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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #386593
Research Project: Mississippi Center for Food Safety and Post-Harvest Technology

Location: Warmwater Aquaculture Research Unit

Title: Characterization of a Novel Conjugative Plasmid in Edwardsiella piscicida Strain MS-18-199

Author
item ABDELHAMED, HOSSAM - Mississippi State University
item RAMACHANDRAN, RESHMA - Mississippi State University
item OZDEMIR, OZAN - Mississippi State University
item Waldbieser, Geoffrey - Geoff
item LAWRENCE, MARK - Delta Health Alliance

Submitted to: Frontiers in Cellular and Infection Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Catfish aquaculture in the US Southeastern states is the most important aquaculture in the United States. Edwardsiella piscicida is a pathogenic bacterium responsible for significant losses in catfish. This manuscript explored the mechanisms of resistance in E. piscicida strain MS-18-199 recovered from a diseased hybrid catfish from East Mississippi and showed resistance to florfenicol. To our knowledge, this is the first detection of a conjugative plasmid in E. piscicida in the United States. Knowledge regarding the molecular mechanisms of AMR in aquaculture is important for antimicrobial stewardship.

Technical Abstract: BACKGROUND: A multidrug resistant strain of Edwardsiella piscicida strain MS-18-199 has been recovered from moribund hybrid catfish submitted to Aquatic Diagnostic Laboratories at College of Veterinary Medicine Mississippi State University. The mechanisms that drive resistance in this isolate is unclear. In this manuscript, we described the genetic feature of a large conjugative plasmid identified in E. piscicida. Moreover, we evaluated plasmid mobility and stability. METHOD: Genomic DNA was extracted from E. piscicida strain MS-18-199, and subjected to whole genome sequencing (WGS) and assembly using a combination of long (Oxford Nanopore) and short (Illumina) reads. Conjugation Experiment was performed to evaluate the plasmid mobility. Plasmid copy numbers were determined using quantitative real-time PCR. RESULTS: The genome of strain MS-18-199 revealed a novel plasmid named pEPMS-18199 that contains several antimicrobial resistance (AMR) elements/genes. Results from mobilization and stability experiments revealed that pEPMS-18199 is highly stable in the host cell and could be transferred to Escherichia coli and Edwardsiella ictaluri by conjugation. CONCLUSION: This study describes for the first time a high molecular weight conjugative plasmid carrying AMR genes in an E. piscicida isolate in the United States. Careful and prudent use of antimicrobials in aquaculture production could help to reduce the persistence and propagation of such plasmid. Also, conducting antimicribial sensitivity assays before antimicrobial therapy is strongly recommended.