Antimicrobial Resistance and Improved Detection of Tenacibaculum in B.C. Atlantic salmon

Abstract

Tenacibaculum are a ubiquitously distributed marine bacterial genus with several species known to induce tenacibaculosis. Such outbreaks are responsible for significant annual mortality in Atlantic salmon necessitating antimicrobial intervention. With no standardized epidemiological cut-off values yet defined, this work establishes localized cut-off values for wildtype isolates of T. dicentrarchi determined to be ≤ 16 μg ml-1 for FFC over the four years assessed by both NRI analysis and ECOFFinder programs. The detection and characterization of Tenacibaculum isolates using 16s rDNA sequencing reveal significant limitations in species classification. Here, a novel high-throughput sequencing assay targeting the atpA gene was assessed using a series of mock communities in direct comparison to analogous 16s rDNA amplicons. Analysis reveals the atpA gene identifies all represented Tenacibaculum species, with sequence similarity between 55 and 80% to actual mock communities while the 16s gene identifies only 42% of represented species with similarity between 28 and 43%.