title: Characterization of a genomic island in Stenotrophomonas maltophilia that carries a novel floR gene variant.
abstract: OBJECTIVE
  To characterize the chromosomally encoded novel floR gene variant floRv from Stenotrophomonas maltophilia of porcine origin and elucidate the gene order and content of the floRv-flanking regions in an MDR genomic island (GI).
  
  
  METHODS
  Whole genome sequencing was used to identify the unknown florfenicol resistance gene in S. maltophilia strain GZP-Sm1. The candidate gene was cloned into pMD19-T and Escherichia coli transformants carrying this vector were tested for phenicol MICs. Flanking sequences of the florfenicol resistance gene were identified by a de novo assembly and a primer walking strategy.
  
  
  RESULTS
  GZP-Sm1 carried a floR gene variant, designated floRv. E. coli clones carrying this gene were resistant to chloramphenicol and florfenicol. The deduced 404 amino acid FloRv protein showed 84.1%-91.8% amino acid identity to various FloR proteins. The gene floRv was located in an MDR region within a 40 226 bp GI region. Six resistance genes, including floRv (phenicol resistance), tetR-tetA(A) (tetracycline resistance), strA/strB (streptomycin resistance), sul1 (sulphonamide resistance) and aadA2 (streptomycin/spectinomycin resistance), were located in this MDR region. PCR analysis revealed that the GI was not stable and could be excised from the chromosome as a circular intermediate.
  
  
  CONCLUSIONS
  The floRv gene was identified in a porcine S. maltophilia isolate. Six resistance genes including floRv were located in a novel GI. As an opportunistic pathogen in animals and humans, S. maltophilia might act as a resistance gene reservoir in farm environments. Its contribution to the spread of resistance genes to other pathogens should be monitored.
authors.affiliation: National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University, Beijing 100193, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: He
authors.affiliation: National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University, Beijing 100193, P. R. China.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shen
authors.affiliation: Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Höltystr. 10, 31535 Neustadt-Mariensee, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwarz
authors.affiliation: National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University, Beijing 100193, P. R. China.
authors.forename: Congming
authors.initials: C
authors.lastname: Wu
authors.affiliation: National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University, Beijing 100193, P. R. China wangyang@cau.edu.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D015870:Gene Expression; D044404:Genomic Islands; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; C035534:florfenicol; D013839:Thiamphenicol
keywords: MDR; food animals; integration; phenicol exporter genes