Accumulation of trimethoprim, sulfamethoxazole, and N-acetylsulfamethoxazole in fish and shrimp fed medicated Artemia franciscana.

In a previous paper (H.J. Nelis, P. Léger, P. Sorgeloos, and A. P. De Leenheer, Antimicrob. Agents Chemother. 35:2486-2489, 1991) it was reported that two selected antibacterial agents, i.e., trimethoprim and sulfamethoxazole, can be efficiently bioencapsulated in nauplii of the brine shrimp Artemia franciscana for administration to fish. This follow-up study showed that larvae of the sea bass and the turbot as well as postlarvae of the white shrimp accumulate the therapeutic agents in high quantities when fed medicated A. franciscana. To monitor their levels as a function of time, the liquid chromatographic method originally developed for the analysis of A. franciscana was modified with respect to chromatography, internal standardization, and sample pretreatment. The levels of trimethoprim ranged from 1 to 7 micrograms/g (sea bass), 1 to 13 micrograms/g (turbot), and 4 to 38 micrograms/g (white shrimp). The corresponding values for sulfamethoxazole were 0.3 to 4 micrograms/g (sea bass), 1 to 42 micrograms/g (turbot), and 4 to 35 micrograms/g (white shrimp). Only the two fish species, unlike the shrimp, metabolized the latter to N-acetylsulfamethoxazole (concentration range, 1 to 10 micrograms/g). These data suggest the potential of the bioencapsulation of therapeutic agents in live food as a tool to control infectious diseases in aquaculture. A preliminary challenge test also confirmed the in vivo efficacy of this approach.