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Molecular analysis of a gentamicin resistance transposonlike element on plasmids isolated from North American

M E Byrne1, M T Gillespie, R A Skurray

  • 1Department of Microbiology, Monash University, Clayton, Victoria, Australia.

Antimicrobial Agents and Chemotherapy
|November 1, 1990
PubMed

Insights

Plasmid-mediated aminoglycoside resistance in Staphylococcus aureus is linked to a specific determinant. This determinant is associated with transposons Tn4001 and IS257, found on both Australian and North American strains.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Plasmid-encoded resistance to aminoglycosides like gentamicin, tobramycin, and kanamycin (GmTmKmr) is a significant concern in Staphylococcus aureus.
  • Understanding the genetic elements responsible for this resistance is crucial for combating antibiotic resistance.

Purpose of the Study:

  • To investigate the genetic basis of plasmid-mediated aminoglycoside resistance in Staphylococcus aureus isolates from Australia and North America.
  • To characterize the transposon structures associated with the GmTmKmr resistance determinant.

Main Methods:

  • Plasmid DNA analysis
  • Identification and characterization of insertion sequences (IS256 and IS257)
  • Transposon structure determination

Main Results:

  • The GmTmKmr resistance determinant in Australian S. aureus is mediated by the composite transposon Tn4001, flanked by IS256.
  • North American S. aureus plasmids harbor a truncated Tn4001 element associated with IS257, forming a hybrid structure.
  • IS257 elements were also found flanking other resistance determinants and the conjugative transfer region on North American plasmids.

Conclusions:

  • The GmTmKmr resistance determinant in S. aureus is consistently associated with Tn4001 or its derivatives.
  • IS257 plays a role in the organization and spread of multiple resistance genes and mobile elements on S. aureus plasmids.

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