In Silico Characterization of Resistance and Virulence Genes in Aeromonas jandaei Strains Isolated from Oreochromis niloticus in Brazil

Understanding the genetic characteristics of <i>Aeromonas jandaei</i> in Brazilian aquaculture is crucial for developing effective control strategies against this fish pathogen. The present study conducted a genomic analysis of Brazilian <i>A. jandaei</i> strains with the objective of investigating their virulence potential and resistance profiles. Four Brazilian isolates were subjected to sequencing, and comparative genomic analyses were conducted in conjunction with 48 publicly available <i>A. jandaei</i> genomes. The methods employed included quality assessment, de novo assembly, annotation, and analyses of antimicrobial resistance and virulence factors. The results demonstrated the presence of fluoroquinolone resistance genes within the core genome. Notably, these antibiotics are not authorized for use in aquaculture in Brazil, suggesting that their resistance determinants may originate from other selective pressures or horizontal gene transfer unrelated to aquaculture practices. The analysis identified significant virulence mechanisms, including T2SS, T3SS, and notably T6SS (<i>vgrG3</i> gene), which was more prevalent in Brazilian isolates. Additionally, genes associated with motility, adhesion, and heavy metal resistance were identified. These findings highlight the enhanced adaptability of Brazilian <i>A. jandaei</i> strains and raise concerns about antimicrobial resistance in aquaculture, emphasizing the need for improved regulatory oversight and control strategies.