title: Plasmid-mediated quinolone resistance genes and antibiotic residues in wastewater and soil adjacent to swine feedlots: potential transfer to agricultural lands.
abstract: BACKGROUND
  Inappropriate use of antibiotics in swine feed could cause accelerated emergence of antibiotic resistance genes, and agricultural application of swine waste could spread antibiotic resistance genes to the surrounding environment.
  
  
  OBJECTIVE
  We investigated the distribution of plasmid-mediated quinolone resistance (PMQR) genes from swine feedlots and their surrounding environment.
  
  
  METHODS
  We used a culture-independent method to identify PMQR genes and estimate their levels in wastewater from seven swine feedlot operations and corresponding wastewater-irrigated farm fields. Concentrations of (fluoro)quinolones in wastewater and soil samples were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry.
  
  
  RESULTS
  The predominant PMQR genes in both the wastewater and soil samples were qnrD, qepA, and oqxB, whereas qnrS and oqxA were present only in wastewater samples. Absolute concentrations of all PMQR genes combined ranged from 1.66 × 107 to 4.06 × 108 copies/mL in wastewater and 4.06 × 106 to 9.52 × 107 copies/g in soil. Concentrations of (fluoro)quinolones ranged from 4.57 to 321 ng/mL in wastewater and below detection limit to 23.4 ng/g in soil. Significant correlations were found between the relative abundance of PMQR genes and (fluoro)quinolone concentrations (r = 0.71, p = 0.005) and the relative abundance of PMQR genes in paired wastewater and agricultural soil samples (r = 0.91, p = 0.005).
  
  
  CONCLUSIONS
  Swine feedlot wastewater may be a source of PMQR genes that could facilitate the spread of antibiotic resistance. To our knowledge, this is the first study to examine the occurrence of PMQR genes in animal husbandry environments using a culture-independent method.
authors.affiliation: Key Laboratory of Development and Evaluation of Chemical and Herbal Drugs for Animal Use, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Thanh
authors.initials: T
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Shao
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shen
authors.forename: Shaochen
authors.initials: S
authors.lastname: Wang
authors.forename: Yongning
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000383:Agriculture; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D010957:Plasmids; D015363:Quinolones / Q000494:pharmacology*; D012989:Soil Pollutants / Q000494:pharmacology*; D013552:Swine; D014874:Water Pollutants, Chemical / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical