We examined three populations from the Tehran region and the North part of Iran (Gilan), in
all more than 5000 individuals, for carriage of Streptococcus pyogenes (group A streptococci;
GAS). Children or adults with acute pharyngotonsillitis and healthy school children harboured
GAS in 34·1, 20·0 and 21·0%, respectively. Typing of 421 randomly selected isolates showed a
predominance of M-types M4, M5, M11, M12, as well as the provisional type 4245; however,
many of the isolates were T and M non-typable. Forty-three percent of all strains were opacity
factor (OF) negative. The type distribution differed markedly from that reported in 1973–4,
when M types 1 and 12 were predominant.