Analysis of a case of recurrent bacteraemia due to group A Streptococcus equisimilis by pulsed-field gel electrophoresis.

An 86-year-old woman with a history of metastatic breast cancer developed two episodes of streptococcal bacteraemia and erysipelas separated by an interval of 3 months. The isolates belonged to Lancefield group A but were biochemically identified as Streptococcus equisimilis. The similarity of the two isolates was established by DNA macrorestriction analysis and pulsed-field gel electrophoresis, indicating that the second episode was due to relapse and not reinfection.