title: Evidence for a second genomic island conferring multidrug resistance in a clonal group of strains of Salmonella enterica serovar Typhimurium and its monophasic variant circulating in Italy, Denmark, and the United Kingdom.
abstract: During the 2000s, a new clonal group with resistances to ampicillin, streptomycin, sulfonamides, and tetracycline (ASSuT) emerged in Italy among strains of Salmonella enterica serovar Typhimurium and its monophasic variant, Salmonella enterica subspecies enterica serovar 4,[5],12:i:-. The PulseNet Europe database allowed us to identify ASSuT strains of both S. Typhimurium and its monophasic variant, isolated in Denmark and the United Kingdom, with the same or very closely related pulsed-field gel electrophoresis (PFGE) patterns as the Italian strains, suggesting that the ASSuT clonal group is circulating in different European countries. With the aim of analyzing the molecular basis of antibiotic resistance, resistance genes were identified and their localization was investigated in 66 ASSuT strains and, as controls, in 11 strains with different resistance patterns and PFGE profiles, belonging both to S. Typhimurium and to its monophasic variant, isolated from humans in Italy, Denmark, and the United Kingdom. All the ASSuT strains were positive for the following resistance genes: bla(TEM-1), strA-strB, sul2, and tet(B). A localization experiment demonstrated that the ASSuT resistance genes are chromosomally located. This study confirms that a multidrug-resistant clonal group, ASSuT, of S. Typhimurium and its monophasic variant has emerged and is circulating in Italy, Denmark, and the United Kingdom. Moreover, the results of this work demonstrate that the multidrug resistance in this clonal group of Salmonella strains is conferred by a new genomic island.
authors.affiliation: Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy. claudia.lucarelli@iss.it
authors.forename: Claudia
authors.initials: C
authors.lastname: Lucarelli
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Dionisi
authors.forename: Mia
authors.initials: M
authors.lastname: Torpdahl
authors.forename: Laura
authors.initials: L
authors.lastname: Villa
authors.forename: Caterina
authors.initials: C
authors.lastname: Graziani
authors.forename: Katie
authors.initials: K
authors.lastname: Hopkins
authors.forename: John
authors.initials: J
authors.lastname: Threlfall
authors.forename: Alfredo
authors.initials: A
authors.lastname: Caprioli
authors.forename: Ida
authors.initials: I
authors.lastname: Luzzi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D003718:Denmark; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D044404:Genomic Islands; D005838:Genotype; D006801:Humans; D007558:Italy; D017720:Molecular Epidemiology; D012480:Salmonella Infections / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D006113:United Kingdom
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial
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