title: Presence and new genetic environment of pleuromutilin-lincosamide-streptogramin A resistance gene lsa(E) in Erysipelothrix rhusiopathiae of swine origin.
abstract: Erysipelothrix rhusiopathiae is a Gram-positive bacillus that causes erysipelas in swine. In recent years, erysipelas infection among swine in China has been increasing. A combined resistance phenotype to pleuromutilins, lincosamides, and streptogramin A (PLSA phenotype) was found in some E. rhusiopathiae isolates. The aim of this study was to identify the resistance genes responsible for the PLSA phenotype in E. rhusiopathiae strains and to map the genetic environment of the identified resistance gene. A total of 46 E. rhusiopathiae isolates from 31 pig farms in China were studied. Minimum inhibitory concentrations (MICs) of 11 antimicrobial agents were determined by broth microdilution method. Seven were highly resistant to tiamulin (MICs 32 μg/ml) and clindamycin (MICs 64 μg/ml). Resistance genes responsible for the PLSA phenotype were screened by PCR. The lsa(E), spw, lnu(B), aadE and aphA3 genes were detected in strains had the PLSA phenotype, whereas none was detected in susceptible strains. The genetic environment of lsa(E) gene was determined by whole-genome sequencing and overlapping PCR assays. A novel multiresistance gene cluster, orf1-aadE-apt-spw-lsa(E)-lnu(B)-rec-orf2-orf1-aadE-sat4-aphA3, was found. Horizontal gene transfer experiments and whole-genome sequencing suggested that the lsa(E)-carrying multiresistance gene cluster was located in the chromosome. This is the first molecular characterization of PLSA resistance in E. rhusiopathiae. The lsa(E), spw and lnu(B) genes were found in E. rhusiopathiae for the first time. A novel lsa(E)-carrying multiresistance gene cluster was found. The location of lsa(E) in different gene cluster facilitates its persistence and dissemination.
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Anyun
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Changwen
authors.initials: C
authors.lastname: Xu
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China; "985 Project" Science Innovative Platform for Resource and environment Protection of Southwestern, Sichuan University, Chengdu, Sichuan 610064, PR China. Electronic address: whongning@163.com.
authors.forename: Hongning
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Changwei
authors.initials: C
authors.lastname: Lei
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Bihui
authors.initials: B
authors.lastname: Liu
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Zhongbin
authors.initials: Z
authors.lastname: Guan
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Yang
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life science, Sichuan University, Chengdu, Sichuan 610064, PR China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan 610064, PR China.
authors.forename: Linyao
authors.initials: L
authors.lastname: Peng
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D002681:China; D002981:Clindamycin / Q000494:pharmacology; D004224:Diterpenes / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004888:Erysipelothrix / Q000187:drug effects* / Q000235:genetics*; D019450:Genes, MDR / Q000235:genetics*; D055231:Lincosamides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D011083:Polycyclic Compounds; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D025364:Streptogramin A / Q000494:pharmacology; D013552:Swine / Q000382:microbiology*; D000097567:Pleuromutilins
chemical_list: D000900:Anti-Bacterial Agents; D002981:Clindamycin; D004224:Diterpenes; D055231:Lincosamides; D011083:Polycyclic Compounds; D025364:Streptogramin A; D000097567:Pleuromutilins; C014224:tiamulin
keywords: Erysipelothrix rhusiopathiae; Gram-positive bacteria; Multidrug resistance; lsa(E) gene