Expression of AheABC efflux system and plasmid profile of aeromonas hydrophila isolates from farmed Nile Tilapia (Oreochromis niloticus)

Abstract

Fifty Aeromonas hydrophila isolates from farmed Nile Tilapia were characterized for expression of AheABC multidrug efflux system and plasmid profile. Thirty nine isolates (78%) expressed AheABC with production of 1.7 to 221.3 folds more than AheB of A. hydrophila ATCC35654, the reference. This suggests that the AheABC efflux system is not always constitutively expressed in the A. hydrophila clinical isolates. The isolates with less AheB expression were more resistant to antibiotics than those with high AheB expression. Seventeen isolates were found to carry plasmids 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.