title: Salmonella enterica serotype Typhimurium carrying hybrid virulence-resistance plasmids (pUO-StVR): a new multidrug-resistant group endemic in Spain.
abstract: The epidemiological impact in Spain of an emerging group of multidrug-resistant Salmonella enterica serotype Typhimurium, characterized by the presence of virulence-resistance hybrid plasmids (termed pUO-StVR) that are related to the S. Typhimurium virulence plasmid pSLT, was evaluated. Adscription to the group was based on detection of the bla(OXA-1) gene (encoding ampicillin resistance) by PCR, and identification of a pUO-StVR plasmid through hybridization with specific probes for virulence (spvC) and resistance (bla(OXA-1)) genes. In this way, 57 out of 134 ampicillin-resistant clinical isolates of S. Typhimurium, collected over 2002-2004 in 21 Spanish cities, were assigned to the group, which can be already regarded as endemic. Most isolates (>89%) shared the following features: (i) resistance to ampicillin, chloramphenicol, streptomycin/spectinomycin, sulfonamides, and tetracycline, encoded by bla(OXA-1)-catA1-aadA1-sul1-tet(B); (ii) a class 1 integron (InH) with the bla(OXA-1)-aadA1 gene cassettes within its variable region of ca. 2000bp; (iii) the spvC, rck, samA, oriT, traT, traX, repA (RepFIIA), and parA/B genes (but not rsk and pefABCD) of pSLT; (iv) a hybrid plasmid of ca. 125kb, termed pUO-StVR2, where the resistance and virulence genes are located. However, intra-group diversity was also detected, since a total of four resistance phenotypes, five resistance genotypes, two integron profiles, five plasmid variants (pUO-StVR2, 4-7, differing in size, restriction profile and/or resistance pattern), 15 XbaI-BlnI combined macrorestriction profiles, and five phage types were identified. Each hybrid plasmid was revealed as a distinctive BlnI band, through hybridization with pUO-StVR2. The genetic markers used, together with the knowledge generated in the present study, could be applied to epidemiological surveillance of S. Typhimurium pUO-StVR worldwide.
authors.affiliation: Departamento de Biología Funcional, Area de Microbiología, Facultad de Medicina, University of Oviedo, C/Julián Clavería no 6, E-33006 Oviedo, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Herrero
authors.forename: M Rosario
authors.initials: MR
authors.lastname: Rodicio
authors.forename: M Aurora
authors.initials: MA
authors.lastname: Echeita
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Mendoza
mesh_terms: D000668:Ampicillin Resistance / Q000235:genetics; D001434:Bacteriophage Typing; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D019353:Endemic Diseases / Q000706:statistics & numerical data; D006801:Humans; D032023:Integrons / Q000235:genetics; D010957:Plasmids / Q000235:genetics*; D012480:Salmonella Infections / Q000453:epidemiology; D012486:Salmonella typhimurium / Q000235:genetics* / Q000302:isolation & purification; D013030:Spain / Q000453:epidemiology; D014774:Virulence