Antibiotics in agroecosystems: Introduction to the special section

The presence of antibiotic drug residues, antibiotic resistant bacteria, and antibiotic resistance genes in agroecosystems has become a significant area of research in recent years, and is a growing public health concern. While antibiotics are utilized for human medicine and agricultural practices, the majority of antibiotic use occurs in food animals where these drugs have historically been used for growth promotion, in addition to prevention and treatment of disease. The widespread use of antibiotics combined with the application of human and animal wastes to agricultural fields introduces antibiotic-related contamination into the environment. While overt toxicity in organisms directly exposed to antibiotic in agroecosystems is generally not an issue due to concentrations generally lower than therapeutic doses, the impacts of introducing antibiotic contaminants are unknown, and concerns have arisen about the health of humans, animals and ecosystems (One Health). Despite increases in research focused on the fate and occurrence of antibiotics and antibiotic resistance over the past decade, standard methodologies and practices for analyzing environmental samples are limited, and future research needs are becoming evident. To address these issues in detail, this special section was developed with a framework of five core review papers that address the (i) overall state of science of antibiotics and antibiotic resistance in agroecosystems with a causal model; (ii) chemical analysis of antibiotics in the environment; (iii) necessity for background and baseline data for studies of antibiotic resistance in agroecosystems with a decision-making tool to assist in designing research studies; as well as (iv) culture- and (v) molecular-based methods for analyzing antibiotic resistance in the environment. With a focus on the core review papers, this introduction to the special section summarizes the current state of science for analyzing antibiotics and antibiotic resistance in agroecosystems, while also discussing current knowledge gaps and future research priorities. This introduction also contains a glossary of terminologies that are commonly used throughout the special section. By defining these terminologies, it is hoped to provide a common language that clearly defines the linkages across the narratives of each paper

Tetracycline: production, waste treatment and environmental impact assessment

The frequent occurrence of pharmaceuticals in the aquatic environment requires an assessment of their environmental impact and their negative effects in humans. Among the drugs with high harmful potential to the environment are the antibiotics that reach the environment not only, as may be expected, through the effluents from chemical and pharmaceutical industries, but mainly through the sewage and livestock; because around 25 to 75% of the ingested drugs are excreted in unchanged form after the passage through the Gastro-Intestinal Tract. Tetracycline has high world consumption, representing a human consumption of about 23 kg/day in Brazil in 2007. At the moment, researches are being made to develop new tetracycline that incorporate heavy metals (Hg, Cd, Re, Pt, Pd) to their structures in order to increase their bactericidal effect. The conventional wastewater treatment plants are not able to degrade complex organic molecules to reduce their toxicity and improve their biodegradability. For this reason new technologies, i.e., the advanced oxidation processes, are being developed to handle this demand. The objectives of this study are to review the literature on the processes of obtaining tetracycline, presenting its waste treatment methods and evaluation of their environmental impact

Antibiotics in agroecosystems: Introduction to the special section

The presence of antibiotic drug residues, antibiotic resistant bacteria, and antibiotic resistance genes in agroecosystems has become a significant area of research in recent years, and is a growing public health concern. While antibiotics are utilized for human medicine and agricultural practices, the majority of antibiotic use occurs in food animals where these drugs have historically been used for growth promotion, in addition to prevention and treatment of disease. The widespread use of antibiotics combined with the application of human and animal wastes to agricultural fields introduces antibiotic-related contamination into the environment. While overt toxicity in organisms directly exposed to antibiotic in agroecosystems is generally not an issue due to concentrations generally lower than therapeutic doses, the impacts of introducing antibiotic contaminants are unknown, and concerns have arisen about the health of humans, animals and ecosystems (One Health). Despite increases in research focused on the fate and occurrence of antibiotics and antibiotic resistance over the past decade, standard methodologies and practices for analyzing environmental samples are limited, and future research needs are becoming evident. To address these issues in detail, this special section was developed with a framework of five core review papers that address the (i) overall state of science of antibiotics and antibiotic resistance in agroecosystems with a causal model; (ii) chemical analysis of antibiotics in the environment; (iii) necessity for background and baseline data for studies of antibiotic resistance in agroecosystems with a decision-making tool to assist in designing research studies; as well as (iv) culture- and (v) molecular-based methods for analyzing antibiotic resistance in the environment. With a focus on the core review papers, this introduction to the special section summarizes the current state of science for analyzing antibiotics and antibiotic resistance in agroecosystems, while also discussing current knowledge gaps and future research priorities. This introduction also contains a glossary of terminologies that are commonly used throughout the special section. By defining these terminologies, it is hoped to provide a common language that clearly defines the linkages across the narratives of each paper

Monoclonal antibody-based ELISA and colloidal gold-based immunochromatographic assay for streptomycin residue detection in milk and swine urine*

A protein conjugate of streptomycin (streptomycin-bovine serum albumin (BSA) conjugate) was prepared and used as immunogen to produce monoclonal antibodies (MAb). One hybridoma secreting anti-streptomycin MAb was obtained and then used to produce MAb. The MAb named 13H5 showed the 50% maximal inhibitory concentration (IC50) value of 4.65 ng/ml and the IC20 value of 0.21 ng/ml in phosphate buffered saline (PBS). At optimum conditions, an indirect competitive enzyme-linked immunosorbent assay (ELISA) and a colloidal gold-based immunochromatographic assay (CGIA) were developed and applied to detect streptomycin residues in milk and swine urine samples. The developed ELISA showed that the minimum detection limit was 2.0 and 1.9 ng/ml for milk and swine urine samples, respectively, without obvious cross-reactivity to other tested antibiotics except dihydrostreptomycin which gave a 118.32% cross reaction value. Milk and swine urine samples spiked with streptomycin at 10, 50, 100 and 200 ng/ml were analyzed by the established ELISA. The mean recovery of streptomycin was from 81.9% to 105.5% and from 84.3% to 92.2% for milk and swine urine, respectively. The optimized CGIA showed that the minimum detection limit was 20.0 ng/ml for milk and swine urine samples. The results of spiked analysis and specific analysis demonstrate that the CGIA could be applicable for screening milk and swine urine samples for the presence of streptomycin residues on-site. The established ELISA and CGIA allow the rapid, low-cost, and sensitive determination of streptomycin residues in food samples