Typing of group A streptococci by pulsed field gel electrophoresis

Restriction endonuclease (Sma I) digestion patterns of chromosomal DNAs of T types 1 and 3 (T1 and T3) group A streptococci (GAS), isolated at two hospitals in Toyama Prefecture from 1983 to 1994, were analysed by pulsed-filed gel electrophoresis (PFGE). One hundred twenty seven isolated of T1 GAS were further divided into 5 PFGE types, which were provisionally designated as T1-1 approximately T1-5. Two epidemics of T1 GAS were observed during the 1983 approximately 1994 period, the first of which (1887 approximately 1988) seemed to be caused by T1-2, and the second (1991 approximately 1993) by T1-5. Some differences in biological characteristics between the two PFGE type strains were also observed. On the other hand, eighty one T3 GAS strains were divided into only two PFGE types, provisionally designated as T3-1 and T3-2, most of which belonged to T3-2. Naturally, both epidemics by T3 GAS, first from 1985 to 1986 and second from 1993 to 1994, seemed to be caused by the same PFGE type, T3-2. No differences in biological characteristics were observed between T3-1 and T3-2 strains.