Background: In 1998, an unexpected increase of group A streptococci (GAS) in blood cultures was observed at our institution.
Materials and methods: To determine whether they were from unrelated sporadic cases or attributable to a common source, all isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and by automated ribotyping.
Results: Two clusters were found. All isolates, except one, of cluster 2 had been isolated from intravenous drug abusers.
Conclusion: All patients were hospitalized either in different hospitals or at different times in the same hospitals indicating that the putative common source is to be found in the drug community rather than in a particular hospital.