Dissemination of the strA-strB streptomycin-resistance genes among commensal and pathogenic bacteria from humans, animals, and plants

Mol Ecol. 1996 Feb;5(1):133-43. doi: 10.1111/j.1365-294x.1996.tb00299.x.


Gene transfer within bacterial communities has been recognized as a major contributor in the recent evolution of antibiotic resistance on a global scale. The linked strA-strB genes, which encode streptomycin-inactivating enzymes, are distributed worldwide and confer streptomycin resistance in at least 17 genera of gram-negative bacteria. Nucleotide sequence analyses suggest that strA-strB have been recently disseminated. In bacterial isolates from humans and animals, strA-strB are often linked with the suIII sulfonamide-resistance gene and are encoded on broad-host-range nonconjugative plasmids. In bacterial isolates from plants, strA-strB are encoded on the Tn3-type transposon Tn5393 which is generally borne on conjugative plasmids. The wide distribution of the strA-strB genes in the environment suggests that gene transfer events between human, animal, and plant-associated bacteria have occurred. Although the usage of streptomycin in clinical medicine and animal husbandry has diminished, the persistence of strA-strB in bacterial populations implies that factors other than direct antibiotic selection are involved in maintenance of these genes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Bacteria / drug effects
  • Bacteria / genetics
  • Bacteria / isolation & purification
  • Base Sequence
  • Biological Evolution
  • Chromosome Mapping
  • DNA Transposable Elements
  • DNA, Bacterial / genetics
  • Drug Resistance, Microbial / genetics*
  • Gene Transfer Techniques
  • Genes, Bacterial*
  • Humans
  • Molecular Sequence Data
  • Plants / microbiology
  • Replicon
  • Streptomycin / pharmacology*


  • Anti-Bacterial Agents
  • DNA Transposable Elements
  • DNA, Bacterial
  • Streptomycin