Explorando a patogenômica de isolados de aeromonas hydrophila provenientes do Rio São Francisco

Abstract

Bacterial infections are responsible for numerous economic losses in aquaculture. Among the species of concern, Aeromonas hydrophila is known to cause septicemia due to motile Aeromonas. Several studies worldwide have demonstrated the pathogenicity and multidrug resistance of this bacterium. However, despite the growing number of publications, studies using Brazilian isolates to investigate the pathogenicity of A. hydrophila through genomic characterization are still scarce. Therefore, this study aimed to conduct a pathogenetic study of A. hydrophila isolates from the São Francisco River, focusing specifically on pathogenicity and resistance. Initially, 34 A. hydrophila strains were isolated from Phractocephalus hemioliopterus (pirarara), Lophiosilurus alexandri (pacamã), Oreochromis niloticus (Nile tilapia), Dendrocephalus brasiliensis (freshwater brine shrimp), and water. Next-generation sequencing of these isolates was performed using the HiSeq 2500 platform, and the quality of the raw data was assessed using FastQC. Subsequently, assembly and annotation were performed. The genomes were confirmed as A. hydrophila through nucleotide identity calculation and phylogenomic analysis. The presence of genomic islands was investigated, as well as a search for pathogenicity and antibiotic resistance genes. The phylogenomic study revealed clusters among the study strains similar to those identified by the ANI calculation, demonstrating their proximity. Furthermore, pathogenicity and resistance genes to more than one class of antibiotics were found in all 34 sequenced genomes. Furthermore, the presence of pathogenicity islands was observed in almost all genomes. Heavy metal resistance genes were also observed. These findings reinforce the genomic plasticity of A. hydrophila, previously highlighted by other studies. The evidence found in the study's genomes raises genuine concerns about controlling bacterial infections and the use of antibiotics in aquaculture systems, as well as demonstrating the importance of genomic monitoring of pathogens in preventing outbreaks.