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.

Serotypes of Streptococcus pyogenes isolated from healthy school children in Kangwon-do

Seventy-seven Streptococcus pyogenes strains isolated of children of three elementary schools located in Kangwon-do in spring, 1992 were serotyped with M, opacity factor (OF) and T typing antisera. In the M/OF typing results, M-78 (46.8%) and M-28 (22.1%) were most frequently encountered, while M-4 (6.5%), M-12 (5.2%), M-3 (1.3%), M-5 (1.3%) and M-6 (1.3%) were rarely observed. Twelve strains (15.6%) were not typable with M or OF typing system. In the T typing results, T-11 (35.1%) and T-28 (27.3%) were most common. We were able to identify 77.9% of S. pyogenes strains by T typing, 94.8% with T typing and OF typing. With the addition of M typing, 97.4% were typable. Through the serotypings, we could know the basic distribution of serotypes of S. pyogenes of healthy children which could be comparable to those of rheumatic fever, poststreptococcal glomerulonephritis and other severe streptococcal disease.