PERSISTENCE OF ANTIBACTERIAL AGENTS IN MARINE-SEDIMENTS

The persistence of the antibacterial agents oxytetracycline chloride (OTC), oxolinic acid (OA), flumequine (FLU),sarafloxacin (SAR), florfenicol (FLO), sulfadiazine (SDZ) and trimethoprim (TRM) were compared in marine sediments. Polyethylene boxes were filled with sediment, the antibacterial compounds added and placed on the sea bed at approximately 15 m depth for a period of 180-230 days, Sediment cores were collected by a diver and analyzed for residues of the antibacterials in four depth intervals from 1 to 7 cm. OTC and the quinolones OA, F and SAR were found to be very persistent in the sediment. In the deeper layer of the sediment the initial concentrations of these compounds were present after 180 days, whereas the residues in the top layer of the sediment depurated more rapidly. The depuration of these substances from the sediment is most probably due to leaching and redistribution rather than degradation. The quinolones were found to adsorb to sediment. SDZ and TRM were less persistent than the quinolones; however, the estimated half-life in the deepest layer (6-7 cm) was approximately 90 days for both substances. The concentration of FLO decreased rapidly in the sediment with a calculated half-life of 4.5 days, and a metabolite, florfenicol amine, was identified in the sediment.