Genomic islands and mobilome demonstrate a potential pathogen, the Plesiomonas shigelloides, as in Nile tilapia (Oreochromis niloticus)

Abstract

Plesiomonas shigelloides is a common opportunistic pathogen of fish that may result in significant economic losses during outbreak periods. The infection is revealed by several clinical signs, including pericarditis, multifocal necrosis, hepatic atrophy, ulcerative lesions and other pathological changes, which may result in a reduction in the number of economically viable animals on fish farms. In humans, P. shigelloides infections are associated with diarrheic cases resulting from the consumption of contaminated food. These facts justify further study of the species pathogenicity, which is not yet well-established owing to the recent taxonomic classification. Considering the aforementioned information, the main goal of this research was to characterize the virulence and antimicrobial resistance factors present in four P. shigelloides strains isolated from aquatic organisms in Brazil. To gain a deeper understanding of the genomic characteristics of the subjects, the following methodology was employed: the genomic similarity of the strains was evaluated through the pyANI method; the phylogenomic evaluation was performed by OrthoFinder; GIPSy software was used for genomic island search; and PanViTa was employed to search for virulence and resistance factors. The results suggest the presence of multiple virulence factors (51) and antimicrobial resistance genes (12) in the genomes of the main isolates. This is the first genomic study of P. shigelloides exploring the potential pathogenicity in Nile tilapia in the northeast Brazil.