Development, validation and application of an ultra high performance liquid chromatographic-tandem mass spectrometric method for the simultaneous detection and quantification of five different classes of veterinary antibiotics in swine manure

A sensitive lateral flow immunoassay relying on time-resolved fluorescent microspheres immune probe for determination of ceftiofur and its metabolite

Ceftiofur (CEF) is an antimicrobial agent with high efficiency and low toxicity, desfuroylceftiofur is its main metabolite, but they are also have potential harm to human health. In this study, ceftiofur was combined with carrier proteins to get artificial antigens. A specific antibody (pAb) against CEF and desfuroylceftiofur was prepared. A sensitive and rapid paper-based sensor relying on time-resolved fluorescent microspheres (TRFMs) immune probes was developed, which were time-resolved fluorescent immunochromatographic strips (TRFMs-LFIA). The concentrations of T line and C line, activated pH, antibody volume and probe volume were optimized. Quantitative limits of detection (qLODs) of TRFMs-LFIA for CEF and desfuroylceftiofur were 0.97 ng/mL and 0.41 ng/mL, respectively. And 50 % inhibiting concentrations (IC50) were 12.92 ng/mL and 12.58 ng/mL, respectively. Pretreatment procedures of real samples were simple and rapid. Detection time of TRFMs-LFIA strip was 15 min. Qualitative analysis of CEF and desfuroylceftiofur was achieved under a UV light, quantitative analysis was implemented with a fluorescent immunoassay analyzer. The average recovery rates ranged from 91.4 % to 107.7 % and corresponding coefficients of variation (CV) was 1.5%-9.7 %. Concentration levels of artificially-spiked samples were measured by TRFMs-LFIA and compared with detection results of High performance liquid chromatography (HPLC), which showed a good accordance. These results indicated that the proposed assay can provide an effective strategy for on-site detection of CEF and desfuroylceftiofur simultaneously.

Protecting the Last Line of Defense: Analytical Approaches for Sample Preparation and Determination of the Reserve Group of Antibiotics in the Environment

Drug resistance in microorganisms is a serious threat to life and health due to the limited number of antibiotics that show efficacy in treating infections and the difficulty in discovering new compounds with antibacterial activity. To address this issue, the World Health Organization created the AWaRe classification, a tool to support global and national antimicrobial stewardship programs. The AWaRe list categorizes antimicrobials into three groups - Access, Watch, and Reserve - according to their intended use. The Reserve group comprises "last resort" medicines used solely for treating infections caused by bacterial strains that are resistant to other treatments. It is therefore necessary to protect them, not only by using them as prudently as possible in humans and animals, but also by monitoring their subsequent fate. Unmetabolized antibiotics enter the environment through hospital and municipal wastewater or from manure, subsequently contaminating bodies of water and soils, thus contributing to the emergence and spread of antibiotic resistance. This article presents a review of determination methods for the Reserve group of antimicrobials in water, wastewater, and manure. Procedures for extracting and determining these substances in environmental samples are described, showing the limited research available, which is typically on a local level.

Detection of antibiotic residues in groundwater with a validated multiresidue UHPLC-MS/MS quantification method

The occurrence of antibiotic residues in the environment has received considerable attention because of their potential to select for bacterial resistance. The overuse of antibiotics in human medicine and animal production results in antibiotic residues entering the aquatic environment, but concentrations are currently not well determined. This study investigates the occurrence of antibiotics in groundwater in areas strongly related to agriculture and the antibiotic treatment of animals. A multiresidue method was validated according to EU Regulation 2021/808, to allow (semi-)quantitative analysis of 78 antibiotics from 10 different classes: β-lactams, sulfonamides, tetracyclines, lincosamides, amphenicols, (fluoro)quinolones, macrolides, pleuromutilins, ansamycins and diaminopyrimidines using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method was used to test different storage conditions of these water samples during a stability study over a period of 2 weeks. Sulfonamides, lincosamides and pleuromutilins were the most stable. Degradation was most pronounced for β-lactam antibiotics, macrolides and ansamycins. To maintain stability, storage of samples at -18 °C is preferred. With the validated method, antibiotic residues were detected in groundwater, sampled from regions associated with intensive livestock farming in Flanders (Belgium). Out of 50 samples, 14% contained at least one residue. Concentrations were low, ranging from < LOD to 0.03 μg/L. Chloramphenicol, oxolinic acid, tetracycline and sulfonamides (sulfadiazine, sulfadoxine, sulfamethazine and sulfisoxazole) were detected. This study presents a new method for the quantification of antibiotic residues, which was applied to investigate the presence of antibiotic residues in groundwater in Flanders.

Residues of veterinary antibiotics in manures from pig and chicken farms in a context of antimicrobial use reduction by implementation of health and welfare plans

The use of antibiotics in food-producing animals can induce the presence of residual substances in manure, which are then released into the environment and may contribute to soil and groundwater contamination. During the on-farm implementation of strategies to improve animal health and welfare in chicken and pig farms, the consequences of antibiotic use were evaluated in terms of the occurrence and levels of antibiotic residues in manure. A set of 35 broiler farms from Cyprus, Greece, the Netherlands and 40 pig farms from France and Italy provided a total of 350 manure samples. The primary objective was to develop a specific LC/MS/MS method capable of quantifying antibiotic residues in both types of manure. The method was able to detect fifteen antibiotics belonging to nine classes, with validated limits of quantification of 10-20 μg/kg, and accuracies ranging from 81% to 138%. With the exception of amoxicillin, which was never detected in any manure, all antibiotics used were detected in manure from treated animals with typical concentrations ranging from 10 to 99198 μg/kg for both chickens and pigs. The occurrence of residual antibiotics was higher in chicken than in pig manure, especially for fluoroquinolones and doxycycline which were detected in 89% and 100% of the chicken manure, respectively, and in 28% of the pig manure. The impact of the health plans on the antibiotic load manure was assessed by measuring for each farm the ratio of the sum of all antibiotic concentrations measured after and before the implementation of the plan. The results showed that, in addition to the frequency of treatments, the class of antibiotic used is an important factor to consider as it strongly influences the stability/instability of the compounds, i.e. their ability to persist in the manure of food-producing animals.

Characteristics of antimicrobial residues in manure composts from swine farms: Residual patterns, removal efficiencies, and relation to purchased quantities and composting methods in Japan

Present study provides first comprehensive results on the residual levels of 19 antimicrobial (AM) residues in 12 Japanese swine manure composting facilities that use open or enclosed types of treatment methods. Tilmicosin (14000 μg/kg d.w.) and tiamulin (15000 μg/kg d.w.) were present in the highest concentrations in manure composts. Morantel (MRT) had the highest detection frequency (100%) in compost, suggesting its ubiquitous usage and resistance to degradation during composting. Sulfamethoxazole had low detection frequencies and concentrations, likely due to limited partitioning to the solid phase. A positive correlation (p < 0.05) between purchasing quantities and residue levels in manure composts was detected for fluoroquinolones (FQs). The removal efficiencies of AMs in enclosed-type facilities were lower and more inconsistent than those in open-type facilities. Tetracyclines (TCs), lincomycin, and trimethoprim were easily removed from open-type facilities, whereas FQs and MRT persisted in both facilities. After discontinuing the usage of oxytetracycline (OTC), TCs concentrations reduced drastically in input materials, remained pseudo-persistent in composts for up to 4 months, suggesting a time lag for composting and were not detected (<10 µg/kg) after 4 months of OTC withdrawal. This study emphasizes on the effectiveness of manure composting methods in reducing AM residues in swine waste.

Gold@Carbon Quantum Dots Nanocomposites Based Two-In-One Sensor: A Novel Approach for Sensitive Detection of Aminoglycosides Antibiotics in Food Samples

Antibiotics are life-saving drugs for humans, but their unwanted use leads to antibacterial resistance (ABR) and causes serious health problems. The excess of these antibiotics entered to the food chain and caused food contamination. Here, Au@CQDs nanocomposites (NCs) was used as a two-in-one sensor to detect two antibiotics. The color change of AuNCs and fluorescence resonance energy transfer are two distance-dependent phenomena used as sensing mechanisms. In the sensing process, Au@CQDs NCs change their color, enhancing the fluorescence intensity of NCs in the presence of Gentamicin (GENTA) and Kanamycin (KMC) antibiotics. The limit of detection of 116 nM and 133 nM for GENTA and 195 nM and 120 nM for KMC have been achieved with colorimetric and fluorimetric readout, respectively. The practicality of the reported sensor was evaluated in real spiked samples and showed excellent recovery efficiency. Therefore this two-in-one sensor can be used for the food monitoring system.

Occurrence and prevalence of antibiotic resistance genes in apple orchard after continual application of anaerobic fermentation residues of pig manure

Fermented organic fertilizers made from pig manure contaminated with antibiotics are widely used in fruit tree production. However, their effects on the residual antibiotics and the spread of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in apple orchards are still largely unknown. In the present study, we detected 100 ARGs and 10 MGEs that were transferred from pig manure to an apple orchard. Compared with the original pig manure, significantly greater concentrations of tetracycline, chlortetracycline, oxytetracycline, sulfadiazine, and salfamethyldiazine were observed in anaerobic fermentation residues of the pig manure. The total relative abundance levels of ARGs on the apple pericarp surface, in the orchard soil treated with biogas slurry, and in the orchard soil treated with biogas residue were 122.5, 5.2, 1.4 times higher than those in pristine soil, respectively, which were primarily attributed to the increase in the relative abundance of some ARG subtypes, including blaCTX-M, blaTEM, ermC, sul2, tetO, vgaB, and vgb. Long-term biogas slurry and biogas residue applications to orchard soil enriched bioaccumulation of 10 ARGs and 1 MGEs on the apple pericarp surface with 67.98 the highest factor. This research indicates that the application of anaerobic fermentation residues of pig manure promoted the spread of ARGs in the soil and fruits and increased the level of ARG pollution in the orchard. Results of this study highlight the importance of assessing the ecological safety of organic fertilizers from the perspective of ARGs and indicate that efforts should be devoted to further reducing ARG levels in pig manure before its application to farmland.

Identification and Quantification of 29 Active Substances by HPLC-ESI-MS/MS in Lyophilized Swine Manure Samples

Veterinary drugs are frequently employed to treat and prevent diseases in food-producing animals to improve animal health and to avoid the introduction of microorganisms into the food chain. The analysis of the presence of pharmaceutical residues in animal manure could help to evaluate the legal and illegal practices during food production without harming the animals and to correctly manage manure when it is going to be applied as a fertilizer. This article describes a method for the simultaneous analysis of 29 active substances, mostly antibiotics and antiparasitic agents. Substances were extracted from lyophilized manure with a methanol:McIlvaine solution and analyzed with HPLC-ESI-MS/MS and a C18 HPLC column. The method was validated following European guidelines, the achieved trueness was between 63 and 128% (depending on the analytes), and the linearity was between 100 and 1500 µg/kg. The applicability of the method was demonstrated in 40 manure samples collected from pig farms where tetracycline was quantified in 7.5% of the samples. These results show the viability of this non-invasive method for the control of the legal and illegal administration of pharmaceuticals in food-producing animals.

Quantifying Antibiotic Distribution in Solid and Liquid Fractions of Manure Using a Two-Step, Multi-Residue Antibiotic Extraction

Antibiotic distribution and analysis within liquid and solid fractions of manure are highly variable due to each compound’s respective physiochemical properties. This study developed and evaluated a uniform method extracting 10 antibiotics from 4 antibiotic classes (tetracycline, sulfonamides, macrolides, and β-lactam) from unprocessed manure, solid−liquid separated manure, and composted solids. Through systematic manipulation of previously published liquid chromatography tandem mass spectrometry methods; this study developed an extraction protocol with optimized recovery efficiencies for varied manure substrates. The method includes a two-step, liquid-solid extraction using 10 mL of 0.1 M EDTA-McIlviane buffer followed by 10 mL of methanol. Antibiotics recoveries from unprocessed manure, separated liquids, separated solids, and heat-treated solids using the two-step extraction method had relative standard deviations < 30% for all but ceftiofur. Total antibiotic recoveries were 67−131% for tetracyclines, 56% for sulfonamide, 49−53% for macrolides, and 1.3−66% for β-lactams. This is the first study to use one protocol to assess four classes of antibiotics in liquid and solid manure fractions. This study allowed for more precise risk assessment of antibiotic transport in manure waste stream applied to fields as a liquid or solid compost.

Antibiotic resistant genes in the environment-exploring surveillance methods and sustainable remediation strategies of antibiotics and ARGs

Antibiotic Resistant Genes (ARGs) are an emerging environmental health threat due to the potential change in the human microbiome and selection for the emergence of antibiotic resistant bacteria. The rise of antibiotic resistant bacteria has caused a global health burden. The WHO (world health organization) predicts a rise in deaths due to antibiotic resistant infections. Since bacteria can acquire ARGs through horizontal transmission, it is important to assess the dissemination of antibioticresistant genes from anthropogenic sources. There are several sources of antibiotics, antibiotic resistant bacteria and genes in the environment. These include wastewater treatment plants, landfill leachate, agricultural, animal industrial sources and estuaries. The use of antibiotics is a worldwide practice that has resulted in the evolution of resistance to antibiotics. Our review provides a more comprehensive look into multiple sources of ARG's and antibiotics rather than one. Moreover, we focus on effective surveillance methods of ARGs and antibiotics and sustainable abiotic and biotic remediation strategies for removal and reduction of antibiotics and ARGs from both terrestrial and aquatic environments. Further, we consider the impact on public health as this problem cannot be addressed without a global transdisciplinary effort.

Occurrence and risk assessment of five kinds of antimicrobial in mattress on swine farm use ectopic fermentation systems in Zhejiang Province

Mattress is among the main products of ectopic fermentation system (EFS); however, the research on the data of antimicrobial residues in the mattress of EFS and risk assessments of mattress have not been conducted. This study involved a scale survey to assess the levels and distributions of 54 antimicrobial residues, including 4 tetracyclines, 19 quinolones, 22 sulfonamides, 3 amphenicols, and 6 macrolides in mattress on 12 swine farms that use ectopic fermentation systems (EFS) in Zhejiang Province. A total of 25 antimicrobials were detected in mattress, and the total residue amount of antimicrobial in mattress samples of each farm was 0.77-28.2 g/T. Chlortetracycline had the highest contribution rate, and the residue amount of antimicrobial in mattress is not entirely determined by the start-up time of EFS but is related to the use of feed containing antimicrobial, medication habits, the level of mattress management, and maintenance methods of EFS. The risk assessments of antimicrobial in the mattress were carried out. The results show that the risk of using mattress of EFS for soil is low.

Insights into the impact of manure on the environmental antibiotic residues and resistance pool

The intensive use of antibiotics in the veterinary sector, linked to the application of manure-derived amendments in agriculture, translates into increased environmental levels of chemical residues, AR bacteria (ARB) and antibiotic resistance genes (ARG). The aim of this review was to evaluate the current evidence regarding the impact of animal farming and manure application on the antibiotic resistance pool in the environment. Several studies reported correlations between the prevalence of clinically relevant ARB and the amount and classes of antibiotics used in animal farming (high resistance rates being reported for medically important antibiotics such as penicillins, tetracyclines, sulfonamides and fluoroquinolones). However, the results are difficult to compare, due to the diversity of the used antimicrobials quantification techniques and to the different amounts and types of antibiotics, exhibiting various degradation times, given in animal feed in different countries. The soils fertilized with manure-derived products harbor a higher and chronic abundance of ARB, multiple ARG and an enriched associated mobilome, which is also sometimes seen in the crops grown on the amended soils. Different manure processing techniques have various efficiencies in the removal of antibiotic residues, ARB and ARGs, but there is only a small amount of data from commercial farms. The efficiency of sludge anaerobic digestion appears to be dependent on the microbial communities composition, the ARB/ARG and operating temperature (mesophilic vs. thermophilic conditions). Composting seems to reduce or eliminate most of antibiotics residues, enteric bacteria, ARB and different representative ARG in manure more rapidly and effectively than lagoon storage. Our review highlights that despite the body of research accumulated in the last years, there are still important knowledge gaps regarding the contribution of manure to the AMR emergence, accumulation, spread and risk of human exposure in countries with high clinical resistance rates. Land microbiome before and after manure application, efficiency of different manure treatment techniques in decreasing the AMR levels in the natural environments and along the food chain must be investigated in depth, covering different geographical regions and countries and using harmonized methodologies. The support of stakeholders is required for the development of specific best practices for prudent – cautious use of antibiotics on farm animals. The use of human reserve antibiotics in veterinary medicine and of unprescribed animal antimicrobials should be stopped and the use of antibiotics on farms must be limited. This integrated approach is needed to determine the optimal conditions for the removal of antibiotic residues, ARB and ARG, to formulate specific recommendations for livestock manure treatment, storage and handling procedures and to translate them into practical on-farm management decisions, to ultimately prevent exposure of human population.

Adsorption-desorption and degradation of colistin in soils under aerobic conditions

Colistin has broad-spectrum activity against Gram-negative bacteria and has been considered as the last-resort treatment for multiantibiotic-resistant Gram-negative bacteria infections in human. And it is also world widely utilized as a veterinary medicine for the promotion of growth, prevention and control of diseases in livestock and poultry. Extensive use of colistin in husbandry results in the introduction of large amounts of colistin to the surrounding environment via animals' urine and feces, potentially inducing the prevalence of colistin resistance bacteria and the impact of the ecological environment. The study investigated the adsorption, desorption and degradation of colistin in soils using high sensitivity UPLC-MS/MS assays. An MS based assay was established to directly determine colistin in the soil. It was observed that the moderate adsorption affinity of colistin to the three soils with adsorption strength (1/n) ranging from 0.6897 to 1.3333. Colistin exhibited the highest adsorption affinity to the sandy loam, followed by the sand and loam. Despite of different characteristics of three soils, the adsorption capacity of the three soils was comparable. The adsorption of colistin to the three types of soils analyzed was irreversible. The degradation experiments showed that the degradation of colistin in the sandy loam was relatively slow with a degradation half-life in a range of 13.2-29.7 days when colistin was applied to the sandy loam at a level of 10 ~ 40 µg/g. The degradation of colistin occurred in the mixture of the sandy loam and feces recovered from the colistin treated broiler as well. 25% of colistin remained in the mixture under environmental conditions after 14 days. Composting the sandy loam by directly covering the soil surface with colistin treated broilers' feces resulted in the introduction of colistin to the sandy loam. Colistin was observed in both the topsoil from the contact surface and sandy loam samples collected 20 cm below the contact surface. The understanding of adsorption-desorption behaviors, degradation and mobility of colistin in soils might offer insights into the potential impact of colistin on the emergence and prevalence of resistant bacteria and the ecological environment.

Using highly stabilized digestate and digestate-derived ammonium sulphate to replace synthetic fertilizers: The effects on soil, environment, and crop production

Recovered fertilizers (a highly stabilized digestate and ammonium sulphate) obtained from anaerobic digestion of sewage sludge, were used on plot trials with a maize crop, in a comparison with synthetic fertilizers. After three consecutive cropping seasons, the soils fertilized with the recovered fertilizers (RF), compared to those fertilized with synthetic fertilizers (SF), did not show significant differences either in their chemical characteristics or in the accumulation of inorganic and organic pollutants (POPs). The RF ensured an ammonia N availability in the soil equal to that of the soil fertilized with SF, during the whole period of the experiment. Furthermore, no risks of N leaching were detected, and the use of RF did not result in a greater emission of ammonia or greenhouse gases than the use of SF. The agronomic results obtained using RF were equivalent to those obtained with SF (fertilizer use efficiency of 85.3 ± 10 and 93.6 ± 4.4% for RF and SF respectively). The data show that utilising a very stable digestate can be a good strategy to produce a bio-based fertilizer with similar performance to that of a synthetic fertilizer, without environmental risks.

Green synthesis of manganese-cobalt-tungsten composite oxides for degradation of doxycycline via efficient activation of peroxymonosulfate

The advanced oxidation process of peroxymonosulfate activated by solid catalyst is one of the main technologies to solve the pollution of antibiotics in water environment.In this work, a series of composites (MCW) containing Mn, Co, and W were synthesized using green ball milling, which does not produce the three wastes (waste gas, waste water and industrial residue). It shows a unique and high catalytic activity for peroxymonosulfate-based degradation of doxycycline (DC) under the pH condition between 4 and 9, and it can be reused five times. MCW composites remove DC using singlet oxygen and superoxide free radicals, as well as a large number of oxygen vacancies for electron storage. The formation rate of free radicals is determined by the conversion rates of Mn³⁺/Mn²⁺ and Co³⁺/Co²⁺. In addition, there are three ways to degrade DC to form 18 kinds of intermediates, and the toxicity of all the intermediates were predicted by ECOSAR program. The highly active catalysts obtained using a green synthetic route for the activation of peroxymonosulfate show a great potential for decontamination of antibiotics wastewater.

From gut to mud: dissemination of antimicrobial resistance between animal and agricultural niches

With increasing reports on antimicrobial resistance (AMR) in humans, animals and the environment, we are at risk of returning to a pre-antibiotic era. Therefore, AMR is recognized as one of the major global health threats of this century. Antibiotics are used extensively in farming systems to treat and prevent infections in food animals or to increase their growth. Besides the risk of a transfer of AMR between the human and the animal sector, there is another yet largely overlooked sector in the One Health triad. Human-dominated ecosystems such as agricultural soils are a major sink for antibiotics and AMR originating from livestock farming. This review summarizes current knowledge on the prevalence of AMR at the interface of animal and agricultural production and discusses the potential implications for human health. Soil resistomes are augmented by the application of manure from treated livestock. Subsequent transfer of AMR into plant microbiomes may likely play a critical role in human exposure to antibiotic resistance in the environment. Based on the knowledge that is currently available we advocate that more attention should be paid to the role of environmental resistomes in the AMR crisis.

Determination of veterinary drugs in microalgae biomass from photobioreactors fed with piggery wastewater

Concentration data of veterinary drugs in microalgae biomass collected from photobioreactors fed with piggery wastewaters are presented for the first time in this work. To this aim, a QuEChERS methodology and an ultrasound-assisted solid-liquid extraction have been assessed as sample preparation procedures with the purpose of determining 20 veterinary drugs, mainly antibiotics of different physico-chemical properties in addition to dexamethasone, fenbendazole and progesterone. Some critical operation parameters of the QuEChERS procedure were optimized by an experimental design but tetracycline, oxytetracycline, doxycycline, marbofloxacin and ciprofloxacin were not detected by the QuEChERS sample preparation. The use of a longer and thorough approach, a solid-liquid extraction with water/methanol in presence of primary secondary amine as a clean-up agent followed by solid-phase extraction on Oasis HLB cartridges, is recommended to monitor all intended analytes. The determination in extracts is carried out by ultra-high performance liquid chromatography-tandem mass spectrometry in selected reaction monitoring mode. Limits of detection about 0.2-42 ng per g of lyophilized microalgae sample, and repeatabilities about 6-46% (n = 5, RSDs) are reached. The solid-liquid extraction method was applied to microalgae biomass samples collected from a photobioreactor. Nine drugs were detected in the samples at relatively low concentration and a proportional relationship between the found concentrations and the octanol/water partition coefficients of the drugs has been outlined. Moreover, a linear ratio between the concentrations measured in biomass and effluent has been observed for most of the drugs.

Determination of colistin in luminal and parietal intestinal matrices of chicken by ultra-high-performance liquid chromatography-tandem mass spectrometry

Justification for continued use of colistin in veterinary medicine, for example medicated water, relies on pharmacokinetic/pharmacodynamic (PK/PD) studies that require accurate measurement of colistin content in the digestive tract. A method for the detection and quantification of colistin in poultry intestinal material was developed and validated. Colistin is not absorbed after oral administration, and the biophase is the gastrointestinal tract. Extraction of colistin from the matrix was achieved using solid‐phase extraction with a methanol:water (1:2; v/v) solution. Polymyxin B was used as an internal standard. Colistin A and colistin B, the main components of colistin, were separated, detected and measured using ultra‐high‐performance liquid chromatography coupled with tandem mass spectrometry (UHPLC‐MS/MS). The method was validated for linearity/quadraticity between 1.1 (LOQ) and 56.7 mg/kg. Mean accuracy was between 82.7% and 107.7% with inter‐ and intra‐day precision lower than 13.3% and 15% respectively. Freeze–thaw, long‐term and bench storage were validated. Incurred samples following colistin treatment in poultry at the approved clinical dose of 75,000 IU/kg in drinking water and oral gavage were quantifiable and in line with expected intestinal transit times. The method is considered appropriately accurate and precise for the purposes of pharmacokinetic analysis in the gastrointestinal tract.

A strategy to determine the fate of active chemical compounds in soil; applied to antimicrobially active substances

Data on the fate of chemical substances in the environment after e.g. manure application is mandatory input for risk assessment in perspective of a more circular biobased economy. Such fate studies include a persistence study to determine a half-life value and a mobility study. It is recognized that not only the native substance should be considered, but that also degradation products should be included that might exert a similar effect as the native substance. We report a tiered fate study strategy that starts with a persistence study. For non-persistent substances a study is performed to determine if degradation products have a similar effect as the native compound. If so, a procedure using high resolution mass spectrometry is suggested to identify the potentially active degradation products. Based on the outcomes, substances are divided into three categories: (I) persistent, (II) degradable to inactive products or (III) degradable to active products. Even though the priority is with category I and III, for all substances and possible degradation products a mobility study is proposed. The fate strategy is successfully applied to ten antimicrobially active substances originating from the tetracyclines, sulfonamides, diaminopyrimidines, fluoroquinolones, macrolides and lincosamides. The fluoroquinolones, tetracyclines and trimethoprim were relatively persistent. The sulfonamides, macrolides and lincomycin (the latter also depending on soil type) degraded relatively quickly. Tylosin A proved to degrade to antimicrobially active degradation products which were tentitatively identified as tylosin C, tylosin A acid, tylosin B acid and tylosin C acid.

Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Methods for the Quantification of Cefquinome, Ceftiofur, and Desfuroylceftiofuracetamide in Porcine Feces with Emphasis on Analyte Stability

Cefquinome and ceftiofur are β-lactam antibiotics used for the treatment of bacterial infections in swine. Although these antimicrobials are administered intramuscularly, the exposure of the gut microbiota to these cephalosporins is not well described. This exposure can contribute to the emergence and spread of antimicrobials in the environment and to the possible spread of antimicrobial resistance genes. To assess the impact of drug administration on the intestinal excretion of these antimicrobials it is essential to measure the amounts of native compound and metabolites in feces. Two (ultra)-high-performance liquid chromatography-tandem mass spectrometry ((U)HPLC–MS/MS) methods were developed and validated, one for the determination of cefquinome and ceftiofur and the other for the determination of ceftiofur residues, measured as desfuroylceftiofuracetamide, in porcine feces. The matrix-based calibration curve was linear from 5 ng g⁻¹ to 1000 ng g⁻¹ for cefquinome (correlation coefficient (r) = 0.9990 ± 0.0007; goodness of fit (gof) = 3.70 ± 1.43) and ceftiofur (r = 0.9979 ± 0.0009; gof = 5.51 ± 1.14) and quadratic from 30 ng g⁻¹ to 2000 ng g⁻¹ for desfuroylceftiofuracetamide (r = 0.9960 ± 0.0020; gof = 7.31 ± 1.76). The within-day and between-day precision and accuracy fell within the specified ranges. Since β-lactam antibiotics are known to be unstable in feces, additional experiments were conducted to adjust the sampling protocol in order to minimize the impact of the matrix constituents on the stability of the analytes. Immediately after sampling, 500 µL of an 8 µg mL⁻¹ tazobactam solution in water was added to 0.5 g feces, to reduce the degradation in matrix.

A portable fluorescent microsphere-based lateral flow immunosensor for the simultaneous detection of colistin and bacitracin in milk

The polypeptide antibiotics colistin (COL) and bacitracin (Baci) are extensively used as veterinary drugs and feedstock additives in the livestock industry, which inevitably causes residues in animal-origin food, which can accelerate human tolerance to antibiotics. In this study, a portable lateral flow immunoassay (LFIA) for the simultaneous determination of COL and Baci residues in milk was developed. The replacement of gold nanoparticles used in the traditional LFIA with fluorescent microspheres (FMs) to label monoclonal antibodies (mAbs) allowed qualitative and quantitative analyses within a few minutes. Based on the principle of competitive binding to FM-labelled mAbs between analytes in samples and fixed antigens on the membrane, the assay provided qualitative cut-off values of 100 and 50 ng mL-1 for Baci and COL in milk samples. Furthermore, a strip reader-based semi-quantitative detection system could detect lower limits of 7.85 and 1.89 ng mL-1 for Baci and COL, respectively. In conclusion, the proposed multiplex LFIA immunosensor provides an auxiliary analytical tool for the rapid and simultaneous screening of COL and Baci in large cohorts of samples.

Thermophilic anaerobic digestion as suitable bioprocess producing organic and chemical renewable fertilizers: A full-scale approach

This work reports a full-scale study in which organic wastes were transformed by high-solid thermophilic anaerobic digestion (HSAD), into N fertilizers and organic fertilizers, i.e. digestate. The produced fertilizers were characterized over 42 months and their properties were discussed in comparisons with literature data. HSAD coupled with N stripping technology led to ammonia sulphate production having high N concentration (74 ± 2 g kg^-1 wet weight), neutral pH (6.8 ± 1.3) and low traces of other elements. Digestate showed both higher carbon (C) content (314 ± 30 g kg^-1 on dry matter (DM) and biological stability than green composts, indicating good amendment properties. Digestate was also interesting for its N (77 ± 3.7 g kg^-1 dry matter - DM) content, half of it in the ammonia form, and P content (28 ± 4.1 g kg^-1 DM) that was 43% readily available as soluble P-orthophosphate. K content was low (6.5 ± 1.3 g kg^-1 DM), indicating poor fertilizing ability of digestate for this element. All organic pollutants investigated were much lower than the limits required for agricultural use and levels of some of them were lower than the content revealed for other organic matrices such as agricultural and energy crop digestates and compost. Emerging pollutants (i.e., pharmaceuticals) were tested as markers and they were found to be below the detection limit (<0.01 mg kg^-1 DM) indicating very low content. The results obtained showed that HSAD coupled with N stripping allowed transforming sewage sludge into fertilizers and soil improvers exploitable in agriculture.

Advances in Gold Nanoparticles-Based Colorimetric Aptasensors for the Detection of Antibiotics: An Overview of the Past Decade

Misuse of antibiotics has recently been considered a global issue because of its harmful effects on human health. Since conventional methods have numerous limitations, it is necessary to develop fast, simple, sensitive, and reproducible methods for the detection of antibiotics. Among numerous recently developed methods, aptasensors are fascinating because of their good specificity, sensitivity and selectivity. These kinds of biosensors combining aptamer with colorimetric applications of gold nanoparticles to recognize small molecules are becoming more popular owing to their advantageous features, for example, low cost, ease of use, on-site analysis ability using naked eye and no prerequisite for modern equipment. In this review, we have highlighted the recent advances and working principle of gold nanoparticles based colorimetric aptasensors as promising methods for antibiotics detection in different food and environmental samples (2011–2020). Furthermore, possible advantages and disadvantages have also been summarized for these methods. Finally, the recent challenges, outlook, and promising future perspectives for developing novel aptasensors are also considered.

Trace Analysis of Multiclass Antibiotics in Food Products by Liquid Chromatography-Tandem Mass Spectrometry: Method Development

It is commonly known that the widespread use of antibiotics has led to their existence in food products as residues and ingestion of these food products may create a selection pressure on bacteria inhabiting the human body. In this study, an optimized method for the analysis of antibiotic residues in different food groups, including cereals, meat, eggs, milk, vegetables, and fruits, was developed using solvent extraction, solid-phase extraction cleanup, and liquid chromatography-mass spectrometry (LC-MS/MS). The limits of detection (LODs) were achieved as 0.007-1.1, 0.008-0.46, 0.002-0.67, 0.007-0.63, 0.001-0.098, and 0.005-0.26 ng/g in ng/g in cereals, meat, eggs, milk, vegetables, and fruits, respectively. The overall average recoveries at three spiking levels of the 81 antibiotics (5, 25, and 50 ng/g dry weight) were 82 ± 26, 77 ± 26, 70 ± 34, 69 ± 31, 73 ± 29, and 62 ± 37% in cereals, meat, eggs, milk, vegetables, and fruits, respectively. The method was then applied to the analysis of the targets in the collected wheat flour, mutton, chicken egg, boxed milk, cabbage, and banana samples, with the total concentration of the antibiotics detected being 4.4, 2.3, 36, 5.5, 2.7, and 14 ng/g, respectively. This work suggests that the developed method provides a time- and cost-effective method to identify and quantify antibiotic residues in common food products.

Presence of veterinary antibiotics in livestock manure in two Southeastern Europe countries, Albania and Kosovo

Nowadays, veterinary drug application has become an integral practice in livestock farming. Veterinary antibiotics (VAs) are administered onto animals for therapeutic use; meanwhile, in some countries, they are used for growth promotion. To indicate the level of VAs use in livestock breeding in two countries, Albania and Kosovo, their presence was studied in the animal manure. In total, 38 manure samples, 22 from Kosovo and 16 samples from Albania, belonging to cattle, pig, and poultry, were collected and investigated for the presence of VAs. Seven VAs and 2 metabolites, from the groups of sulfonamides and tetracyclines, were identified by ultra-high pressure liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The detected antibiotics were sulfadiazine (SDZ), sulfathiazole (STZ), sulfamethazine (SMZ), oxytetracycline (OTC), tetracycline (TC), chlortetracycline (TC), and doxycycline (DOY). VAs were detected in 27% and 31.2% of the manure samples, from Kosovo and Albania, respectively, and the levels ranged from 0.04 to 10.1 mg kg^-1. VAs were widely detected (100%) in poultry manure from Kosovo, as well as poultry manure from Albania. The contamination rate ranged from pig manure (25%) to cow manure (66.6%). Sulfonamides were the most commonly detected VAs with maximum concentration of sulfadiazine (10.1 mg kg^-1) in poultry manure. Tetracyclines were most widely detected in poultry manure, as well as other animal manures. When it comes to the comparison between the two countries, VAs residues are more frequent per analyzed sample and higher in concentrations in the manure samples from Albania. Therefore, an environmental impact of VAs on both countries may be expected. These results indicate that VAs may enter the local ecosystem through manure application to agriculture and potentially may bring ecological risks.

A Calibration Curve Implanted Enzyme-Linked Immunosorbent Assay for Simultaneously Quantitative Determination of Multiplex Mycotoxins in Cereal Samples, Soybean and Peanut

In this study, a rapid and sensitive immunoassay method has been established based on calibration curve implanted enzyme-linked immunosorbent assay (C-ELISA) for the simultaneously quantitative determination of aflatoxin B1, deoxynivalenol and zearalenone in cereal samples, soybean and peanut. The C-ELISA avoids using the standard substances during the detection. The principle of the C-ELISA is to implant the optimized standard curve data into the matched analysis software which can make data processing more convenient and faster. The implanted calibration curve software was programmed with C plus plus. In the new immunoassay system for aflatoxin B1, deoxynivalenol and zearalenone, their linear detection ranges were from 0.03~0.81, 1.00~27.00 and 5.00~135.00 ng/g, respectively. Recovery rates from spiked samples ranged from 85% to 110% with the intra-assay coefficients of variation under 5%. Compared with HPLC method, the new method showed consistence in all the observed contents of the three mycotoxins in real samples. The new method can rapidly and reliably high throughput simultaneously screen for multiplex mycotoxins.

Genotoxic impact of emerging contaminant amoxicillin residue on zebra fish (Danio rerio) embryos

The widest-spectrum, most-consumed β-lactam antibiotic amoxicillin (AMX) is used to treat bovine mastitis that is caused primarily by many bacteria. Excessive use of antibiotics can lead to established residual contamination of the milk even after pasteurization. The amount of antibiotic residue above Maximum Residue Limit (MRL) has a negative impact on both public health and the environment. Therefore, the objective of this study is to determine the concentration of amoxicillin residue (AMXR) in raw and pasteurized milk samples of cow suffered from mastitis, by the standard methods of HPLC compared to pure AMX drug and effect of the said residue on the developmental toxicity and genotoxicity of zebra fish at 72 hpf and 48 hpf embryo, respectively. Results obtained by HPLC showed that AMXR exhibits 574.89 and 250.75 times higher concentration in the raw and pasteurized milk than MRL in compare to pure AMX drug. This current study showed that AMXR decreased the body length and yolk sac region, while the pure AMX drug-treated group showed increased height and length of the yolk sac and shorter body length relative to the other groups. The Comet Assay measured the DNA damage caused by AMXR. The group where AMXR were applied showed the highest percentage of tail DNA and tail moment relative to other groups. So, here AMXR is considered as the genotoxic contaminant that is emerging and affect on public health.

Understanding of Colistin Usage in Food Animals and Available Detection Techniques: A Review

Progress in the medical profession is determined by the achievements and effectiveness of new antibiotics in the treatment of microbial infections. However, the development of multiple-drug resistance in numerous bacteria, especially Gram-negative bacteria, has limited the treatment options. Due to this resistance, the resurgence of cyclic polypeptide drugs like colistin remains the only option. The drug, colistin, is a well-known growth inhibitor of Gram-negative bacteria like Acinetobacter baumanni, Enterobacter cloacae, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Technological advancements have uncovered the role of the mcr-1(mobilized colistin resistance) gene, which is responsible for the development of resistance in Gram-negative bacteria, which make them distinct from other bacteria without this gene. Additionally, food animals have been determined to be the reservoir for colistin resistance microbes, from which they spread to other hosts. Due to the adverse effects of colistin, many developed countries have prohibited its usage in animal foods, but developing countries are still using colistin in animal food production, thereby imposing a major risk to the public health. Therefore, there is a need for implementation of sustainable measures in livestock farms to prevent microbial infection. This review highlights the negative effects (increased resistance) of colistin consumption and emphasizes the different approaches used for detecting colistin in animal-based foods as well as the challenges associated with its detection.

Occurrence of Antibiotics in Influent and Effluent from 3 Major Wastewater-Treatment Plants in Finland

Wastewater-treatment plants (WWTPs) are regarded as one of the main sources of antibiotics in the environment. In the present study, the concentrations of multiple antibiotics and their metabolites belonging to 5 antibiotic classes were determined in 3 major Finnish WWTPs. An online solid phase extraction-liquid chromatography-tandem mass spectrometry method was used for the extraction and analysis of the compounds. The method was fully validated using real and synthetic wastewaters. Seven antibiotics and 3 metabolites were found in the analyzed samples. Sulfonamides were removed most efficiently, whereas macrolides usually showed negative removal efficiency during the treatment, which means that the concentrations for individual antibiotics determined in the effluent samples were higher than in the influent samples. Sulfadiazine was found at concentrations up to 1018 ng/L, which was the highest concentration of any of the detected antibiotics in influent. In the effluent samples, the highest mean concentration was found for trimethoprim (532 ng/L). The measured mass loads of the antibiotics and metabolites to the receiving waters ranged from 2 to 157 mg/d per 1000 population equivalent. The evaluated environmental risk assessment showed that clarithromycin and erythromycin might pose a risk to the environment. The present study further underlines the importance of implementing technology for efficient removal of xenobiotics during wastewater treatment. Environ Toxicol Chem 2020;39:1774-1789. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A review: Recent advances in ultrasensitive and highly specific recognition aptasensors with various detection strategies

One of the most studied topics in analytical chemistry and physics is to develop bio-sensors. Aptamers are small single-stranded RNA or DNA oligonucleotides (5-25 kDa), which have advantages in comparison to their antibodies such as physicochemical stability and high binding specificity. They are able to integrate with proteins or small molecules, including intact viral particles, plant lectins, gene-regulation factor, growth factors, antibodies and enzymes. The aptamers have reportedly shown some unique characteristics, including long shelf-life, simple modification to provide covalent bonds to material surfaces, minor batch variation, cost-effectiveness and slight denaturation susceptibility. These features led important efforts toward the development of aptamer-based sensors, known as apta-sensors classified into optical, electrical and mass-sensitive based on the signal transduction mode. This review provided a number of current advancements in selecting, development criteria, and aptamers application with the focus on the effect of apta-sensors, specifically for disease-associated analyses. The review concentrated on the current reports of apta-sensors that are used for evaluating different food and environmental pollutants.

Removal of veterinary antibiotics from swine wastewater using anaerobic and aerobic biodegradation

High amounts of antibiotics, used in animal farms for the prevention of diseases, are released back into the natural environment with a possible risk of chronic toxicity to other organisms and the development of antibiotic-resistant genes. The antibiotics, including sulfonamides and β-lactams, detected in swine wastewater were between 99.2 and 339.3 μg/L. The typical on-site swine wastewater treatment process turned out to be inadequate, reflected by the high conventional contaminant and antibiotic residuals even under a long hydraulic residence time (HRT, around 2-3 months). The lab-scale combined anaerobic and aerobic biological process showed that anaerobic digestion was mainly responsible for chemical oxygen demand (COD) reduction and aerobic biodegradation contributed significantly to antibiotic removal, with overall removal efficiencies of 95% for COD and 92% for antibiotics under a short HRT of 3.3 days. The removal of selected antibiotics could be a combined result of biodegradation, the balance between adsorption and desorption, and the transformation between antibiotic metabolites and their parent antibiotics. The current work provides valuable insights into the appropriate selection and optimisation of biological processes for the treatment of typical wastewater with high COD and trace antibiotics.

A review of the occurrence of selected micropollutants and microorganisms in different raw and treated manure - Environmental risk due to antibiotics after application to soil

This study consists of a review based on 104 papers published between 1980 and 2019, which dealt with the occurrence of pharmaceuticals, hormones and a selection of microorganisms in raw and treated manure from different types of animal farms. The selected pharmaceuticals and hormones are those regularly administered to livestock for treating and preventing diseases. Worldwide, manure is commonly spread on soil as a fertilizer due to its nutrient content. However, this practice also represents a potential pathway for micropollutant release into the environment. In this context, this study evaluates the predicted concentrations of some antibiotics in soil after the application of swine slurry on soil and compares them with corresponding measured concentrations found in the literature. Enrofloxacin, oxytetracycline and chlortetracycline were the antibiotics with the highest concentrations that were found in raw and treated manure and that showed a high risk together with sulfamethazine. Future research should focus on monitoring other pathogens, parent compounds and their main metabolites in raw and treated manure, studying the spread and development of antibiotic resistance genes in the environment due to residues of antibiotics in manure applied to soil, and evaluating predicted no effect concentrations of pharmaceuticals and hormones commonly administered to livestock with regard to terrestrial organisms.

Antibiotic Residues and Antibiotic-Resistant Bacteria in Pig Slurry used to Fertilize Agricultural Fields

Pig manure may contain antibiotic residues, antibiotic-resistant bacteria or pathogens, which may reach the environment upon fertilization. During this study, 69 antibiotic residues belonging to 12 classes were quantified in 89 pig slurry samples. These samples were also studied for the presence of Salmonella and for E. coli resistant to meropenem, colistin, ciprofloxacin, or cefotaxim. The obtained isolates were further tested for antibacterial susceptibility. No antibiotic residues were detected in four samples, whereas in the other samples, up to 12 antibiotics were found. The most frequently detected antibiotic residues were doxycycline, sulfadiazine, and lincomycin. Doxycycline was found in the highest concentration with a mean of 1476 µg/kg manure (range: 18-13632 µg/kg). Tylosin and oxytetracycline were found with mean concentrations of 784 µg/kg (range: 17-5599 µg/kg) and 482 µg/kg (range: 11-3865 µg/kg), respectively. Lincomycin, had a mean concentration of 177 µg/kg manure (range: 9-3154 µg/kg). All other 18 antibiotic residues were found with mean concentrations of less than 100 µg/kg manure. Fifty-one slurry samples harbored Salmonella; 35% of the Salmonella isolates were sensitive to a panel of 14 antibiotics, whereas the other 65% were resistant up to five antibiotics. For E. coli, 52 manure samples contained E. coli isolates which were resistant to ciprofloxacin and 22 resistant to cefotaxime. All ciprofloxacin and cefotaxime-resistant isolates were multi-resistant, with resistance up to nine and eight antibiotics, respectively. This research indicates that pig slurry used for fertilization often contains antibiotic residues and antibiotic-resistant bacteria, including pathogens.

Presence and fate of antibiotic residues, antibiotic resistance genes and zoonotic bacteria during biological swine manure treatment

The presence and dissemination of antibiotic residues, antibiotic resistance genes and zoonotic bacteria in the environment is of growing concern worldwide. Manure management practices, such as biological removal of nitrogen from swine manure, may help to decrease levels of antibiotic residues, antibiotic resistance genes and zoonotic bacteria present in manure before fertilization, thereby reducing environmental contamination. Therefore, the aim of this study was to monitor the presence and fate of seven antibiotic residues (colistin, sulfadiazine, trimethoprim, doxycycline, oxytetracycline, ceftiofur and tylosin A), nine antibiotic resistance genes (tet(B), tet(L), tet(M), tet(O), tet(Q), tet(W), erm(B), erm(F) and sul2) and two zoonotic bacteria (Salmonella Typhimurium and Campylobacter coli) during biological nitrogen removal from swine manure over time. Samples from the raw manure, the solid fraction, the liquid fraction and the storage lagoon were analyzed on two farms at six time points with an interval of two weeks. Only the antibiotics which were used during the three months preceding the first sampling could be detected before and after biological nitrogen removal from swine manure. Of all the antibiotics studied, doxycycline was recovered in all of the samples and sulfadiazine was recovered in most samples on both farms. For both antibiotics, there appears to be a reduction of the amount of residues present in the storage lagoon compared to the liquid fraction, however, this reduction was not statistically significant. A significant reduction of the relative abundances of most of the antibiotic resistance genes studied was observed when comparing the liquid fraction and the storage lagoon. For tet(L), no differences were observed between the fractions sampled and for sul2 and erm(F), a significant increase in relative abundances was observed on the second farm sampled. For the zoonotic bacteria, a reduction of at least 1 log was observed after biological nitrogen removal from swine manure. The results indicate that the concentration of certain antibiotic residues and several antibiotic resistance genes and the amount of zoonotic bacteria present in the manure may be reduced in the end product of the biological nitrogen removal from swine manure.

Antibiotic residues in milk: Past, present, and future

Now-a-days, various types of antibiotics are being used worldwide in veterinary sector indiscriminately for promotion of growth and treatment of the livestock. Significant portions of antibiotics are released through milk of dairy animals unaltered and exert serious harmful effects on human health. This review evaluates and compare researches on antibiotic residues in milk in published literatures from Pubmed, CrossRef, CAB direct, DOAJ, JournalTOCs, AGRICOLA, ScientificGate, Electronic Journals Library, CAB abstracts, Global Health Databases, Global Impact Factor, Google Scholar, Park Directory of Open Access Journals, BanglaJOL and ISC E-Journals. Antibiotics residue in milk was first detected in 60s and then with an increasing trend with highest after 2,000 (188). The highest no. of works, 49 (21.87%) were accomplished in China, followed by Spain, 30 (13.39%); Germany, 11 (4.91%); and USA, 10 (4.46%). Continent-wise highest researches are published from Europe, 105 (46.88%), followed by Asia, 77 (34.38%); South America, 18 (8.04%); North America, 16 (7.14%); and Africa, 8 (3.57%). For detection, Bovine milk sample is mostly used, 193 (86.16%), followed by ovine, 19 (8.48%); and caprine, 14 (6.25%). Acetonitrile was used in maximum cases (77) for processing the samples. Chromatographic technique was the highest, 115 (51.34%) for detection. Residue of β-lactam group have been detected mostly 133 (36.54%), followed by tetracyclines, 51 (14.01%); fluoroquinolones, 49 (13.46%); sulfonamides, 46 (12.64%); and aminoglycosides, 38 (10.44%). This review observe that antibiotics residues are more common in milk samples that are being manifested in increasing researches on antibiotic detection and measures should adopt to cease this residue.

Rapid determination of antioxidant molecules in volatiles of rose tea by gas chromatography-mass spectrometry combined with DPPH reaction

Volatiles have been regarded as active substances in many foods, whose chemicals can be analyzed by GC-MS qualitatively and quantitatively. However, the activities of volatiles are often studied as a whole, and it has no an effective method to determine that which molecule is active in volatiles by far. In order to identify the antioxidant molecules in volatiles, a rapid determination method was developed by GC-FID/MS combined with DPPH radical reaction in this study. Three antioxidant molecules were identified and validated among 20 components in rose tea infusion. Their activity validation and the methodological evaluation indicated this method could be used for distinguishing antioxidant molecules in volatiles rapidly and effectively.

A new extraction procedure to abate the burden of non-extractable antibiotic residues in manure

Through agricultural soil fertilization using organic manure, antibiotic residues can accumulate in the environment. In order to assess the risks of environmental pollution by veterinary drugs, monitoring of manure for antibiotic residues is necessary. As manure is a complex matrix, extraction of antibiotics proved to be challenging. In this study, 24 extraction solvents were assessed for the extraction of residues from manure representing ten antibiotics from the antibiotic classes tetracyclines, quinolones, macrolides, lincosamides and sulfonamides. Especially for the tetracyclines and quinolones the extraction solvent selection is critical, due to high fractions of non-extractable residues especially when using aqueous solvents (62-77% and 90-95% respectively when using milli-Q water). In contrast, sulfonamides can effectively be extracted with aqueous solvents. Overall, 0.125% trifluoroacetic acid in acetonitrile in combination with McIlvain-EDTA buffer proved to be the most effective extraction solvent. A longitudinal study pointed out that most antibiotics bind to solid manure particles instantaneously after addition. Trimethoprim is an exception, but because by using the optimal extraction solvent, the optimum fraction of bound residues is desorbed, this does not hamper quantitative analysis when using spiked manure quality control samples. Based on these new insights, the current in-house multi-residue LC-MS/MS method for manure analysis, containing 48 antibiotics, was revised, additionally validated and applied to 34 incurred manure samples.

Manure and Doxycycline Affect the Bacterial Community and Its Resistome in Lettuce Rhizosphere and Bulk Soil

Manure application to agricultural soil introduces antibiotic residues and increases the abundance of antibiotic-resistant bacteria (ARB) carrying antibiotic resistance genes (ARGs), often located on mobile genetic elements (MGEs). The rhizosphere is regarded as a hotspot of microbial activity and gene transfer, which can alter and prolong the effects of organic fertilizers containing antibiotics. However, not much is known about the influence of plants on the effects of doxycycline applied to soil via manure. In this study, the effects of manure spiked with or without doxycycline on the prokaryotic community composition as well as on the relative abundance of ARGs and MGEs in lettuce rhizosphere and bulk soil were investigated by means of a polyphasic cultivation-independent approach. Samples were taken 42 days after manure application, and total community DNA was extracted. Besides a pronounced manure effect, doxycycline spiking caused an additional enrichment of ARGs and MGEs. High-throughput quantitative PCR revealed an increase in tetracycline, aminoglycoside, and macrolide-lincosamide-streptogramin B (MLSB) resistance genes associated with the application of manure spiked with doxycycline. This effect was unexpectedly lower in the rhizosphere than in bulk soil, suggesting a faster dissipation of the antibiotic and a more resilient prokaryotic community in the rhizosphere. Interestingly, the tetracycline resistance gene tetA(P) was highly enriched in manure-treated bulk soil and rhizosphere, with highest values observed in doxycycline-treated bulk soil, concurring with an enrichment of Clostridia. Thus, the gene tetA(P) might be a suitable marker of soil contamination by ARB, ARGs, and antibiotics of manure origin. These findings illustrate that the effects of manure and doxycycline on ARGs and MGEs differ between rhizosphere and bulk soil, which needs to be considered when assessing risks for human health connected to the spread of ARGs in the environment.

The persistence of a broad range of antibiotics during calve, pig and broiler manure storage

After administration to livestock, a large fraction of antibiotics are excreted unchanged via excreta and can be transferred to agricultural land. For effective risk assessment a critical factor is to determine which antibiotics can be expected in the different environmental compartments. After excretion, the first relevant compartment is manure storage. In the current study, the fate of a broad scope of antibiotics (n = 46) during manure storage of different livestock animals (calves, pigs, broilers) was investigated. Manure samples were fortified with antibiotics and incubated during 24 days. Analysis was carried out by LC-MS. The dissipation of the antibiotics was modelled based on the recommendations of FOCUS working group. Sulphonamides relatively quickly dissipate in all manure types, with a DT90 of in general between 0.2 and 30 days. Tetracyclines (DT90 up to 422 days), quinolones (DT90 100-5800 days), macrolides (DT90 18-1000 days), lincosamides (DT90 135-1400 days) and pleuromutilins (DT90 of 49-1100 days) are in general much more persistent, but rates depend on the manure type. Specifically lincomycin, pirlimycin, tiamulin and most quinolones are very persistent in manure with more than 10% of the native compound remaining after a year in most manure types. For all compounds tested in the sub-set, except the macrolides, the dissipation was an abiotic process. Based on the persistence and current frequency of use, oxytetracycline, doxycycline, flumequine and tilmicosin can be expected to end up in environmental compartments. Ecotoxicological data should be used to further prioritize these compounds.

Aptamer-Based Biosensors for Antibiotic Detection: A Review

Antibiotic resistance and, accordingly, their pollution because of uncontrolled usage has emerged as a serious problem in recent years. Hence, there is an increased demand to develop robust, easy, and sensitive methods for rapid evaluation of antibiotics and their residues. Among different analytical methods, the aptamer-based biosensors (aptasensors) have attracted considerable attention because of good selectivity, specificity, and sensitivity. This review gives an overview about recently-developed aptasensors for antibiotic detection. The use of various aptamer assays to determine different groups of antibiotics, like β-lactams, aminoglycosides, anthracyclines, chloramphenicol, (fluoro)quinolones, lincosamide, tetracyclines, and sulfonamides are presented in this paper.

Lack of experimental evidence to support mcr-1-positive Escherichia coli strain selection during oral administration of colistin at recommended and higher dose given by gavage in weaned piglets

In this study, we assessed the selective effect of colistin administered orally to healthy weaned piglets harbouring an intestinal mcr-1-positive Escherichia coli strain. Maximum recommended dose and a higher dose often used in European pig farms were given by gavage. No selection of the mcr-1-positive strain was observed in our controlled conditions, irrespective of the dose. Further investigations in real farming conditions seem necessary.