Expression of AheABC Efflux System and Plasmid Profile of Aeromonas hydrophila Isolates from Farmed Nile Tilapia (Oreochromis niloticus) Mintra

Fifty Aeromonas hydrophila isolates from farmed Nile Tilapia were characterized for expression of AheABCmultidrug efflux system and plasmid profile. Thirty nine isolates (78%) expressed AheABC with production of 1.7 to221.3 folds more than AheB of A. hydrophila ATCC35654, the reference. This suggests that the AheABC efflux systemis not always constitutively expressed in the A. hydrophila clinical isolates. The isolates with less AheB expressionwere more resistant to antibiotics than those with high AheB expression. Seventeen isolates were found to carryplasmids that were arranged into 11 plasmid profiles. This is the first study of the AheABC efflux system in A.hydrophila isolates from fresh water fish, Nile Tilapia.