Use of Bacteriophage to Control Experimental Aeromonas hydrophila Infection in Tilapia (Oreochromis niloticus)

BACKGROUND AND OBJECTIVE: Antibiotics have been used to treat Aeromonas hydrophila infections in fish farming. However, their extensive uses can cause many negative effects including the development of drug-resistant bacterial strains. The main objective of this study was to find an alternative to antibiotics to inhibit A. hydrophila both in vitro and in vivo. MATERIALS AND METHODS: A bacteriophage infecting A. hydrophila was isolated from a fish a pond water sample. It was classified based on its genome type studied by enzymatic digestion and morphology investigated by transmission electron microscopy. Its ability to control experimental A. hydrophila infection in tilapia (Oreochromis niloticus) was examined by feeding tilapia with fish diets supplemented with different titers of the bacteriophage. RESULTS: A bacteriophage specific to Aeromonas hydrophila UR1 designated PAh4 was isolated and classified as a member of the family Myoviridae. When tilapia experimentally infected with A. hydrophila at the median lethal dose (3.16×105 CFU per fish) were fed the fish diets supplemented with the bacteriophage PAh4 at doses ranging from 105-108 PFU g-1 of diet, the diets could reduce the mortality rate of infected tilapia in a dose-dependent manner. CONCLUSION: The bacteriophage PAh4 can be used as an alternative to antibiotics to control A. hydrophila infection in tilapia.