Clustering of group A streptococcal infections on a burns unit: important lessons in outbreak management.

In a 12-month period 37 patients and four members of staff on a burns unit were infected or colonized by Streptococcus pyogenes (Group A streptococcus). One patient became septicaemic and died. Serotyping revealed five distinct clusters against a low background level of infection. Infection control measures included isolation, screening of patients, staff and environment and the use of prophylactic antibiotics for uninfected patients. We discuss the role of staff and patient carriers and the environment as a continuing source of infection, and the importance of serotyping in outbreak epidemiology.