title: Effect of banning vancomycin analogue avoparcin on vancomycin-resistant enterococci in chicken farms in Taiwan.
abstract: Avoparcin, a vancomycin analogue, was banned as a feed additive in Taiwan in 2000. A nationwide surveillance was conducted to study the prevalence of vancomycin-resistant enterococci (VRE) on chicken farms between 2000 and 2003. Among the 1021 E. faecalis and 967 E. faecium isolates studied, resistance to tetracycline, erythromycin, high-level aminoglycosides, ciprofloxacin and chloramphenicol either increased or remained high except vancomycin. The proportion of VRE decreased, between 2000 and 2003, from 13.7% (22/161) to 3.7% (11/299) for E. faecalis, and 3.4% (4/119) to 0% (0/300) for E. faecium. Only 8.8% (7/80) of the chicken farms surveyed harboured VRE in 2003 compared with 25% (15/60) in 2000. All VRE were resistant to tetracycline and erythromycin. All VRE possess the vanA gene but nearly all (79 of 83 isolates) were susceptible to teicoplanin, indicating VanB phenotype. Some clones were detected from different farms in various regions over the years. We conclude that the frequency of VRE in chicken farms decreased in association with a ban on avoparcin; and the continued presence of VRE may be due to the ability of some strains to persist in the farms, transfer of vancomycin resistance determinants or co-selection by the continued use of other antibiotics.
authors.affiliation: Division of Clinical Research, National Health Research Institutes, Zhunan, Taiwan. lauderdale@nhri.org.tw
authors.forename: Tsai-Ling
authors.initials: TL
authors.lastname: Lauderdale
authors.forename: Yih-Ru
authors.initials: YR
authors.lastname: Shiau
authors.forename: Hui-Ying
authors.initials: HY
authors.lastname: Wang
authors.forename: Jui-Fen
authors.initials: JF
authors.lastname: Lai
authors.forename: I-Wen
authors.initials: IW
authors.lastname: Huang
authors.forename: Pei-Chen
authors.initials: PC
authors.lastname: Chen
authors.forename: Hong-Yi
authors.initials: HY
authors.lastname: Chen
authors.forename: Shiow-Suey
authors.initials: SS
authors.lastname: Lai
authors.forename: Ya-Fang
authors.initials: YF
authors.lastname: Liu
authors.forename: Monto
authors.initials: M
authors.lastname: Ho
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D019729:Carbon-Oxygen Ligases / Q000235:genetics; D002645:Chickens / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D006020:Glycopeptides; D008826:Microbial Sensitivity Tests; D013624:Taiwan; D020713:Vancomycin Resistance / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D006020:Glycopeptides; C071437:VanA ligase, Bacteria; D019729:Carbon-Oxygen Ligases; C016249:avoparcin