title: Residues of chlortetracycline, doxycycline and sulfadiazine-trimethoprim in intestinal content and feces of pigs due to cross-contamination of feed.
abstract: BACKGROUND
  Cross-contamination of feed with low concentrations of antimicrobials can occur at production, transport and/or farm level. Concerns are rising about possible effects of this contaminated feed on resistance selection in the intestinal microbiota. Therefore, an experiment with pigs was set up, in which intestinal and fecal concentrations of chlortetracycline (CTC), doxycycline (DOX) and sulfadiazine-trimethoprim (SDZ-TRIM) were determined after administration of feed containing a 3 % carry-over level of these antimicrobials.
  
  
  RESULTS
  The poor oral bioavailability of tetracyclines resulted in rather high concentrations in cecal and colonic content and feces at steady-state conditions. A mean concentration of 10 mg/kg CTC and 4 mg/kg DOX in the feces was reached, which is higher than concentrations that were shown to cause resistance selection. On the other hand, lower mean levels of SDZ (0.7 mg/kg) and TRIM (< limit of detection of 0.016 mg/kg) were found in the feces, corresponding with the high oral bioavailability of SDZ and TRIM in pigs.
  
  
  CONCLUSIONS
  The relation between the oral bioavailability and intestinal concentrations of the tested antimicrobials, may be of help in assessing the risks of cross-contaminated feed. However, future research is needed to confirm our results and to evaluate the effects of these detected concentrations on resistance selection in the intestinal microbiota of pigs.
authors.affiliation: Operational Directorate Bacterial Diseases, CODA-CERVA (Veterinary and Agrochemical Research Centre), 1180, Brussels, Belgium.|Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
authors.forename: Laura E J
authors.initials: LE
authors.lastname: Peeters
authors.affiliation: Technology and Food Science Unit, Institute for Agricultural and Fisheries Research, 9090, Melle, Belgium.
authors.forename: Els
authors.initials: E
authors.lastname: Daeseleire
authors.affiliation: Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
authors.forename: Mathias
authors.initials: M
authors.lastname: Devreese
authors.affiliation: Technology and Food Science Unit, Institute for Agricultural and Fisheries Research, 9090, Melle, Belgium.
authors.forename: Geertrui
authors.initials: G
authors.lastname: Rasschaert
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Smet
authors.affiliation: Veterinary Epidemiology Unit, Department of Reproduction, Obstetrics and Herd health, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Dewulf
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.|Technology and Food Science Unit, Institute for Agricultural and Fisheries Research, 9090, Melle, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Heyndrickx
authors.affiliation: Operational Directorate Bacterial Diseases, CODA-CERVA (Veterinary and Agrochemical Research Centre), 1180, Brussels, Belgium.
authors.forename: Hein
authors.initials: H
authors.lastname: Imberechts
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.|Department of Biosciences, School of Veterinary Medicine, Ross University, Basseterre, Saint Kitts and Nevis.
authors.forename: Patrick
authors.initials: P
authors.lastname: Butaye
authors.affiliation: Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium. Siska.Croubels@ugent.be.
authors.forename: Siska
authors.initials: S
authors.lastname: Croubels
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002751:Chlortetracycline / Q000737:chemistry; D004318:Doxycycline / Q000737:chemistry; D004338:Drug Combinations; D004350:Drug Residues / Q000737:chemistry*; D005243:Feces / Q000737:chemistry*; D005506:Food Contamination; D005766:Gastrointestinal Contents / Q000737:chemistry*; D013411:Sulfadiazine / Q000737:chemistry; D013552:Swine; D014295:Trimethoprim / Q000737:chemistry; D000096926:Benzenesulfonamides
chemical_list: D000900:Anti-Bacterial Agents; D002751:Chlortetracycline; D004318:Doxycycline; D004338:Drug Combinations; D013411:Sulfadiazine; D014295:Trimethoprim; C024873:sulfadiazine, trimethoprim drug combination; D000096926:Benzenesulfonamides
keywords: Chlortetracycline; Cross-contamination; Doxycycline; Feces; Intestinal content; Oral bioavailability; Pigs; Sulfadiazine; Trimethoprim