During the study, 2351 invasive streptococcal infections were reported in microbiology laboratories in Ontario. Of these, 291 involved patients in hospitals. The researchers also identified 20 hospital outbreaks. Outbreaks were small, involving an average of 2 patients, and lasted an average of 6 days. In most outbreaks, the bacteria were transmitted from patient to patient, most likely on the hands of staff. One fifth of the outbreaks involved patients with necrotizing fasciitis admitted to intensive care units.