title: Detection of the plasmid-encoded fosfomycin resistance gene fosA3 in Escherichia coli of food-animal origin.
abstract: OBJECTIVE
  To investigate the occurrence of plasmid-mediated fosfomycin resistance genes among Escherichia coli from food animals in China.
  
  
  METHODS
  A total of 892 E. coli isolates collected from individual pigs (n=368), chickens (n=196), ducks (n=261), geese (n=35), pigeons (n=20) and partridges (n=12) in Guangdong Province during 2002-08 were screened for the presence of fosA3, fosA and fosC2 by PCR amplification and sequencing. The clonal relationship of fosA3-positive isolates, plasmid content and other associated resistance genes were also characterized.
  
  
  RESULTS
  Twelve (1.3%) E. coli isolates showed resistance to fosfomycin and 10 (1.1%) isolates (4 from pigs, 2 from chickens, 2 from ducks, 1 from a goose and 1 from a pigeon) were positive for fosA3. None of the E. coli isolates was positive for fosA or fosC2. All of the isolates carrying fosA3 were CTX-M producers, and three of them carried rmtB. Most of the fosA3-harbouring isolates were found to be clonally unrelated. The fosA3 genes were flanked by IS26. Two fosA3 genes co-localized with rmtB and blaCTX-M-65 on indistinguishable F33:A-:B- plasmids that carried three addiction systems (pemI/pemK, hok/mok/sok and srnB). Four, one and one fosA3 genes were found to be associated with IncN (ST8 type), IncI1 and F2:A-:B- plasmids, respectively.
  
  
  CONCLUSIONS
  We discovered that fosA3 is always associated with blaCTX-M, which facilitates its quick dispersal. The emergence of fosA3 in food animals could impact on human medicine by the potential transfer of resistance through the food chain.
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University (SCAU), Guangzhou, People's Republic of China.
authors.forename: Jianxia
authors.initials: J
authors.lastname: Hou
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Yang
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Zeng
authors.forename: Luchao
authors.initials: L
authors.lastname: Lv
authors.forename: Tong
authors.initials: T
authors.lastname: Yang
authors.forename: Dachuan
authors.initials: D
authors.lastname: Lin
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology*; D002681:China; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D005578:Fosfomycin / Q000494:pharmacology*; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D005578:Fosfomycin