most dominant serotype in 1988, followed by T-4 (24.9%), and T-12 (23.2%), although not as much difference was found in the isolation rate among these three types. A similar tendency was observed in the results of 1989. The order was T-4 (30.3%), T-1 (24.8%), and T-12 (22.1%). 2. In the isolated Group A hemolytic Streptococci, 177 out of 241 strains (73.4%) in 1988 and 126 out of 145 strains (86.9%) in 1989 were M-typable with seven kinds of M-typing sera (Anti-M-1, 3, 4, 6, 12, 13, 18). The result of M-typing was similar to that of T-typing, because the coincidence rate between T and M types was very high among the most prevalent serotypes such as 1, 4, 6, and 12 (type-1: 98.1%, type-4:89.4%, type-6:91.7%, type-12:94.3%). 3. The number of antibiotic-resistant strains decreased. It was especially prominent in the resistant strains to erythromycin, lincomycin and chloramphenicol. While the incidence of tetracycline resistant strains in type-4, 11 and 13 remained at a high level, it decreased in type-12 and 1. All strains were sensitive to the beta-lactam antibiotics. 4. No resistant strains were detected to enoxacin (ENX) and ofloxacin (OFLX), new quinolone. MIC90 values of ENX and OFLX were 16 micrograms/ml and 2 micrograms/ml, respectively, although difference of MIC90 was observed among some strain types: MIC90 of ENX against type-6 strain was 8 times higher than that against type-12 strain.