title: Characterization of Salmonella enterica Serovar Typhimurium Isolates from Pigs and Pig Environment-Related Sources and Evidence of New Circulating Monophasic Strains in Spain.
abstract: A total of 117 Salmonella enterica serovar Typhimurium and 59 monophasic Salmonella Typhimurium (S. enterica serovar 4,[5],12:i:-) strains isolated between 2008 and 2012 from pig, wild bird, rodent, and farm environment samples from the northeast of Spain were characterized by phage typing, antibiotic susceptibility testing, and multiple-locus variable-number tandem repeat analysis in order to evaluate their phenotypic and genetic relatedness. In Salmonella 4,[5],12:i:-, the most prevalent phage types were U311 (40.7%) and DT195 (22%), which did not correspond with the so-called Spanish clone and generally showed a different resistance pattern (ASSuT). Antibiotic resistance was found in 85.8% of the isolates, with 94.1% of them displaying multidrug resistance. Multiple-locus variable-number tandem repeat analysis identified 92 different profiles, six of them shared by both serovars. The minimum spanning tree showed one major cluster that included 95% of the Salmonella 4,[5],12:i:- isolates, which came from different animal sources, geographic locations, and time periods, suggesting high clonality among those Salmonella strains and the ability to spread among pig farms. Overall, isolates of Salmonella 4,[5],12:i:- were more similar to European strains than to the well-characterized Spanish clone. The spread of these new strains of Salmonella 4,[5],12:i:- would likely have been favored by the important pig trade between this Spanish region and other European countries. The overall high prevalence of multidrug resistance observed in these new strains should be noted.
authors.affiliation: Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Instituto Agroalimentario de Aragón - IA2 - (CITA-Universidad de Zaragoza), Avenida Montañana 930, 50059, Zaragoza, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Andrés-Barranco
authors.affiliation: CONICET-UCC Unidad Asociada: Área Ingeniería, Ciencias Agrarias, Biológicas y de la Salud, Avenida Armada Argentina 3555, 5017 Córdoba, Argentina.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Vico
authors.affiliation: Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Instituto Agroalimentario de Aragón - IA2 - (CITA-Universidad de Zaragoza), Avenida Montañana 930, 50059, Zaragoza, Spain.
authors.forename: Clara María
authors.initials: CM
authors.lastname: Marín
authors.affiliation: Seccón de Enterobacterias, Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Herrera-León
authors.affiliation: Departamento de Patología Animal, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), Avenida Miguel Servet 177, 50013, Zaragoza, Spain. rcmainar@unizar.es.
authors.forename: Raú Carlos
authors.initials: RC
authors.lastname: Mainar-Jaime
mesh_terms: D000818:Animals; D001434:Bacteriophage Typing; D004352:Drug Resistance, Microbial; D004783:Environmental Microbiology; D056426:Genetic Loci; D014644:Genetic Variation; D018598:Minisatellite Repeats; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D065288:Serogroup; D013030:Spain; D013552:Swine / Q000382:microbiology*