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.
© 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.