The aquaculture industry has had a sharp increase worldwide in the last years. Many classes of antibiotics are used in aquaculture t8o treat infections caused by a number of bacterial pathogens and also as a growth promoter. However, environmental contamination and bacterial resistance may be caused by these intense uses. A fast and sensitive on-line LC-ESI-MS/MS method was developed and validated for simultaneous assessment of 12 antibiotics of different classes in surface water and sediment, a conventional LC-MS/MS method for fish, and antimicrobial resistance of bacteria of fish was evaluated. The water phase of sediment and the water samples was injected in the analytical system that consisted of a pre-concentration with an automated liquid sampler fitted with a 900 �L injection loop, a valve used to switch between the load or elution modes; a pair of pumps, and MS/MS system. The fish extract was cleaned by chemical filtration by Captiva cartridges. Sulfadimethoxine-d6 was used as internal standard to obtain more reliable results. The samples were collected from 4 fish farms located in the hydroelectric dam in Parana River in Brazil. Four samplings were made during a year. After validation of the methods in according to the European Union Decision 2002/657/EC, they were applied in the analysis of 144 samples of each matrix. Residues of oxytetracycline, tetracycline, chlortetracycline, was found in sediment and oxytetracycline, tetracycline, and florfenicol have been identified in the samples of water and fish and bacteria were resistant to quinolones, tetracyclines, sulfonamides in 36 strains and antibiotic resistance index (ARI) values ranged between 0 and 0.86, that is, strains with a sensitivity of 100% of the tested antimicrobials and others resistant to 86% of the tested antimicrobials. More restrictive attitude is necessary towards the intensive use of antimicrobials in fish farming.

Antimicrobial residue in water, sediment, and fish of the cage farming and bacteria resistance

248th National Meeting (2014)

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