Determination of chlortetracycline residues, antimicrobial activity and presence of resistance genes in droppings of experimentally treated broiler chickens
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Tetracyclines are important antimicrobial drugs for poultry farming that are actively excreted via feces and urine. Droppings are one of the main components in broiler bedding, which is commonly used as an organic fertilizer. Therefore, bedding becomes an unintended carrier of antimicrobial residues into the environment and may pose a highly significant threat to public health. For this depletion study, 60 broiler chickens were treated with 20% chlortetracycline (CTC) under therapeutic conditions. Concentrations of CTC and 4-epi-CTC were then determined in their droppings. Additionally, this work also aimed to detect the antimicrobial activity of these droppings and the phenotypic susceptibility to tetracycline in E. coli isolates, as well as the presence of tet(A), tet(B), and tet(G) resistance genes. CTC and 4-epi-CTC concentrations that were found ranged from 179.5 to 665.8 mu g/kg. Based on these data, the depletion time for chicken droppings was calculated and set at 69 days. All samples presented antimicrobial activity, and a resistance to tetracyclines was found in bacterial strains that were isolated from these samples. Resistance genes tet(A) and tet(B) were also found in these samples.
This work was supported by the University of Chile [Project U Inicia 2013] and by the IAEA Research contract 22180, under the Coordinated Research Project D52041. The authors appreciate the collaboration of Mr. Rodrigo Gambra in the translation of this manuscript. The authors state that they did not receive specific funds for covering the costs to publish as open access.
Artículo de publicación ISI
Quote ItemMolecules 2018, 23,1264
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