Metabolic study of enrofloxacin and metabolic profile modifications in broiler chicken tissues after drug administration

Pharmaceutical metabolite identification in lettuce (Lactuca sativa) and earthworms (Eisenia fetida) using liquid chromatography coupled to high-resolution mass spectrometry and in silico spectral library

Pharmaceuticals released into the aquatic and soil environments can be absorbed by plants and soil organisms, potentially leading to the formation of unknown metabolites that may negatively affect these organisms or contaminate the food chain. The aim of this study was to identify pharmaceutical metabolites through a triplet approach for metabolite structure prediction (software-based predictions, literature review, and known common metabolic pathways), followed by generating in silico mass spectral libraries and applying various mass spectrometry modes for untargeted LC-qTOF analysis. Therefore, Eisenia fetida and Lactuca sativa were exposed to a pharmaceutical mixture (atenolol, enrofloxacin, erythromycin, ketoprofen, sulfametoxazole, tetracycline) under hydroponic and soil conditions at environmentally relevant concentrations. Samples collected at different time points were extracted using QuEChERS and analyzed with LC-qTOF in data-dependent (DDA) and data-independent (DIA) acquisition modes, applying both positive and negative electrospray ionization. The triplet approach for metabolite structure prediction yielded a total of 3762 pharmaceutical metabolites, and an in silico mass spectral library was created based on these predicted metabolites. This approach resulted in the identification of 26 statistically significant metabolites (p < 0.05), with DDA + and DDA - outperforming DIA modes by successfully detecting 56/67 sample type:metabolite combinations. Lettuce roots had the highest metabolite count (26), followed by leaves (6) and earthworms (2). Despite the lower metabolite count, earthworms showed the highest peak intensities, closely followed by roots, with leaves displaying the lowest intensities. Common metabolic reactions observed included hydroxylation, decarboxylation, acetylation, and glucosidation, with ketoprofen-related metabolites being the most prevalent, totaling 12 distinct metabolites. In conclusion, we developed a high-throughput workflow combining open-source software with LC-HRMS for identifying unknown metabolites across various sample types.

Intra-species differences shape differences of enrofloxacin residues and its degradation products in tilapia: A precise risk assessment

The increasing use and abuse of antibiotics in agriculture and aquaculture necessitates a more thorough risk assessment. We first advocate a precise assessment that subdivides the assessment scope from interspecies to intraspecific levels. Differences in ENR residues and degradation within the intraspecific category were simultaneously explored. This study chose red and GIFT tilapia, both belonging to the intra-specific category of tilapia, for an enrofloxacin (ENR) exposure experiment. Red tilapia had a lower area under the curve (AUC) representing drug accumulation, indicating a notably shorter withdrawal period (7 days) compared to GIFT tilapia (31.4 days) in the edible parts. While four potential transformation pathways were proposed for ENR in tilapia, red tilapia had fewer detected degradation products (6 items) than GIFT tilapia (10 items), indicating a simpler transformation pathway in red tilapia. Predictive assessments using the Toxtree model revealed that of the four extra degradation products in GIFT tilapia, two may possess carcinogenic and mutagenic properties. Overall, differences were observed in ENR residues and degradation within the intraspecific category, with red tilapia presenting lower risks than GIFT tilapia. This work suggests a new strategy to perfect the methodology for antibiotic risk assessment and facilitate systematic antibiotic administration management in the future.

Fate of fluoroquinolones in field soil environment after incorporation of poultry litter from a farm with enrofloxacin administration via drinking water

The practice of incorporating animal manure into soil is supported within the European Circular economy as a possible substitute for mineral fertilizers and will become crucial for the sustainability of agriculture. However, this practice may indirectly contribute to the dissemination of antibiotics, resistance bacteria, and resistance genes. In this study, medicated drinking water and poultry litter samples were obtained from a broiler-chick farm. The obtained poultry litter was incorporated into the soil at the experimental field site. The objectives of this research project were first to develop analytical methods able to quantify fluoroquinolones (FQs) in medicated drinking water, poultry litter, and soil samples by LC-MS; second to study the fate of these FQs in the soil environment after incorporation of poultry litter from flock medicated by enrofloxacin (ENR); and third to screen the occurrence of selected fluoroquinolone resistance encoding genes in poultry litter and soil samples (PCR analysis). FQs were quantified in the broiler farm's medicated drinking water (41.0 ± 0.3 mg∙L-1 of ENR) and poultry litter (up to 70 mg∙kg-1 of FQs). The persistence of FQs in the soil environment over 112 days was monitored and evaluated (ENR concentrations ranged from 36 μg∙kg-1 to 9 μg∙kg-1 after 100 days). The presence of resistance genes was confirmed in both poultry litter and soil samples, in agreement with the risk assessment for the selection of AMR in soil based on ENR concentrations. This work provides a new, comprehensive perspective on the entry and long-term fate of antimicrobials in the terrestrial environment and their consequences after the incorporation of poultry litter into agricultural fields.

The enrofloxacin pollution control from fish to environment

Enrofloxacin (ENR) is used to prevent and treat fish diseases widely. However, its pollution is increasing public concern on human health and aquatic ecosystem safety. This review aims to find its pollution mechanisms and control way. It is found: (1) The excessive ENR administration is the main source, the sediment ENR escaping from photolysis is the secondary ENR pollution source; (2) The ENR-rich fishes were benthic lipid-rich fishes which can simultaneously absorb administration ENR and sediment ENR, the ENR bioaccumulation is positively related to the fish habitats ENR level and fish lipids content; (3) The ENR t1/2 varies with fish age, body weight, feedstuff lipids and crude fiber level, temperature, salinity, administration mode and dose; Consequently, the first control way is to conduct the minimum inhibitory concentration ENR, combining herbal medicines with antibacterial and detoxification functions. The second way is to develop the enrichment and removal techniques for sediment ENR.

Improved LC/MS/MS Quantification Using Dual Deuterated Isomers as the Surrogates: A Case Analysis of Enrofloxacin Residue in Aquatic Products

Extensive and high residue variations in enrofloxacin (ENR) exist in different aquatic products. A novel quantitative method for measuring ENR using high-performance liquid chromatography-tandem mass spectrometry was developed employing enrofloxacin-d₅ (ENR-d₅) and enrofloxacin-d₃ (ENR-d₃) as isotope surrogates. This reduced the deviation of detected values, which results from the overpass of the linear range and/or the large difference in the residue between the isotope standard and ENR, from the actual content. Furthermore, high residue levels of ENR can be directly diluted and re-calibrated by the corresponding curve with the addition of high levels of another internal surrogate without repeated sample preparation, avoiding the overflow of the instrument response. The validation results demonstrated that the method can simultaneously determine ENR residues from MQL (2 µg/kg) to 5000 × MQL (method quantification limit) with recoveries between 97.1 and 106%, and intra-precision of no more than 2.14%. This method realized a wide linear calibration range with dual deuterated isomers, which has not been previously reported in the literature. The developed method was successfully applied to the analysis of ENR in different aquatic products, with ENR residue levels varying from 108 to 4340 μg/kg and an interval of precision in the range of 0.175~6.72%. These results demonstrate that batch samples with a high variation in ENR residues (over the linear range with a single isotope standard) can be detected by the dual isotope surrogates method in a single sample preparation process.

Irrigation Ponds as Sources of Antimicrobial-Resistant Bacteria in Agricultural Areas with Intensive Use of Poultry Litter

Poultry litter is widely used worldwide as an organic fertilizer in agriculture. However, poultry litter may contain high concentrations of antibiotics and/or antimicrobial-resistant bacteria (ARB), which can be mobilized through soil erosion to water bodies, contributing to the spread of antimicrobial resistance genes (ARGs) in the environment. To better comprehend this kind of mobilization, the bacterial communities of four ponds used for irrigation in agricultural and poultry production areas were determined in two periods of the year: at the beginning (low volume of rainfall) and at the end of the rainy season (high volume of rainfall). 16S rRNA gene sequencing revealed not only significantly different bacterial community structures and compositions among the four ponds but also between the samplings. When the DNA obtained from the water samples was PCR amplified using primers for ARGs, those encoding integrases (intI1) and resistance to sulfonamides (sul1 and sul2) and β-lactams (blaGES, blaTEM and blaSHV) were detected in three ponds. Moreover, bacterial strains were isolated from CHROMagar plates supplemented with sulfamethoxazole, ceftriaxone or ciprofloxacin and identified as belonging to clinically important Enterobacteriaceae. The results presented here indicate a potential risk of spreading ARB through water resources in agricultural areas with extensive fertilization with poultry litter.

Determination of antimicrobial agents and their transformation products in an agricultural water-soil system modified with manure

Manure fertilization is the primary source of veterinary antimicrobials in the water-soil system. The research gap is the fate of antimicrobials after their release into the environment. This study aimed to provide a detailed and multi-faceted examination of fertilized cultivated fields using two types of manure (poultry and bovine) enriched with selected antimicrobials. The research focused on assessing the mobility and stability of antimicrobials in the water-soil system. Additionally, transformation products of antimicrobials in the environment were identified. The extraction (solid-phase extraction and/or solid-liquid extraction) and LC-MS/MS analysis procedures were developed to determine 14 antimicrobials in the soil and pore water samples. Ten out of fourteen antimicrobials were detected in manure-amended soil and pore water samples. The highest concentration in the soil was 109.1 ng g^-1 (doxycycline), while in pore water, it was 186.6 ng L^-1 (ciprofloxacin). Sixteen transformation products of antimicrobials were identified in the soil and soil-related pore water. The same transformation products were detected in both soil and soil pore water extracts, with significantly higher signal intensities observed in soil extracts than in water. Transformation products were formed in oxidation, carbonylation, and ring-opening reactions.

Metabolites in Milk after Enrofloxacin Treatment and Their Persistence to Temperature

In this work, metabolomic profile changes in milk from cows affected by mastitis and treated with enrofloxacin (ENR) have been studied using LC-HRMS techniques. Principal component analysis was applied to the obtained results, and the interest was focused on changes affecting compounds without a structural relationship to ENR. Most of the compounds, whose concentrations were modified as a result of the pharmacological treatment and/or the pathological status, were related to amino acids and peptides. Compounds that may become possible biomarkers for either disease or treatment have been detected. Additionally, the alterations caused by thermal processes, such as those applied to milk before consumption, on the identified metabolites have also been considered.

Uptake of Pharmaceutical Pollutants and Their Metabolites from Soil Fertilized with Manure to Parsley Tissues

Manure is a major source of soil and plant contamination with veterinary drugs residues. The aim of this study was to evaluate the uptake of 14 veterinary pharmaceuticals by parsley from soil fertilized with manure. Pharmaceutical content was determined in roots and leaves. Liquid chromatography coupled with tandem mass spectrometry was used for targeted analysis. Screening analysis was performed to identify transformation products in the parsley tissues. A solid-liquid extraction procedure was developed combined with solid-phase extraction, providing recoveries of 61.9–97.1% for leaves and 51.7–95.6% for roots. Four analytes were detected in parsley: enrofloxacin, tylosin, sulfamethoxazole, and doxycycline. Enrofloxacin was detected at the highest concentrations (13.4–26.3 ng g⁻¹). Doxycycline accumulated mainly in the roots, tylosin in the leaves, and sulfamethoxazole was found in both tissues. 14 transformation products were identified and their distribution were determined. This study provides important data on the uptake and transformation of pharmaceuticals in plant tissues.

Suspect screening of antimicrobial agents transformation products in environmental samples development of LC-QTrap method running in pseudo MRM transitions

The aim of the work was to develop a new HPLC-MS/MS method that allows for the simultaneous detection of antimicrobials agents (targeted analysis) and their transformation products (non-targeted analysis), which enabled the elucidation of their transformation pathways in the environment. Targeted analysis was performed for 16 selected antimicrobials agents (AMs) in wastewater collected at different stages of the treatment process and river water from sections before and after wastewater discharge. The samples were collected in the Łyna sewage treatment plant (Olsztyn, Poland) in three measuring periods at different seasons. Analytes were selected from tetracyclines, fluoroquinolones, β-lactams, macrolides, glycopeptides, lincosamides and synthetic antibiotics. As a part of the targeted analysis, 13 AMs were detected in wastewater samples, and 7 of them in river water samples. However, their presence and concentrations were closely related to the type of the sample and the season in which the sample was taken. The highest concentrations of AMs were detected in samples collected in September (max. 1643.7 ng L^-1 TRI), while the lowest AMs concentrations were found in samples collected in June (max. 136.1 ng L^-1 CLR). The total content of AMs in untreated wastewater was in the range of 1.42-1644 ng L^-1, while in the river water was for upstream 1.22-48.73 ng L^-1 and for downstream 2.24-149 ng L^-1. In the non-target analysis, 33 degradation products of the selected AMs were identified, and the transformation pathways of their degradation were speculated. In the course of the research, it was found that as a result of the processes taking place in wastewater treatment plant, the parent substances are transformed into a number of stable transformation products. Transformation products resulted from hydroxylation, ring opening, oxidation, methylation or demethylation, carboxylation, or cleavage of the CN bond of the parent AMs.

Comprehensive Metabolomics Analysis of Nontargeted LC-HRMS Data Provides Valuable Insights Regarding the Origin of Veterinary Drug Residues

Liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) complements standard triple-quadrupole mass spectrometry in veterinary drug residue control. LC-HRMS offers the opportunity for nontargeted screening for metabolites and biomarkers representing metabolic changes. In this work, the feasibility of a nontargeted metabolomics approach based on LC-HRMS data (LC-Q-Orbitrap and LC-Q-TOF) to distinguish between porcine muscle tissue from infected animals and from healthy animals is demonstrated. The differences arise from various compounds associated with metabolic changes in infected animals. Two new biomarker candidates have been identified: tripeptide prolyphenylalanylglycine and a lysophosphatidylcholine derivative. For the first time, a bivariate data analysis procedure is described that may be used to evaluate whether the presence of antibiotic residues points to a therapeutic application or may be the result of a contamination during sampling and/or analysis.

Bioaccumulation, Biotransformation, and Multicompartmental Toxicokinetic Model of Antibiotics in Sea Cucumber (Apostichopus japonicus)

Extensive application of antibiotics leads to their ubiquitous occurrence in coastal aquatic environments. However, it remains largely unknown whether antibiotics can be bioaccumulated and biotransformed in major mariculture organisms such as sea cucumbers and toxicokinetic models for Echinodermata are lacking. In this study, laboratory exposure experiments on juvenile sea cucumber (Apostichopus japonicus) were performed for seven antibiotics (sulfadiazine, sulfamethoxazole, trimethoprim, enrofloxacin, ofloxacin, clarithromycin, and azithromycin). Field sea cucumber and surrounding seawater samples were also analyzed. Results show that the sea cucumbers tend to accumulate high concentrations of the antibiotics with kinetic bioconcentration factors (BCFs) up to 1719.7 L·kg^-1 for ofloxacin. The BCFs determined in the laboratory agree well with those estimated from the field measurements. Seven biotransformation products (BTPs) of the antibiotics were identified, four of which were not reported previously in aquatic organisms. The BTPs were mainly found in the digestive tract, indicating its high capacity in the biotransformation. A multicompartmental toxicokinetic model based on the principles of passive diffusion was developed, which can successfully predict time-course concentrations of the antibiotics in different compartments of the juvenile sea cucumbers. The findings may offer a scientific basis for assessing health risks and guiding healthy mariculture of sea cucumbers.

Environmental Conversion Path Inference of New Designed Fluoroquinolones and Their Potential Environmental Risk

Fluoroquinolone (FQ) derivatives with environmental friendliness regarding photodegradation, bioconcentration, and genotoxicity were selected from our previous works so that their transformation pathways of biological metabolism, photodegradation, microbial degradation, and chlorination disinfection could be studied. The pathways of these molecules and their derivatives were simulated to investigate the genotoxicity of their transformation products. The results showed that the genotoxicity of the biological metabolites, photodegradation products, and microbial degradation products of the maternal FQ derivatives partially increased, whereas the disinfection by-products exhibited lower genotoxicity than their precursors. Some designed FQ molecular derivatives still had potential environmental risks in biological metabolism, photodegradation, and microbial degradation. This study demonstrated that it is necessary to take into account the potential environmental risks of the transformed products of the modified FQs molecules during biometabolism, photodegradation, microbial degradation, and chlorination processes when designing novel FQ molecules. In future studies, assessing the potential environmental risks during various artificial or natural processes can be applied to screen environmentally friendly novel FQ molecules to avoid and or reduce their threat to environmental and human health.

Uptake and depuration of eight fluoroquinolones (FQs) in common carp (Cyprinus carpio)

Fluoroquinolones (FQs) are extensively used in humans and animals, which have aroused wide attention due to the emergence of FQ resistant bacteria and frequent detection in water, sediment and organism. However, little information is available about the bioconcentration and tissue distribution of FQs in fish. In the present study, we investigated the uptake and depuration of eight FQs (balofloxacin (BAL), enoxacin (ENO), enrofloxacin (ENR), fleroxacin (FLE), lomefloxacin (LOM), moxifloxacin (MOX), ofloxacin (OFL), sparfloxacin (SPA)) in common carp under controlled laboratory conditions. The results showed that all target FQs could accumulate in fish tissues, and had a similar tendency over time during the whole uptake and depuration periods. The uptake rate constant (k₁), depuration rate constant (k₂) and half-lives (t_1/2) were in the ranges of 0.007-3.599 L/(kg·d), 0.051-0.283 d^-1 and 2.4-10.7 d, respectively. The ranges of bioconcentration factors (BCFs) were 0.24-39.55 L/kg, 0.21-24.97 L/kg and 0.04-1.07 L/kg in liver, kidney and muscle, respectively. BCFs of eight FQs decreased in the order: MOX > ENR > ENO ≈ BAL ≈ FLE ≈ OFL ≈ LOM ≈ SPA, which may be correlated with the substituents at positions 7 and 8 of the basic quinolone nucleus and the metabolic capacity. Besides, BCFs were relative with pH-adjusted distribution coefficient (log D), suggesting that molecular status of ionizable compounds strongly influenced the bioconcentration processes. The present study provides important insights for understanding the bioconcentration and tissues distribution of FQs.

Fluoroquinolones in agricultural soils: Multi-temporal variation and risks in Rio de Janeiro upland region

Our main goal was to investigate the potential accumulation of fluoroquinolones (FQs) in agricultural soils over extended periods of land use, predicting leaching and estimating risk quotients for soil microorganisms. Short to long-term of poultry litter fertilization (<1-30 years) were evaluated for enrofloxacin (ENR) and ciprofloxacin (CIP) input, in addition to the emergence of plasmid-mediated quinolone resistance (PMQR) genes. High FQs concentration (range 0.56-100 mg kg^-1) were measured in poultry litter samples. In soils, FQs occurrence and risks have changed over the years. An accumulation trend was observed between short and medium-term fertilized soils (ST and MT soils), reaching a range of 330-6138 μg kg^-1 ENR and 170-960 μg kg^-1 CIP in MT soil, followed by decreased concentrations in long-term fertilized soils (LT soils). The environmental risk assessment showed a high ENR risk quotient (RQ ≥ 1) in ST and MT soils ranging (7-226) and high CIP risk (9-53) in LT soils. The detection of qnrS genes in the area with the lowest FQs concentration emphasizes the importance of a broader approach to environmental assessment, in which not only target compounds are considered. FQs soil-water migration model pointed out a high leaching risk in ST soil. To reduce risks, management measures to decrease antibiotic environmental load should be taken before poultry litter application. In addition, the high weathering of tropical soils contributing to possible fate of antibiotics to water resources through drainage basins should be considered.

Low-Level Antimicrobials in the Medicinal Leech Select for Resistant Pathogens That Spread to Patients

Fluoroquinolones (FQs) and ciprofloxacin (Cp) are important antimicrobials that pollute the environment in trace amounts. Although Cp has been recommended as prophylaxis for patients undergoing leech therapy to prevent infections by the leech gut symbiont Aeromonas, a puzzling rise in Cp-resistant (Cpr) Aeromonas infections has been reported. We report on the effects of subtherapeutic FQ concentrations on bacteria in an environmental reservoir, the medicinal leech, and describe the presence of multiple antibiotic resistance mutations and a gain-of-function resistance gene. We link the rise of CprAeromonas isolates to exposure of the leech microbiota to very low levels of Cp (0.01 to 0.04 µg/ml), <1/100 of the clinical resistance breakpoint for Aeromonas Using competition experiments and comparative genomics of 37 strains, we determined the mechanisms of resistance in clinical and leech-derived Aeromonas isolates, traced their origin, and determined that the presence of merely 0.01 µg/ml Cp provides a strong competitive advantage for Cpr strains. Deep-sequencing the Cpr-conferring region of gyrA enabled tracing of the mutation-harboring Aeromonas population in archived gut samples, and an increase in the frequency of the Cpr-conferring mutation in 2011 coincides with the initial reports of CprAeromonas infections in patients receiving leech therapy.IMPORTANCE The role of subtherapeutic antimicrobial contamination in selecting for resistant strains has received increasing attention and is an important clinical matter. This study describes the relationship of resistant bacteria from the medicinal leech, Hirudo verbana, with patient infections following leech therapy. While our results highlight the need for alternative antibiotic therapies, the rise of Cpr bacteria demonstrates the importance of restricting the exposure of animals to antibiotics approved for veterinary use. The shift to a more resistant community and the dispersion of Cpr-conferring mechanisms via mobile elements occurred in a natural setting due to the presence of very low levels of fluoroquinolones, revealing the challenges of controlling the spread of antibiotic-resistant bacteria and highlighting the importance of a holistic approach in the management of antibiotic use.

Metabolic profile modifications in milk after enrofloxacin administration studied by liquid chromatography coupled with high resolution mass spectrometry

High resolution accurate mass spectrometry (HRMS) operating in full scan MS mode was used in the search and identification of metabolites in raw milk from cows medicated with enrofloxacin. Data consisting of m/z features were taken throughout the entire chromatogram of milk samples from medicated animals and were compared with blank samples. Twenty six different compounds were identified. Some of them were attributed to structures related to enrofloxacin while others were dipeptides or tripeptides. Additionally, enrofloxacin was administered in a controlled treatment for three days. Milk was collected daily from the first day of treatment and until four days after in the search for the identified compounds. The obtained data were chemometrically treated by Principal Component Analysis. Samples were classified by this method into three different groups corresponding to days 1-2, day 3 and days 4-7 considering the different concentration profile evolution of metabolites during the days studied. Tentative metabolic pathways were designed to rationalize the presence of the newly identified compounds.