First report of tetracycline-resistant Aeromonas veronii infection in Amur catfish (Silurus asotus) cultured in Korea

Abstract

Mass mortality in commercially cultured Amur catfish (Silurus asotus), showing symptoms of dermal ulcerations,occurred on a private farm in Mar 2019 in Korea. β-hemolytic bacteria were isolated from the ulcers and kidneys of the fish andidentified as Aeromonas veronii. The isolate was resistant to tetracycline and possessed cytotoxic heat-labile enterotoxin (aerolysin/hemolysin). We investigated the genetic determinants associated with tetracycline resistance, and the isolate has been confirmed tosimultaneously possess tetA and tetE genes. This is the first report on the occurrence of tetracycline-resistant A. veronii infectionrelated to mass mortality in commercially cultured Amur catfish in Korea.