- A Muotiala: National Public Health Institute, Department of Bacteriology, Helsinki, Finland.
Within 9 days in a day-care centre of 20 children 3 cases and 2 suspected cases of perianal infection (PAI) were revealed. The causative agent for PAI was confirmed to be beta-haemolytic group A streptococcus (GAS). The isolates were further characterized by T- and M-serotyping, conventional restriction endonuclease analysis (REA) and pulsed field gel electrophoresis (PFGE). The typing methods revealed that all outbreak isolates were of same T28R28-serotype and genetically identical. Unrelated, control GAS isolates of the same serotype differed genetically from the outbreak isolates indicating that a single clone had caused the perianal infections.