title: Multilevel selection of bcrABDR-mediated bacitracin resistance in Enterococcus faecalis from chicken farms.
abstract: In this study we isolated 109 Enterococcus faecalis from chicken faecal samples in 6 provinces of China to investigate the prevalence and transmission mechanism of the bacitracin resistance locus bcrABDR in E. faecalis. Thirty-seven bcrABDR-positive E. faecalis were detected with 26 different PFGE clusters. The MLST of 14 positive strains belonged to ST16 and we also detected three new sequence types. S1-PFGE analysis indicated that the locus was located on plasmids presenting different sizes, with the most prevalent size being ~50 kb (13/37). Sequence analysis revealed that 17 out of the 37 strains harbored a 5400-bp central region, in which locus bcrABDR was bracketed by two ISEnfa1 of the same orientation. Two types of bcrABDR alleles, differing in around 10% of their sequence were found. In silico analysis showed that bcrABDR is present in a variety of bacteria including the chicken commensal Enterococcus cecorum. Our results indicate that the use of bacitracin at farms might trigger the emergence and spread of the bacitracin resistance determinant bcrABDR among human bacterial pathogens. The finding of bcrABDR in the chicken commensal E. cecorum indicates that farm animals microbiota can be an important reservoir of resistance genes with relevance for human health.
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Mu-Ya
authors.initials: MY
authors.lastname: Chen
authors.affiliation: Centro Nacional de Biotecnología, CSIC, Darwin 3, Madrid-28049, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Lira
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Hua-Qing
authors.initials: HQ
authors.lastname: Liang
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Rui-Ting
authors.initials: RT
authors.lastname: Wu
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Duan
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Liao
authors.affiliation: Centro Nacional de Biotecnología, CSIC, Darwin 3, Madrid-28049, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Martínez
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Ya-Hong
authors.initials: YH
authors.lastname: Liu
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001414:Bacitracin / Q000627:therapeutic use*; D001715:Bird Diseases / Q000188:drug therapy / Q000382:microbiology*; D002645:Chickens / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D013293:Enterococcus faecalis / Q000502:physiology*; D000072480:Farms; D005243:Feces / Q000382:microbiology; D056426:Genetic Loci / Q000235:genetics; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D064307:Microbiota / Q000235:genetics; D013559:Symbiosis
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D001414:Bacitracin