Distribution and Upper Limit of Normal Antistreptolysin O Concentrations of School / 감염

BACKGROUND: Antistreptolysin O (ASO) is very useful as an indicator of recent streptococcal infections and their sequelae, such as rheumatic fever and acute glomerulonephritis. To interpret single ASO level of patients, the upper limit of normal (ULN) ASO from the same age group in the area should be known. As Streptococcus pyogenes infections are quite common in elementary school, we measured ASO and analyzed them by the results of throat culture to determine upper limit of normal ASO of school children in Chinju area. METHODS: ASO concentrations were measured quantitatively by nephelometry on 436 sera of healthy elementary school children in Chinju area. Throat cultures were taken at the same time to evaluate the relationship between ASO concentrations and throat culture results, including serogroup, colony forming units (CFU), and M types. RESULTS: The mean ASO concentration was 285IU/ml and the upper limit of normal ASO was 433IU/ml. The ASO levels were even (253-285IU/ml) through whole school grades except the 5th grade (350IU/ml). Not only the carriers of group A streptococci, but also those of group C or group G streptococci had higher ASO levels. The children from whom more than 10 CFU of S. pyogenes were isolated showed higher ASO levels than those who had less than 10 CFU. The ASO levels were higher in M type 6 or 22 compared to M type 12 or 28. CONCLUSIONS: The upper limit of normal ASO of children in Chinju was 433IU/ml, that is between Seoul(326IU/ml) and Chungnam (499IU/ml). The children who had more than 10 CFU tended to have higher ASO levels, which indicate asymptomatic infections, are associated with burden of bacteria. Group C or group G streptococci may induce serum response like group A streptococci. Certain M types may be implicated as strong producer of streptolysin O.

Comparison of M-serotypes of Streptococcus pyogenes isolated from healthy elementary school children in two rural areas

Serotypings have been used as markers for epidemiological surveys of Streptococcus pyogenes infections. Seventy-seven strains of S. pyogenes isolated from the throats of elementary school children in Kangwon Province in Korea in March and April 1992 were serotyped with M and/or opacity factor (OF) antisera. Sixty-eight strains of S. pyogenes from healthy school children in Chungnam Province in March 1993 were also serotyped and the distribution of serotype was compared with the isolates from those living in Kangwon Province. The distributions of M types were quite different between the two areas. M-78 (46.8%) and M-28 (22.1%) were most frequently encountered in Kangwon Province, while M-5 (20.6%), M-12 (16.2%), M-3 (13.2%), M-1 (11.8%) and M-62 (11.8%) were frequently isolated in Chungnam Province. Eighty-seven percent of strains in Kangwon produced OF while 33.2% of those in Chungnam produced OF (p< 0.0001). The difference in the distribution of serotypes and of OF production in the isolates from the children in the two provinces may be responsible for differences in the epidemiology of group A streptococcal infections and their sequelae.