Acinetobacter johnsonii: an Emerging Pathogen for Cultured Blunt Snout Bream Megalobrama amblycephala

Abstract

Bacteriosis has caused significant economic losses in farmed blunt snout bream Megalobrama amblycephala. Only scarce information is available on Acinetobacter johnsonii as a possible causal agent in M. amblycephala. In this study, a virulent strain temporarily named BY3, was isolated from diseased bream, identified phenotypically and molecularly as A. johnsonii. Phylogenetic trees of 16S rRNA and gyrB gene sequences were constructed to examine the taxonomic position of isolate BY3 and compare it to other known isolates. When screened against a range of common veterinary antibiotics, isolate BY3 has not shown resistance to florfenicol, neomycin, and sulfisoxazole antibiotics in aquaculture. To the best of our knowledge, this is the first report of A. johnsonii infection in farmed blunt snout bream.