Isolation rates of Streptococcus pyogenes in patients with acute pharyngotonsillitis and among healthy school children in Iran

We examined three populations from the Tehran region and the North part of Iran (Gilan), in all more than 5000 individuals, for carriage of Streptococ cus pyogenes (group A streptococci; GAS). Children or adults with acute pha ryngotonsillitis and healthy school children harboured GAS in 34.1, 20.0 an d 21.0%, respectively. Typing of 421 randomly selected isolates showed a pr edominance of M-types M4, M5, M11, M12, as well as the provisional type 424 5; however, many of the isolates were T and M non-typable. Forty-three perc ent 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.