Genetic relatedness of group A streptococci of the newly designated serotype M90 causing a food-borne outbreak and sporadic infections.

Twenty-six isolates of the newly designated M90 serotype group A Streptococcus (GAS) from a large food-borne outbreak of pharyngitis in Greece and six M90 sporadic isolates from UK, were typed by pulsed-field gel electrophoresis (PFGE). Twenty-four outbreak isolates were identical and two closely related. The Greek isolates were possibly related with one UK isolate, while other sporadic isolates exhibited distinct PFGE profiles from the former isolates.