This work has been supported by project FIS PI080656 of the Ministerio de Ciencia e Innovacion, Spain. I.R. is the recipient of a grant from the Fundacion para el Fomento en Asturias de la Investigacion Cientifica Aplicada y la Tecnologia (FICYT-BP04-086). M.R.R. and M.C.M. are members of a research unit associated with the Consejo Superior de Investigaciones Cientificas, Spain. The authors are grateful to M.A. Gonzalez-Hevia and M. Bances (Laboratorio de Salud Publica, Oviedo, Spain) for the isolates used in this work and to them and A. Echeita (Laboratorio Nacional de Referencia de Salmonella y Shigella, Instituto de Salud Carlos III, Madrid, Spain) for providing information on the trends of Salmonella enterica in Asturias and Spain.