Community outbreak of invasive group A streptococcal infection.

In a two-month period, three cases of septicaemia and one of suppurative tenosynovitis caused by a single strain of Lancefield group A streptococcus, serotype T/M/R 3/3/3, occurred in the district of Nairn (population: 10,239). A primary portal of entry for the organism could not be identified in any of the cases. Laboratory isolates from all four patients were highly susceptible to beta-lactam antibiotics, but prompt treatment failed to prevent the deaths of two previously healthy adults. Group A streptococci of M-type 3 have not previously been associated with outbreaks of invasive infection.