[Epidemiological survey of group A hemolytic streptococci isolated in Osaka during the 21-year period between 1967 and 1987. Part II. Antibiotic susceptibility].

During the 21-year period between 1967 and 1987, a total of 4678 strains of group A hemolytic streptococci isolated in Osaka were examined for drug sensitivity. The results were summarized as follows. 1. All strains were sensitive to the beta-lactam group of antibiotics (benzylpenicillin and cephaloridine). Resistant strains (M.I.C. greater than or equal to 25 micrograms/ml) to tetracycline (TC), chloramphenicol (CP) and erythromycin (EM) were isolated in this study period. The incidence of TC-resistant strains in the whole isolates has not much varied through the whole period, in spite of the variation among several T-type. But those of CP- and EM-resistant strains varied greatly by year. 2. Before 1971, a small number of resistant strain was found in 1969 and 1970. Since 1972, increase of such strains had been seen and the incidence of CP-resistant strains reached the highest peak (32.5%). It showed a gradual decrease since 1976 and was 1.1% in 1987. 3. None of EM-resistant strains was isolated before 1972. The incidence of EM-resistant strains exhibited a steep rise in percent since 1973 and reached the highest value showing a two-peak-pattern in 1975 (36.1%) and in 1980 (36.0%). After reaching its peak it decreased gradually and was 2.9% in 1987. 4. Remarkable increase of the multiple drug resistant strains began to be observed since 1972 to 1973, and mainly T-12 and T-4 showed EM. TC. CP- and TC. CP-resistance, respectively. The phenomenon of multiple drug-resistance culminated during 1975-1977, followed by gradual decrease thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)