Pathogenicity, resistance patterns, virulence traits, and resistance genes of re-emerging extensively drug-resistant (XDR) Aeromonas veronii in Oreochromis niloticus

Aeromonas veronii, a threatening fish pathogen, is implicated in food-borne infections in humans, contributing to substantial economic losses in the aquaculture sector. To examine the occurrence, resistance profiles, 16SrRNA sequence analysis, virulence-determinant and resistance genes, and pathogenicity of A. veronii isolated from Nile tilapia (Oreochromis niloticus), almost 150 fish weighing 75 ± 10 g (apparently healthy; n = 50 and moribund fish; n = 100) were collected from commercial farms in Ismailia Governorate, Egypt. Subsequently, the clinical, post-mortem, and bacteriological examinations were carried out. The overall prevalence of A. veronii in the collected O. niloticus was 18.6