title: Detection of the florfenicol resistance gene floR in Chryseobacterium isolates from rainbow trout. Exception to the general rule?
abstract: Bacteria from the family Flavobacteriaceae often show low susceptibility to antibiotics. With the exception of two Chryseobacterium spp. isolates that were positive for the florfenicol resistance gene floR, no clinical resistance genes were identified by microarray in 36 Flavobacteriaceae isolates from salmonid fish that could grow in ≥ 4 mg/L florfenicol. Whole genome sequence analysis of the floR positive isolates revealed the presence of a region that contained the antimicrobial resistance genes floR, a tet(X) tetracycline resistance gene, a streptothricin resistance gene and a chloramphenicol acetyltransferase gene. In silico analysis of 377 published genomes for Flavobacteriaceae isolates from a range of sources confirmed that well-characterised resistance gene cassettes were not widely distributed in bacteria from this group. Efflux pump-mediated decreased susceptibility to a range of antimicrobials was confirmed in both floR positive isolates using an efflux pump inhibitor (phenylalanine-arginine β-naphthylamide) assay. The floR isolates possessed putative virulence factors, including production of siderophores and haemolysins, and were mildly pathogenic in rainbow trout. Results support the suggestion that, despite the detection of floR, susceptibility to antimicrobials in Flavobacteriaceae is mostly mediated via intrinsic mechanisms rather than the horizontally acquired resistance genes more normally associated with Gram-negative bacterial pathogens such as Enterobacteriaceae.
authors.affiliation: Cefas Weymouth laboratory, The Nothe, Barrack Road, Weymouth DT4 8UB, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Verner-Jeffreys
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brazier
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Ramon Y
authors.initials: RY
authors.lastname: Perez
authors.affiliation: Cefas Weymouth laboratory, The Nothe, Barrack Road, Weymouth DT4 8UB, UK.
authors.forename: David
authors.initials: D
authors.lastname: Ryder
authors.affiliation: APHA Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
authors.forename: Roderick M
authors.initials: RM
authors.lastname: Card
authors.affiliation: USDA/ARS National Center for Cool and Cold Water Aquaculture, 11861 Leetown Rd., Kearneysville WV 25430, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Welch
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Rowena
authors.initials: R
authors.lastname: Hoare
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Thao
authors.initials: T
authors.lastname: Ngo
authors.affiliation: APHA Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
authors.forename: Nikki
authors.initials: N
authors.lastname: McLaren
authors.affiliation: APHA Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Ellis
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Bartie
authors.affiliation: Cefas Weymouth laboratory, The Nothe, Barrack Road, Weymouth DT4 8UB, UK.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Feist
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Merseyside L69 3BX, UK.
authors.forename: William M P
authors.initials: WMP
authors.lastname: Rowe
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Adams
authors.affiliation: Moredun Research Institute, Pentlands Science Park, Penicuik EH26 0PZ, UK.
authors.forename: Kim D
authors.initials: KD
authors.lastname: Thompson
mesh_terms: D000123:Acetyltransferases / Q000235:genetics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D045247:Chryseobacterium / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D016680:Genome, Bacterial / Q000235:genetics; D006460:Hemolysin Proteins / Q000096:biosynthesis; D006801:Humans; D008826:Microbial Sensitivity Tests; D017686:Oncorhynchus mykiss / Q000382:microbiology*; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D017262:Siderophores / Q000096:biosynthesis; D013753:Tetracycline Resistance / Q000235:genetics; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000494:pharmacology; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D006460:Hemolysin Proteins; D017262:Siderophores; D037521:Virulence Factors; D010649:Phenylalanine; C079641:phenylalanine-beta-naphthylamide; C035534:florfenicol; D000123:Acetyltransferases; C044496:streptothricin acetyltransferase; D015500:Chloramphenicol O-Acetyltransferase; D013839:Thiamphenicol
keywords: Chryseobacterium; Flavobacteriaceae; antimicrobial resistance; fish pathogen; horizontal gene transfer; virulence