Identification of a novel fosfomycin resistance gene (fosA2) in Enterobacter cloacae from the Salmon River, Canada

Lett Appl Microbiol. 2011 Apr;52(4):427-9. doi: 10.1111/j.1472-765X.2011.03016.x. Epub 2011 Feb 21.


Aims: To investigate the occurrence of fosfomycin-resistant (fos(R) ) bacteria in aquatic environments.

Methods and results: A fos(R) strain of Enterobacter cloacae was isolated from a water sample collected at a site (50°41'33·44″N, 119°19'49·50″W) near the mouth of the Salmon River at Salmon Arm, in south-central British Columbia, Canada. The strain was identified by PCR screening for plasmid-borne, fosA-family amplicons, followed by selective plating. Sequencing of the resistance gene cloned using PCR primers to conserved flanking DNA revealed a new allele (95% amino acid identity to fosA), and I-Ceu I PFGE showed that it was chromosomally located. In Escherichia coli, the cloned DNA conferred a greater resistance to fosfomycin than its fosA counterpart.

Conclusions: Gene fosA2 conferred fosfomycin resistance in an environmental isolate of Ent. cloacae.

Significance and impact of the study: The repurposing of older antibiotics should be considered in the light of existing reservoirs of resistance genes in the environment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Base Sequence
  • British Columbia
  • Drug Resistance, Bacterial
  • Enterobacter cloacae / drug effects
  • Enterobacter cloacae / genetics*
  • Enterobacter cloacae / isolation & purification
  • Fosfomycin / pharmacology*
  • Genes, Bacterial*
  • Molecular Sequence Data
  • Rivers / microbiology*


  • Anti-Bacterial Agents
  • Fosfomycin