title: Nucleotide sequence of the chromosomal region conferring multidrug resistance (R-type ASSuT) in Salmonella Typhimurium and monophasic Salmonella Typhimurium strains.
abstract: OBJECTIVE
  The aim of this study was to sequence the chromosomal region conferring resistance to ampicillin, streptomycin, sulphonamides and tetracycline (R-type ASSuT) in a Salmonella Typhimurium (STM) monophasic strain (4,[5],12:i:-) belonging to the PFGE profile STYMXB.0079. The presence of this resistance region and the analysis of its genetic environment was investigated in a selection of strains.
  
  
  METHODS
  A Sau3A1 genomic library was used to determine the nucleotide sequence of the genomic resistance region. PCRs were performed on 10 epidemiologically unrelated Salmonella strains, both STM and monophasic STM, with R-type ASSuT and PFGE profile STYMXB.0079, in order to investigate the presence of the resistance genes, the left and right junctions and the internal regions of the resistance region, as well as the genetic environment.
  
  
  RESULTS
  The genomic resistance region consisted of two regions, resistance region 1 (RR1), conferring resistance to ampicillin, streptomycin and sulphonamides, and resistance region 2 (RR2), conferring tetracycline resistance. These resistance regions were both surrounded by IS26 elements and sequence comparative analysis showed 99% sequence identity with a region of plasmid pO111_1 from an Escherichia coli strain. All 10 strains were positive for the four resistance genes, the left and right junctions and the internal regions of RR1 and RR2. Concerning the genetic environment, all the strains lacked the STM1053-1997 and STM2694 genes, while only monophasic STM strains showed deletion of the fljA-fljB operon.
  
  
  CONCLUSIONS
  This study describes two resistance regions localized on the bacterial chromosome of a clonal lineage of STM and monophasic STM that are widespread in Italy.
authors: Department of Infectious, Parasitic and Immuno-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy. claudia.lucarelli@iss.it
authors: Claudia
authors: C
authors: Lucarelli
authors: Anna Maria
authors: AM
authors: Dionisi
authors: Emma
authors: E
authors: Filetici
authors: Slawomir
authors: S
authors: Owczarek
authors: Ida
authors: I
authors: Luzzi
authors: Laura
authors: L
authors: Villa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000235:genetics; D005838:Genotype; D006801:Humans; D007558:Italy; D008969:Molecular Sequence Data; D058889:Molecular Typing; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012480:Salmonella Infections / Q000382:microbiology; D012486:Salmonella typhimurium / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial