Genomics of Re-Emergent Aeromonas salmonicida in Atlantic Salmon Outbreaks

• Published in: Microorganisms
• Main Authors: Marcos Godoy, Marco Montes de Oca, Rudy Suarez, Alexis Martinez, Juan Pablo Pontigo, Diego Caro, Karina Kusch, Yoandy Coca, Harry Bohle, Sion Bayliss, Molly Kibenge, Frederick Kibenge
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: furunculosis; Aeromonas salmonicida; Salmo salar; genomic diversity; Biology (General); QH301-705.5; Atlantic salmon
• Online Access: https://doi.org/10.3390/microorganisms12010064; https://doaj.org/article/7ced173b4e334b04a08cfa546f28fd06

Furunculosis, caused by Aeromonas salmonicida , poses a significant threat to both salmonid and non-salmonid fish in diverse aquatic environments. This study explores the genomic intricacies of re-emergent A. salmonicida outbreaks in Atlantic salmon ( Salmo salar ). Previous clinical cases have exhibited pathological characteristics, such as periorbital hemorrhages and gastrointestinal abnormalities. Genomic sequencing of three Chilean isolates (ASA04, ASA05, and CIBA_5017) and 25 previously described genomes determined the pan-genome, phylogenomics, insertion sequences, and restriction-modification systems. Unique gene families have contributed to an improved understanding of the psychrophilic and mesophilic clades, while phylogenomic analysis has been used to identify mesophilic and psychrophilic strains, thereby further differentiating between typical and atypical psychrophilic isolates. Diverse insertion sequences and restriction-modification patterns have highlighted genomic structural differences, and virulence factor predictions can emphasize exotoxin disparities, especially between psychrophilic and mesophilic strains. Thus, a novel plasmid was characterized which emphasized the role of plasmids in virulence and antibiotic resistance. The analysis of antibiotic resistance factors revealed resistance against various drug classes in Chilean strains. Overall, this study elucidates the genomic dynamics of re-emergent A. salmonicida and provides novel insights into their virulence, antibiotic resistance, and population structure.