Molecular epidemiology of Salmonella Enteritidis in humans and animals in Spain
Antimicrobial Agents and Chemotherapy publica este artículo de investigación
2 de abril de 2025
Salmonella Enteritidis, the most prevalent serovar causing human gastroenteritis, has been traditionally linked to poultry sources. Although antimicrobial resistance (AMR) is not common in this serovar, increasing levels of resistance to fluoroquinolones and ampicillin have been reported in 42 the last years. Here, 298 isolates retrieved from different sources (human, livestock, wildlife, food and
environment) and years (2002-2021) in Spain were analysed to evaluate their diversity, the distribution of AMR-conferring genes (ARGs) and mutations, and reconstruct the epidemiology of infection due to this serovar. Isolates were clustered in two major clades (I, II), with strains in clade I (including 61.5% of all human isolates) displaying a pan-susceptible phenotype and not carrying AMR determinants. In contrast, clade II included 80.7% of isolates from animal/food/environmental sources, with the majority (69.8%) harboring mutations in the quinolone resistance determinant regions (QRDR). ARGs, though rare, were mostly found in clade II strains that also carried plasmid
replicons, among which IncX1 was the most common. Although higher levels of phenotypic resistance were found in animal isolates, extended-spectrum beta-lactamase, plasmid mediated AmpC and carbapenemase-encoding genes were only found among human isolates. In summary, the majority of human and animal isolates from Spanish sources in our collection were classified in different
phylogenetic branches, suggesting additional sources are contributing to the occurrence of foodborne infections in Spain. Furthermore, the different distribution of virulence factors and ARGs in isolates from different sources and its association with specific plasmids suggest the presence of different dynamics contributing to the selection of resistant strains
Samper-Cativiela C., Torre-Fuentes L., Bernabé Diéguez B., Maex M., Ugarte-Ruiz M., Carrizo-Coronado P., Hernandez M., Hofle U., Saez-Llorente JL., De Frutos C., Aguero M., Moreno MA., Dominguez L., Herrera-Leon S. y Alvarez J..
 | Servicio de Zoonosis de Transmisión Alimentaria y Resistencia a Antimicrobianos (ZTA). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM). |
| Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM). |
 | Empresa de Tecnologías y Servicios Agrarios, S.A. (TRAGSATEC). Grupo Tragsa. |
| Division of Human Bacterial Diseases. Sciensano. | |
 | Departamento de 25 Anatomía Patológica, Microbiología, Medicina Preventiva y Salud Pública, Medicina Legal y Forense. Facultad de Medicina. Universidad de Valladolid (UVa). |
| Instituto de Investigación en Recursos Cinegéticos (IREC). Consejo Superior de Investigaciones Científicas (CSIC). Universidad de Castilla La Mancha (UCLM). Gobierno de Castilla-La Mancha (JCCM). | |
| Subdirección General de Sanidad e Higiene Animal y Trazabilidad. Dirección General de la Producción Agraria. Ministerio de Agricultura, Pesca y Alimentación (MAPA). | |
| Laboratorio Central de Veterinaria (LCV). Ministerio de Agricultura, Pesca y Alimentación (MAPA). | |
 | Laboratorio de Referencia e Investigación en Resistencia a Antibióticos e Infecciones Relacionadas con la Asistencia Sanitaria. Centro Nacional de Microbiología (CNM). Instituto de Salud Carlos III (ISCIII). |
