Characterization of Isolates from Ornamental Fish: Species, Virulence Genes, and Antimicrobial Susceptibility.

This study aimed to characterize 300 spp. strains isolated from 123 ornamental fish of 32 different species presenting with septicemia, skin lesions, and/or eye lesions. Within the 300 strains, 53.0% were identified as , 41.3% as , and 5.7% as . Among the six virulence genes investigated, the most frequent were (90.3%) and (79.3%). More than 50% of strains were positive for all the studied genes. A total of 30 virulence profiles were identified, with the five main profiles identified comprising 75% of strains. Only five strains were negative for all genes and were identified as and . The antimicrobial susceptibility profile was performed for 234 strains, with sulfonamides presenting more than 50% of the resistance rates. Susceptibility was observed mainly for cephalosporins, aminoglycosides, chloramphenicol and piperacillin-tazobactam. Multidrug resistance was detected in 82.5% of the studied strains, including with 100% multidrug resistance, and with 90.9% multidrug resistance. The SE-AFLP analysis resulted in 66 genotypes of , 118 genotypes of , and 14 genotypes of , demonstrating the greater heterogeneity of and A. . However, no direct correlation was observed between the genotypes and the strains' origins or virulence and resistance profiles.