Location: Warmwater Aquaculture Research UnitTitle: Discriminatory PCR assays differentiate between Edwardsiella tarda and Edwardsiella tarda-like species and identify the predominant species in catfish aquaculture Author
Submitted to: Annual Eastern Fish Health Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 4/6/2013
Publication Date: 4/29/2013
Citation: Griffin, M., Ware, C., Quiniou, S., Steadman, J., Esteban, S. 2013. Discriminatory PCR assays differentiate between Edwardsiella tarda and Edwardsiella tarda-like species and identify the predominant species in catfish aquaculture. Annual Eastern Fish Health Workshop. P.42. Interpretive Summary:
Technical Abstract: Recently a new taxa of Edwardsiella, phenotypically similar to E. tarda, has been described from fishes of Europe and Asia. Based on extensive genetic and phenotypic characterization, researchers have determined this new strain does not belong to any established taxa within the genus Edwardsiella and have proposed the adoption of a new taxon, E. piscicida. Similarly, a study here in the United States has also identified two genetically distinct taxa within the group of organisms traditionally classified as E. tarda. Using GyrB sequencing and repetitive sequence mediated PCR (rep-PCR) we have confirmed the existence of these two genetically distinct taxa and have identified E. piscicida from fish in the southeastern United States. In addition, we have developed a discriminatory PCR that differentiates between E. tarda, E. ictaluri and two genetic variants of E. piscicida. Using this novel PCR assay, we conducted a survey of bacterial specimens isolated from diseased catfish at the Aquatic Research and Diagnostic Laboratory (National Warmwater Aquaculture Center, Stoneville, MS) from 2007-2012. All isolates were identified as E. tarda upon initial collection, of which the majority were misclassified E. piscicida. This supports previous claims from Europe and Asia that E. piscicida may be more commonly associated with diseased fish than E. tarda.