RESUMEN
Background: Pathogenic strains of Yersinia enterocolitica harbor a virulence plasmid of 45-48 megadalton that can be detected using different techniques. Rodents are important reservoirs of Y enterocolitica. Aim: To investigate the carrier status of Y enterocolitica in murine rodents. Material and methods: Two hundred sixty one mice and rats were captured in rural and urban areas of Valdivia. Y enterocolitica was cultured from viscera and fecal homogenates. Virulence plasmids were detected using crystal violet binding. Results: Thirteen Y enterocolitica strains were isolated from 11 rodents. Ten strains belonged to the biotype 1 and three to the biotype 4, serotype O:3. The most frequently infected rodent species were R norvergicus (20 per cent), followed by A longipilis (11 per cent), A olivaceus (2 per cent) and O longicaudatus (2 per cent). Conclusions: Rodents, and specially the domestic rat, can be an important source of Y enterocolitica infection for human and susceptible animal species