Methicillin-resistant Staphylococcus aureus epidemic restricted to one health district in Finland: A population-based descriptive study in Pirkanmaa, Finland, years 2001-2011

Background: The incidence of methicillin-resistant Staphylococcus aureus (MRSA) has been low in the Scandinavian countries, including Finland. Methods: We report a population-based, prospective survey of an exceptionally large ongoing MRSA epidemic in a Finnish health district (HD), Pirkanmaa HD, during 2001-2011 caused by 1 strain, spa t067 (FIN-16). Results: The first FIN-16 case in the HD was identified in 2000. Ten years later, 2447 carriers had been found in 95 different institutions. MRSA in carriers was mostly health care-associated (98%). The epidemic emerged in long-term care facilities and gradually spread to acute hospitals. The majority of carriers were elderly people (median age 78 y). Fifty-two percent of new carriers had an infection with MRSA at the time of detection. Conclusions: The incidence of MRSA in Pirkanmaa HD is substantially higher than the incidence for all of Finland. Temporary projects to control MRSA have not proved sufficient to contain this large epidemic.