title: Clonal spread of mcr-1 in PMQR-carrying ST34 Salmonella isolates from animals in China.
abstract: Since initial identification in China, the widespread geographical occurrence of plasmid-mediated colistin resistance gene mcr-1 in Enterobacteriaceae has been of great concern. In this study, a total of 22 Salmonella enterica were resistant to colistin, while only five isolates which belonged to ST34 Salmonella enterica serovar Typhimurium (S. Typhimurium) were mcr-1 positive. Four of them shared nearly identical PFGE type, although they were from different host species and diverse geographical locations. All the mcr-1-positive S. Typhimurium exhibited multi-resistant phenotypes including ampicillin, streptomycin, gentamicin, florfenicol, nalidixic acid, tetracycline, trimethoprim-sulfamethox, in addition to colistin. The oqxAB and aac(6')-Ib-cr genes were present alone or in combination in four (80.0%) and five (100%) isolates, respectively. The mcr-1 gene was located on a transferable IncI2 plasmid in the four genetically related strains. In the other one strain, mcr-1 was located on an approximately 190 kb IncHI2 plasmid. In conclusion, we report five mcr-1-positive S. Typhimurium/ST34 isolates. Both clonal expansion and horizontal transmission of IncI2-type plasmids were involved in the spread of the mcr-1 gene in Salmonella enterica from food-producing animals in China. There is a great need to monitor the potential dissemination of the mcr-1 gene.
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Xing-Ping
authors.initials: XP
authors.lastname: Li
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Liang-Xing
authors.initials: LX
authors.lastname: Fang
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Jia-Qi
authors.initials: JQ
authors.lastname: Song
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xia
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Huo
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Jin-Tao
authors.initials: JT
authors.lastname: Fang
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Liao
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Ya-Hong
authors.initials: YH
authors.lastname: Liu
authors.affiliation: Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Zhejiang, P. R. China.
authors.forename: Youjun
authors.initials: Y
authors.lastname: Feng
authors.affiliation: National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.|Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
mesh_terms: D000818:Animals; D001483:Base Sequence; D002999:Clone Cells; D003091:Colistin; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010957:Plasmids / Q000378:metabolism*; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000302:isolation & purification*
chemical_list: D003091:Colistin