Transposons related to Tn1696 in IncHI2 plasmids in multiply antibiotic resistant Salmonella enterica serovar typhimurium from Australian animals

Amy K. Cain, Xiulan Liu, Steven P. Djordjevic, Ruth M. Hall*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

Conjugative IncHI2 plasmids carrying tetracycline, trimethoprim, and sulphonamide resistance genes were recovered from two multiply antibiotic resistant Salmonella enterica serovar Typhimurium isolates from Australian food-producing animals. Transposons related to the mercury resistance transposon Tn1696 were identified in both IncHI2 plasmids. These transposons contained an In4-type class 1 integron that carried a dfrA5 trimethoprim resistance gene cassette and the sul1 sulfonamide resistance gene. These integrons were located in the same position as In4 in Tn1696. The integron from one isolate includes a large transposon-like structure containing four IS26 and the strAB, sul2, bla(TEM), and aphA1 genes conferring resistance to streptomycin, sulphonamides, ampicillin, kanamycin, and neomycin, respectively. This structure is flanked by an 8-bp duplication, but it includes both the aphA1-containing transposon Tn4352 and a transposon, Tn6029, carrying genes derived from RSF1010 and from Tn2. However, Tn4352 and Tn6029 overlap, sharing one IS26 copy. This suggests that they do not move by a standard transpositional mechanism. A circular intermediate, carrying only the region containing the resistance gene(s) and one of the IS26 bounding it, is proposed as an intermediate.

Original languageEnglish
Pages (from-to)197-202
Number of pages6
JournalMicrobial Drug Resistance
Volume16
Issue number3
DOIs
Publication statusPublished - Sep 2010
Externally publishedYes

Keywords

  • PSEUDOMONAS-AERUGINOSA
  • CLASS-1 INTEGRONS
  • TN21
  • GENTAMICIN
  • EVOLUTION
  • REGION
  • GENE
  • CONSTRUCTION
  • SEQUENCE
  • STRAINS

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