Livestock-associated methicillin-resistant and in wild Norway rats from Ontario swine farms.

Methicillin-resistant (MRSA) and are important human pathogens that are also carried by animals. The role of wild mammals on farms in their maintenance and transmission, however, is poorly understood. To determine if Norway rats are potential carriers of these bacteria on Canadian farms, we tested 21 rats from swine farms in Ontario. The MRSA spa type t034 was isolated from 1 (4.8%) rat. This livestock-associated strain often colonizes pigs and pig farmers, suggesting that transmission among rats and pigs or environmental transmission is possible on pig farms. ribotype 078 was isolated from 1 rat from a different farm. This strain is associated with infection in piglets, calves, and humans. The identification of MRSA and in Norway rats on farms in Canada adds to the growing knowledge about the role of rats in the ecology of these pathogens. Further studies are required to determine if rats play a part in the epidemiology of these pathogens on farms.