No abstract

During the 20-year period between 1979-1998, a total of 4,176 strains of hemolytic streptococci have been isolated from 20,118 healthy primary school children and little children in Tokyo Metropolitan (Tokubetsuku, Tama and Tosho). Culture of throat swabs every November and the following February during the 20-year period were made and serological grouping and typing for isolates were done by T agglutination method. The results were as follows. 1) Serological group of hemolytic streptococci isolated from children were 3,188 strains (76.3%) for isolates of group A out of total strains of 4,176, 569 strains (13.6%) for isolates group B, 63 strains (1.5%) for isolates of group C and 356 strains (8.5%) for isolates of group G. 2) The most dominant was T12 during 1979-1998, and other relatively frequent serotypes were T28, T1, T4, T6 in that order. These ranks of and the main epidemic serotypes showed a similar trend in the 3 areas. 3) The isolation rates of group A streptococci were 15.9% in Tokubetsuku, 17.1% in Tama and 14.9% in Tosho. The average of 3 areas were 15.8%. 4) The epidemic cases seemed to be caused by group A streptococci were 20 cases, their isolated serotype were 7 cases by T28, 5 cases by T12, 4 cases by T6, 2 cases by T4, each 1 case by T1 and T25. 5) A total of 2,927 strains of group A streptococci were examined for drug sensitivity. All strains were sensitive to beta-lactam group of antibiotics (benzylpenicillin and cephaloridine). Resistant (MIC > or = 25 micrograms/ml) to TC, CP and EM etc. were 740 strains (25.3%) in this study. The incidence of resistant strains were to TC 493 strains (66.6%) out of 740 strains, 81 strains (10.9%) for TC.CP, 72 strains (9.7%) for EM and 66 strains (8.9%) for TC.CP.EM.OL.LCM. TC resistant strains have not varied much through the whole period, but CP and EM resistant strains were very variable by year. Many resistant strains to TC were T4, to EM and multiple drug resistant were T12. 6) The rates of isolates of the same type of group A streptococci in school child individual during for the tests taken twice a year were 12.3%, indicating group A streptococci, according to the duration of the carrier state, seems to be a short period.

No abstract

Among the group A streptococci isolated during the period 1956 to 1978 from the pharynx and the nostril of the scarlet fever patients quarantined in the Tokyo Metropolitan Toshima Hospital within 1 week of hospitalization, 1,586 strains of types 4, 6 and 12, the most prevalent serotypes, were estimated for their sensitivities to various antibiotics. Among the sensitivities, those to tetracycline (TC), chloramphenicol (CP) and erythromycin (EM), these being in close relation to prevalent serotypes, are to be reported. The first appearance of TC-resistant strain was seen in one strain (type 6) isolated in 1959, and, in 1964, the resistant strain increased in proportion in accordance with the prevalence of type 4. The resistant strain decreased a little in 1968 and in 1969, increased again from 1970, exceeded over 90% from 1973, and reached 100% in 1978. The first appearance of CP-resistant strain was seen in one strain (type 4) isolated in 1969, and then the resistant strain increased year by year along with the prevalence of type 12. The first appearance of EM-resistant strain was seen in 30 strains (type 12) isolated in 1972, and then, similarly to the case of CP-resistance, the resistant strain increased year by year together with the prevalence of type 12. Meanwhile, among the 1,586 strains isolated at the time of hospitalization and estimated of their minimum inhibitory concentrations (MIC), 932 strains (58.8%), 452 strains (28.5%), and 574 strains (36.2%) showed resistance to TC, CP, and EM, respectively. Variations of drug-resistance by serotypes were as follows: TC-resistant strains increased in accordance with the prevalence of type 4 in 1964; CP- and EM-resistant strains increased in accordance with the prevalence of type 12 in 1972; and type 6 strains were low in the rate of resistant strain to any of the three drugs. So far, prevalence of a serotype of group A streptococci has been considered to be caused by the accumulation of the subjects non-immune to the serotype. In the present study, a phenomenon was observed that prevalence of a serotype was effected by the state of resistance-acquisition to commonly used drugs. It would be clear that the resistance-acquisition plays, in addition to the immune state, a great role in evoking prevalence of a serotype.

No abstract