Comparative analysis of Edwardsiella isolates from fish in the eastern United States identifies two distinct genetic taxa amongst organisms phenotypically classified as E. tarda

Matt J. Griffin, Sylvie M. Quiniou, Theresa Cody, Maki Tabuchi, Cynthia Ware, Rocco C. Cipriano, Michael J. Mauel, Esteban Soto Martinez

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Edwardsiella tarda, a Gram-negative member of the family Enterobacteriaceae, has been implicated in significant losses in aquaculture facilities worldwide. Here, we assessed the intra-specific variability of E. tarda isolates from 4 different fish species in the eastern United States. Repetitive sequence mediated PCR (rep-PCR) using 4 different primer sets (ERIC I & II, ERIC II, BOX, and GTG5) and multi-locus sequence analysis of 16S SSU rDNA, groEl, gyrA, gyrB, pho, pgi, pgm, and rpoA gene fragments identified two distinct genotypes of E. tarda (DNA group I; DNA group II). Isolates that fell into DNA group II demonstrated more similarity to E. ictaluri than DNA group I, which contained the reference E. tarda strain (ATCC #15947). Conventional PCR analysis using published E. tarda-specific primer sets yielded variable results, with several primer sets producing no observable amplification of target DNA from some isolates. Fluorometric determination of G+C content demonstrated 56.4% G+C content for DNA group I, 60.2% for DNA group II, and 58.4% for E. ictaluri. Surprisingly, these isolates were indistinguishable using conventional biochemical techniques, with all isolates demonstrating phenotypic characteristics consistent with E. tarda. Analysis using two commercial test kits identified multiple phenotypes, although no single metabolic characteristic could reliably discriminate between genetic groups. Additionally, anti-microbial susceptibility and fatty acid profiles did not demonstrate remarkable differences between groups. The significant genetic variation (<90% similarity at gyrA, gyrB, pho, phi and pgm; <40% similarity by rep-PCR) between these groups suggests organisms from DNA group II may represent an unrecognized, genetically distinct taxa of Edwardsiella that is phenotypically indistinguishable from E. tarda.

Original languageEnglish (US)
Pages (from-to)358-372
Number of pages15
JournalVeterinary Microbiology
Volume165
Issue number3-4
DOIs
StatePublished - Aug 30 2013
Externally publishedYes

Fingerprint

Edwardsiella
Edwardsiella tarda
Eastern United States
Fishes
DNA
organisms
fish
Polymerase Chain Reaction
Base Composition
Aquaculture
analytical kits
repetitive sequences
Nucleic Acid Repetitive Sequences
Enterobacteriaceae
Ribosomal DNA
Sequence Analysis
aquaculture
Fatty Acids
fatty acid composition
Genotype

Keywords

  • Blue catfish
  • Channel catfish
  • Edwardsiella tarda
  • Hybrid striped bass
  • Multilocus sequencing
  • PCR
  • Rep-PCR
  • Tilapia

ASJC Scopus subject areas

  • Microbiology
  • veterinary(all)

Cite this

Comparative analysis of Edwardsiella isolates from fish in the eastern United States identifies two distinct genetic taxa amongst organisms phenotypically classified as E. tarda. / Griffin, Matt J.; Quiniou, Sylvie M.; Cody, Theresa; Tabuchi, Maki; Ware, Cynthia; Cipriano, Rocco C.; Mauel, Michael J.; Soto Martinez, Esteban.

In: Veterinary Microbiology, Vol. 165, No. 3-4, 30.08.2013, p. 358-372.

Research output: Contribution to journalArticle

Griffin, Matt J. ; Quiniou, Sylvie M. ; Cody, Theresa ; Tabuchi, Maki ; Ware, Cynthia ; Cipriano, Rocco C. ; Mauel, Michael J. ; Soto Martinez, Esteban. / Comparative analysis of Edwardsiella isolates from fish in the eastern United States identifies two distinct genetic taxa amongst organisms phenotypically classified as E. tarda. In: Veterinary Microbiology. 2013 ; Vol. 165, No. 3-4. pp. 358-372.
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abstract = "Edwardsiella tarda, a Gram-negative member of the family Enterobacteriaceae, has been implicated in significant losses in aquaculture facilities worldwide. Here, we assessed the intra-specific variability of E. tarda isolates from 4 different fish species in the eastern United States. Repetitive sequence mediated PCR (rep-PCR) using 4 different primer sets (ERIC I & II, ERIC II, BOX, and GTG5) and multi-locus sequence analysis of 16S SSU rDNA, groEl, gyrA, gyrB, pho, pgi, pgm, and rpoA gene fragments identified two distinct genotypes of E. tarda (DNA group I; DNA group II). Isolates that fell into DNA group II demonstrated more similarity to E. ictaluri than DNA group I, which contained the reference E. tarda strain (ATCC #15947). Conventional PCR analysis using published E. tarda-specific primer sets yielded variable results, with several primer sets producing no observable amplification of target DNA from some isolates. Fluorometric determination of G+C content demonstrated 56.4{\%} G+C content for DNA group I, 60.2{\%} for DNA group II, and 58.4{\%} for E. ictaluri. Surprisingly, these isolates were indistinguishable using conventional biochemical techniques, with all isolates demonstrating phenotypic characteristics consistent with E. tarda. Analysis using two commercial test kits identified multiple phenotypes, although no single metabolic characteristic could reliably discriminate between genetic groups. Additionally, anti-microbial susceptibility and fatty acid profiles did not demonstrate remarkable differences between groups. The significant genetic variation (<90{\%} similarity at gyrA, gyrB, pho, phi and pgm; <40{\%} similarity by rep-PCR) between these groups suggests organisms from DNA group II may represent an unrecognized, genetically distinct taxa of Edwardsiella that is phenotypically indistinguishable from E. tarda.",
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