Concentrations Of Enrofloxacin Research Articles

Flumequine, a fluoroquinolone in disguise

Fluoroquinolone resistance in E. coli isolates from livestock in Europe remains high despite EMA restrictions on fluoroquinolone use in animals. However, flumequine, a quinolone not classified as a fluoroquinolone by various regulatory bodies, is still used in livestock in the Netherlands, Belgium, Greece and France. We investigated whether flumequine selects for the same resistance mechanisms in E. coli. Resistant and non-resistant E. coli isolates were obtained from caecal fermentation assays and broilers exposed to concentrations of flumequine and enrofloxacin. Flumequine usage leads to an approximately 3-fold increase in resistant E. coli in the caecal fermentation, similar to enrofloxacin. In vitro exposure to both flumequine and enrofloxacin revealed the same amino acid substitutions (S83L, D87G) in GyrA. Additionally, the same resistance-causing substitutions were found in phenotypically resistant E. coli isolates from broilers treated with either enrofloxacin or flumequine. Flumequine induces similar resistance mechanisms as enrofloxacin, warranting equivalent restrictions on its use.

Removal of enrofloxacin as well as nutrients in mariculture water by Sesuvium portulacastrum system: Insights for biodegradation, ecotoxicity of enrofloxacin

Antibiotic contamination and eutrophication in mariculture have become problems that cannot be ignored, and enrofloxacin (ENR), as an example, is especially widely used in mariculture. This study firstly revealed that Sesuvium portulacastrum, a plant with world-wide distribution in coastal zones, with its rhizosphere microorganisms, could remove ENR as well as nutrients. The S. portulacastrum system could degrade ENR to small-molecule products 1,2,3,4-tetrahydroquinolin-4-ol and (2,4-dihydroxyphenyl)-cyclopropylamine. And there were 81.3–39.2 % removals of ENR with 0.01-100 mg/L. Although ENR significantly influenced functions of rhizosphere microbial community, like decreasing nitrogen fixation, shifting trophic strategies from phototrophy to chemoheterotrophy, nutrients (NH4+-N, NO2−-N, NO3−-N and total dissolved phosphorus) removal of S. portulacastrum system was essentially unaffected at low ENR concentration (< 1 mg/L). The removal mechanism of S. portulacastrum system was explored. Neither of the isolated root exudates and rhizosphere bacteria could degrade ENR, however, without rhizosphere bacteria, ENR removal rate would decrease. Root proteins including oxidase, decarboxylase, dehydrogenase, such as laccase, isocitrate dehydrogenase, delta-1-pyrroline-5-carboxylate dehydrogenase were overexpressed. Additionally, endocytosis is a pathway for antibiotics to enter S. portulacastrum. This study demonstrated that S. portulacastrum system could be used for remediation of antibiotics-nutrients combined pollution, and deepened understanding the antibiotic removal mechanism of macrophytes in mariculture, moreover, provided new macroplant species and a theoretical basis for antibiotics removal in aquatic systems.

The stratified response of heterotrophic, autotrophic or mixotrophic denitrification to enrofloxacin stress along different filling heights in up-flow fixed-bed bioreactors

Antibiotics frequently exist in nitrate wastewater and seriously threaten biological denitrification. This study investigated the impact of enrofloxacin (ENR) on autotrophic, heterotrophic, and mixotrophic denitrification processes at various filling heights. The experiments were conducted across four consecutive phases with ENR concentrations of 0, 0.1, 1, and 10 mg/L. As the influent ENR concentration increased, the denitrification performance of the FeS2-based autotrophic denitrification (PAD) system was significantly inhibited at different filling heights, with nitrate removal efficiency (NrE) dropping to 30.42 %. In contrast, the polycaprolactone (PCL)-based heterotrophic denitrification (PHD) and mixotrophic denitrification (PAD+PHD) systems only affected NrE in the lower layer, whereas the middle and upper layers maintained high NrE levels, largely unaffected by ENR stress, reaching up to 98.28 % and 94.02 % respectively. Sulfate reduction was more prominent in the upper and middle layers of the mixotrophic denitrification bioreactor (PHD system). Bacterial diversity indices initially increased and then decreased as ENR concentration rose from 0 to 10 mg/L, with the PHD system showing lower diversity compared to the PAD system. Redundancy analysis (RDA) revealed that the relative abundances of Proteobacteria and Actinobacteriota in the PAD system, and Bacteroidota and Firmicutes in the PHD system, were negatively correlated with ENR concentration. Overall, the PAD system experienced significant stress from ENR at various filling heights, whereas the upper-middle layer of the PHD system demonstrated greater resistance. This highlighted the impact of antibiotic contamination along with the performance of different filling heights and emphasized the need for tailored strategies in wastewater treatment.

Pharmacokinetics of Enrofloxacin and Its Metabolite Ciprofloxacin in Nanyang Cattle.

The objective of this study was to determine the pharmacokinetics of enrofloxacin and its metabolite, ciprofloxacin, in Nanyang cattle after a single intravenous (IV), and intramuscular (IM) administration of enrofloxacin at 2.5 mg/kg body weight (BW). Blood samples were collected at predetermined time points. Enrofloxacin and ciprofloxacin concentrations in plasma were simultaneously determined using a high-performance liquid chromatography (HPLC) assay method and subjected to a non-compartmental analysis. After IV administration, enrofloxacin had a mean (±SD) volume of distribution at steady state (VSS) of 1.394 ± 0.349 L/kg, a terminal half-life (t1/2λz) of 3.592 ± 1.205 h, and a total body clearance (Cl) of 0.675 ± 0.16 L/h/kg. After IM administration, enrofloxacin was absorbed relatively slowly but completely, with a mean absorption time (MAT) of 6.051 ± 1.107 h and a bioavailability of 99.225 ± 7.389%. Both compounds were detected simultaneously in most plasma samples following both routes of administration, indicating efficient biotransformation of enrofloxacin to ciprofloxacin. After IV injection, the peak concentration (Cmax) of ciprofloxacin was 0.315 ± 0.017 μg/mL, observed at 0.958 ± 0.102 h. Following IM injection, the corresponding values were 0.071 ± 0.006 μg/mL and 3 ± 1.095 h, respectively. Following IV and IM administration, the conversion ratio of enrofloxacin to ciprofloxacin was calculated as 59.2 ± 9.6% and 31.2 ± 7.7%, respectively. The present results demonstrated favorable pharmacokinetic profiles for enrofloxacin, characterized by complete absorption with relatively slow kinetics, extensive distribution, efficient biotransformation to ciprofloxacin, and prolonged elimination in Nanyang cattle.

Adsorption/desorption of enrofloxacin in farmland soil as the effect of pH and coexisting ions: implications for enrofloxacin fate and risk in loess soil.

Fluoroquinolone antibiotics have been extensively used in clinical treatments for human and animal diseases. However, their long-term presence in the environment increases the risk of producing resistance genes and creates a potential threat to ecosystems and the health of humans and animals. Batch equilibrium experiments were utilized to investigate the adsorption and retention behavior and mechanism of the quinolone antibiotic enrofloxacin (ENR) in farmland soil in North China. The adsorption and desorption kinetics of ENR in soil were best fitted by pseudo-second-order model (R2 > 0.999). Both the adsorption and desorption processes of ENR in soil reached equilibrium in 1h. The desorption amounts of ENR were significantly lower than the adsorption amounts, with the hysteresis coefficient (HI) being less than 0.7. The adsorption thermodynamic process of ENR followed the Linear and Freundlich models (0.965 < R2 < 0.985). Hydrophobic distribution and heterogeneous multimolecular layer adsorption were identified as critical factors in the adsorption process. The adsorption amount of ENR gradually decreased with increasing temperature and the initial concentration of ENR. The adsorption rate of ENR was above 80%, while the desorption rate remained below 15%, indicating strong retention ability. The adsorption rate of ENR in soil decreased with increasing pH, the adsorption rate reached 98.3% at pH 3.0 but only 31.5% at pH 11. The influence of coexisting ions on adsorption primarily depended on their properties, such as ion radius, ionic strength, and hydrolysis properties, and the inhibition of adsorption increased with increasing ionic strength. These findings contribute to understanding the fate and risk of veterinary antibiotics in loess soil in North China.

Visual fluorescent detection of enrofloxacin based on hollow EH-SiO2@ covalent organic framework nanospheres

Covalent organic frameworks (COFs) are porous crystalline polymers. Due to aggregation caused quenching (ACQ) effect caused by the strong π-π interactions in stacked layers, weak fluorescence or no luminescence is caused. Here, a series of core–shell structure of SiO2@COFTFP-AMPD (2,4,6-triformylphloroglucinol: TFP, 2,2′-azobis(2-methylpropionamidine) dihydrochloride: AMPD) with different morphologies was prepared by changing temperature and time using –NH2-SiO2 nanospheres (NPs) as templates. Without the need to be prepared by adding HF or strong alkali, the hollow spherical EH-SiO2@COFTFP-AMPD not only inhibited ACQ of COFTFP-AMPD, but also achieved dual emission at 438 and 550 nm. The structure served as ratiometric fluorescent probe for visual detection of Enrofloxacin (ENR) with a detection range of 2.41 nM-0.48 μM and a detection limit as low as 0.80 nM. The concentration of ENR in unknown samples can be detected not only by stripe and gel. Moreover, with the RGB numerical analysis function of smartphone App, real-time visual detection of ENR can be realized, which possesses potential in food health and safety.

Residue depletion of enrofloxacin and flumequine in feathers of broilers based on quantitative UHPLC-MS/MS detection

To explore potential factors contributing to high fluoroquinolone resistance levels, it is essential to develop analytical methods capable of detecting residues and trace amounts of antibiotic use in broilers. The aim of the present study was to develop and in-house validate a sensitive UHPLC-MS/MS method capable of determining enrofloxacin (ENR) and flumequine (FLU) residues at slaughter age (day 45) when the animals were treated with these antimicrobials one day after hatching. Residue depletion of ENR and FLU in feathers was also assessed. Two experimental trials were performed, both consisting of 5 different treatment groups. In the first trial animals were treated with ENR and in the second one with FLU. The developed method was successfully validated and was found to be sensitive enough to detect residues of fluoroquinolones in the feathers up until slaughter age in all treatment groups. Average ENR concentration on day 45 was 10 ng g−1 feather after drinking water treatment, with all concentrations above the limit of quantification (LOQ) of 5 ng g−1 feather. For FLU average concentration on day 45 after drinking water administration was 4 ng g−1 feather, with an LOQ of 1 ng g−1 feather. Therefore, the method is suited for application to monitor fluoroquinolone use in broilers.

Impact of Prophylactic Antibiotic Use in Ornamental Fish Tanks on Microbial Communities and Pathogen Selection in Carriage Water in Hong Kong Retail Shops.

Antibiotics are routinely added to ornamental fish tanks for treating bacterial infection or as a prophylactic measure. However, the overuse or subtherapeutical application of antibiotics could potentially facilitate the selection of antibiotic resistance in bacteria, yet no studies have investigated antibiotic use in the retail ornamental fish sector and its impact on microbial communities. The present study analyzed the concentrations of twenty antibiotics in the carriage water (which also originates from fish tanks in retail shops) collected monthly from ten local ornamental fish shops over a duration of three months. The antibiotic concentrations were correlated with the sequenced microbial community composition, and the risk of resistance selection in bacteria was assessed. Results revealed that the detected concentrations of tetracyclines were the highest among samples, followed by fluoroquinolones and macrolides. The concentrations of oxytetracycline (44.3 to 2,262,064.2 ng L-1) detected across three months demonstrated a high risk for resistance selection at most of the sampled shops. Zoonotic pathogens (species of Rhodococcus, Legionella, and Citrobacter) were positively correlated with the concentrations of oxytetracycline, tetracycline, chlortetracycline, and enrofloxacin. This suggests that antibiotic use in retail shops may increase the likelihood of selecting for zoonotic pathogens. These findings shed light on the potential for ornamental fish retail shops to create a favorable environment for the selection of pathogens with antibiotics, thereby highlighting the urgent need for enhanced antibiotic stewardship within the industry.

Pentacenequinone-Modulated 2D GdSn-PQ Nanosheets as a Fluorescent Probe for the Detection of Enrofloxacin in Biological and Environmental Samples.

The fate and effects of fluoroquinolone antibacterial (FQ) on the environment are important since there appears to be a surge in FQ resistance like enrofloxacin (ENR) in both environmental and clinical organisms. Numerous reports indicate that the sensing capabilities of these antibiotics need to be improved. Here, we have investigated the interaction of ENR with our synthesized pentacenequinone-modulated gadolinium-tin (GdSn-PQ) nanosheets and the formation of intermolecular interactions that caused the occurrence of aggregation-induced emission enhancement. The concept for designing hybrid metallic nanosheets comes from the unique features inherited from the parent organic precursor. Due to the distinct interaction between ENR and GdSn-PQ, the interstate conversion (ISC) between GdSn-PQ and ENR induces a significant wavelength shift in photoluminescence (PL), improving reliability, selectivity, and visibility compared to quenching- or AIEE-based methods without peak shifts, allowing for highly sensitive and visually detectable analyses. The fluorescence signal of GdSn-PQ exhibited a linear relationship (R2 = 0.9911), with the added ENR concentrations ranging from 5 to 90 nM, with a detection limit of 0.10 nM. We have demonstrated its potential and wide use in the detection of ENR in biological samples (human urine and blood serum) and environmental samples (tap water and seawater) with a recovery rate of 98- 108%. The current approach has demonstrated that the 2D GdSn-PQ nanosheet is a novel and powerful platform for future biological and environmental studies.

Interaction between Enrofloxacin and Three Essential Oils (Cinnamon Bark, Clove Bud and Lavender Flower)-A Study on Multidrug-Resistant Escherichia coli Strains Isolated from 1-Day-Old Broiler Chickens.

Avian pathogenic Escherichia coli (APEC) causes a variety of infections outside the intestine. The treatment of these infections is becoming increasingly difficult due to the emergence of multi-drug resistant (MDR) strains, which can also be a direct or indirect threat to humans as consumers of poultry products. Therefore, alternative antimicrobial agents are being sought, which could be essential oils, either administered individually or in interaction with antibiotics. Sixteen field isolates of E. coli (originating from 1-day-old broilers) and the ATCC 25922 reference strain were tested. Commercial cinnamon bark, clove bud, lavender flower essential oils (EOs) and enrofloxacin were selected to assess the sensitivity of the selected E. coli strains to antimicrobial agents. The checkerboard method was used to estimate the individual minimum inhibitory concentration (MIC) for each antimicrobial agent as well as to determine the interactions between the selected essential oil and enrofloxacin. In the case of enrofloxacin, ten isolates were resistant at MIC ≥ 2 μg/mL, three were classified as intermediate (0.5-1 μg/mL) and three as sensitive at ≤0.25 μg/mL. Regardless of the sensitivity to enrofloxacin, the MIC for cinnamon EO was 0.25% v/v and for clove EO was 0.125% v/v. All MDR strains had MIC values for lavender EO of 1% v/v, while drug-sensitive isolates had MIC of 0.5% v/v. Synergism between enrofloxacin and EO was noted more frequently in lavender EO (82.35%), followed by cinnamon EO (64.7%), than in clove EO (47.1%). The remaining cases exhibited additive effects. Owing to synergy, the isolates became susceptible to enrofloxacin at an MIC of ≤8 µg/mL. A time-kill study supports these observations. Cinnamon and clove EOs required for up to 1 h and lavender EO for up to 4 h to completely kill a multidrug-resistant strain as well as the ATCC 25922 reference strain of E. coli. Through synergistic or additive effects, blends with a lower than MIC concentration of enrofloxacin mixed with a lower EO content required 6 ± 2 h to achieve a similar effect.

Effects of four antibiotics on the photosynthetic light reactions in the green alga Chlorella pyrenoidosa

Antibiotics are ubiquitously present in aquatic environments, posing a serious ecological risk to aquatic ecosystems. However, the effects of antibiotics on the photosynthetic light reactions of freshwater algae and the underlying mechanisms are relatively less understood. In this study, the effects of 4 representative antibiotics (clarithromycin, enrofloxacin, tetracycline, and sulfamethazine) on a freshwater alga (Chlorella pyrenoidosa) and the associated mechanisms, primarily focusing on key regulators of the photosynthetic light reactions, were evaluated. Algae were exposed to different concentrations of clarithromycin (0.0–0.3 mg/L), enrofloxacin (0.0–30.0 mg/L), tetracycline (0.0–10.0 mg/L), and sulfamethazine (0.0–50.0 mg/L) for 7 days. The results showed that the 4 antibiotics inhibited the growth, the photosynthetic pigment contents, and the activity of antioxidant enzymes. In addition, exposure to clarithromycin caused a 118.4 % increase in malondialdehyde (MDA) levels at 0.3 mg/L. Furthermore, the transcripts of genes for the adenosine triphosphate (ATP) - dependent chloroplast proteases (ftsH and clpP), genes in photosystem II (psbA, psbB, and psbC), genes related to ATP synthase (atpA, atpB, and atpH), and petA (related to cytochrome b6/f complex) were altered by clarithromycin. This study contributes to a better understanding of the risk of antibiotics on primary producers in aquatic environment.

Magnetic nanoparticles-based electrochemical aptasensor for the detection of enrofloxacin in chicken

Enrofloxacin (ENR) is widely applied in preventing and treating animal diseases and hence directly passed into animal-derived foods. Therefore, the detection of this drug in food samples must be strengthened to ensure food safety. In this work, a simple, sensitive electrochemical aptasensor for the detection of ENR was fabricated by using magnetic nanoparticles (MNPs) as carriers. The ENR aptamer was modified on the surface of MNPs to capture the ENR target or a biotin-complementary strand and then recognize streptavidin-horse radish peroxidase. Subsequently, the resulting MNPs were easily transferred onto the surface of magnetic glassy carbon electrode with the help of its integral magnet. Under optimal experimental conditions, a linear relationship between the variable of LSV current and the logarithm of ENR concentration in the range of 0.01–100 ng/mL was obtained with the limit of detection at 4.9 pg/mL. In addition, this method exhibited good stability, selectivity, reproducibility and was successfully applied in detecting ENR in spiked chicken samples with recoveries of 100.70%–108.96%. The proposed method is easy to fabricate and process; it is particularly suitable for food sample pretreatment and is beneficial in removing the interference of a complex matrix.

Antibiotic residues in commercial freshwater fish from southeast China: distribution and human health risk assessment.

We investigated 14 antibiotic residues in 8 marketed freshwater fish species from southeast China and estimated the associated health risks to local consumers. The antibiotic residues were determined by UPLC-MS/MS. Our findings revealed widespread distribution of quinolones (QNs), tetracyclines (TCs), and chloramphenicols (CAPs) in the freshwater fish. Notably, the average concentrations of enrofloxacin and ciprofloxacin reached levels as high as 62.5μg/kg wet weight (ww) and 11.7μg/kg ww, respectively, and detection frequencies were 68.7% for enrofloxacin and 31.6% for ciprofloxacin. Additionally, we detected chloramphenicol, a prohibited antibiotic, in samples with a detection frequency of 0.76%. Among the fish species, the mean concentration of total antibiotic residues was highest in bluntnose black bream (263.3μg/kg), followed by English perch (52.4μg/kg), crucian carp (46.3μg/kg), black carp (28.6μg/kg), yellowcheek carp (21.0μg/kg), grass carp (15.3μg/kg), bighead carp (3.78μg/kg), and mandarin fish (3.69μg/kg). We estimated the daily intake values of these antibiotic residues which were lower than the acceptable daily intake values and hazard indexes were much less than 1. It indicates that there is very low direct health risk to consumers. Despite that, investigation on the chronic impact, such as antibiotic-resistant bacteria, gut microbiota disruption, and allergic reactions, is urgently needed.

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.Graphical

Enrofloxacin pharmacokinetics in yellow catfish (Pelteobagrus fulvidraco): A comparative analysis of oral, intramuscular, and bath administration.

Enrofloxacin (ENR) residues in yellow catfish (Pelteobagrus fulvidraco) often exceed the standard due to excessive use. This study explored the pharmacokinetics of ENR and its metabolite ciprofloxacin (CIP) in yellow catfish following a single dose of 10 mg/kg body weight via intramuscular injection (IM), oral gavage (PO), or a 5-h drug bath at 10 mg/L and 25°C. High-performance liquid chromatography-mass spectrometry was used to determine the ENR and CIP concentrations in various tissues. The highest ENR concentration occurred with IM administration, peaking at 4.124 mg/L in the plasma, 8.359 mg/kg in the kidney, 6.272 mg/kg in the liver, and 5.192 mg/kg in the muscle. However, PO administration resulted in the longest metabolic time, with elimination half-lives of 56.47 h in plasma, 86.43 h in the kidney, 76.25 h in the liver, and 64.75 h in muscle. Additionally, the area under the concentration-time curve values for IM, PO, and bath administration in yellow catfish plasma were 108.36, 88.96, and 22.08 mg·h/L, respectively. These results indicate the effectiveness of all three administration methods in treating bacterial diseases in yellow catfish. The selection of an appropriate administration method depends on the minimal inhibitory concentration of ENR against pathogenic bacteria. Yellow catfish subjected to PO and IM administration require longer resting periods before they can be marketed than those receiving drug bath administration.

Intramuscular therapeutic doses of enrofloxacin affect microbial community structure but not the relative abundance of fluoroquinolones resistance genes in swine manure

Livestock manure is a major source of veterinary antibiotics and antibiotic resistance genes (ARGs). Elucidation of the residual characteristics of ARGs in livestock manure following the administration of veterinary antibiotics is critical to assess their ecotoxicological effects and environmental contamination risks. Here, we investigated the effects of enrofloxacin (ENR), a fluoroquinolone antibiotic commonly used as a therapeutic drug in animal husbandry, on the characteristics of ARGs, mobile genetic elements, and microbial community structure in swine manure following its intramuscular administration for 3 days and a withdrawal period of 10 days. The results revealed the highest concentrations of ENR and ciprofloxacin (CIP) in swine manure at the end of the administration period, ENR concentrations in swine manure in groups L and H were 88.67 ± 45.46 and 219.75 ± 88.05 mg/kg DM, respectively. Approximately 15 fluoroquinolone resistance genes (FRGs) and 48 fluoroquinolone-related multidrug resistance genes (F-MRGs) were detected in swine manure; the relative abundance of the F-MRGs was considerably higher than that of the FRGs. On day 3, the relative abundance of qacA was significantly higher in group H than in group CK, and no significant differences in the relative abundance of other FRGs, F-MRGs, or MGEs were observed between the three groups on day 3 and day 13. The microbial community structure in swine manure was significantly altered on day 3, and the altered community structure was restored on day 13. The FRGs and F-MRGs with the highest relative abundance were qacA and adeF, respectively, and Clostridium and Lactobacillus were the dominant bacterial genera carrying these genes in swine manure. In summary, a single treatment of intramuscular ENR transiently increased antibiotic concentrations and altered the microbial community structure in swine manure; however, this treatment did not significantly affect the abundance of FRGs and F-MRGs.

A colorimetric-aptamer-based assay for the determination of enrofloxacin through triggering the aggregation of gold nanoparticles.

Although enrofloxacin (ENR) is a widely used broad-spectrum antibiotic in veterinary medicine, its residues in animals can pose a risk to human health. Thus, we developed a new method for detecting ENR based on aptamers and AuNPs. In the absence of ENR, the aptamers attached to the surface of the AuNPs via electrostatic interactions to protect the AuNPs from NaCl, and the solution remained red. Conversely, the aptamer bonded with ENR, leading the aptamer to detach from the AuNP surface, and the color of the solution changed from red to blue. Based on this principle, ENR can be qualitatively detected by the naked eye and quantitatively detected by measuring the absorbance ratio at 650 nm and 530 nm. The experimental results showed a good linear relationship within the ENR concentration range of 0-400 nM, with a limit of detection (LOD) of 1.72 nM, which is satisfactory for detection in food safety. Additionally, this method has also been successfully applied to the detection of ENR in tap water, river water, milk, serum and urine, with good recovery rates and RSD values of less than 7%, indicating its great potential for ENR detection in environmental water samples. More importantly, the combination of this method with a smartphone platform provided great convenience for on-site and visual detection of ENR, offering promising applicability prospects.

Facile fabrication of Fe3O4@UiO-66-NH2/popcorn-like gold nanoparticles based SERS substrate for selective enrichment and real-time detection of residual enrofloxacin in milk

In this study, a magnetic metal-organic frameworks (MOFs) based hybrid substrate was designed and fabricated for SERS detection of enrofloxacin (ENR) in milk. The magnetic MOF (Fe3O4@UiO-66-NH2) was synthesized by a facile microwave-assisted method, then loaded with popcorn-like Au nanoparticles (NPs) through electrostatic interaction. The as-prepared SERS substrate (Fe3O4@UiO-66-NH2/Au NPs) integrated the abundant hot spots of popcorn-like Au NPs with porous Fe3O4@UiO-66-NH2, which greatly improved its SERS activity and stability. More importantly, benefiting from the fingerprint characteristics of SERS and adsorption performance of Fe3O4@UiO-66-NH2, the SERS substrate exhibited high selectivity and sensitivity in detecting ENR. Under the optimal detection condition, a good linearity (R2 = 0.996) was obtained with ENR concentration of 1.0 × 10−9–1.0 × 10−6 M in spiked milk, the LOD was as low as 5.26 × 10−10 M, and the recoveries were in the range of 76.1–86.1 % at three different spiking levels. The whole detection process including sample pretreatment took about 50 min, which indicating that the prepared substrate has great potential in sensitive and real-time detection of ENR in milk.

Deciphering the response of heterotrophic, autotrophic and mixotrophic denitrification to enrofloxacin stress: Performance, denitrifying community and antibiotic resistance genes

Antibiotics frequently coexist with nitrate (NO3−-N) in wastewater. This study systematically explored the negative effects of enrofloxacin (ENR) on the microbial performance of autotrophic, heterotrophic and mixotrophic denitrification processes under parallel conditions. The ENR concentration was set at 0, 0.1, 1 and 10 mg/L for four phases in sequence. As the influent ENR concentration increased, the nitrate removal efficiency (NrE) in the pyrite-based autotrophic denitrification (PAD) system declined gradually to 11.08% (minimum) and the expressed narG/H/I and napA/B genes decreased. However, the NrE in the polycaprolactone-based heterotrophic denitrification (PHD) and mixotrophic denitrification systems declined slightly (the lowest NrE: 88.10% and 85.28%, respectively), and the expressed narG/H/I (0–1 mg/L) and napA/B genes increased gradually in the PHD system. The removal pathway of ENR was mainly through adsorption by substrates and/or biofilms rather than through biodegradation. Increasing the concentration of ENR (0–10 mg/L) reduced the relative abundance of functional genera (Syntrophomonas, Lentimicrobiaceae_unclassified, Bacteroidetes_vadinHA17_unclassified, and Clostridium) capable of degrading polymers in the PHD system, but elevated the relative abundance of the dominant genus Thiobacillus in the PAD system. Network analyses showed that Thiobacillus in the PAD system as well as Anaerolineaceae_unclassified and Simplicispira in the PHD system were resistant to ENR stress.

Evaluation of Tetracycline and Enrofloxacin Residues in Bovine Milk in Tehran Utilizing ELISA and HPLC Methods

Background: Milk is regarded as one of the most sources of nutrition in the world and has a high value for individual's health. Milk is consumed by sensitive groups including pregnant women, older adults, and children. Therefore, the significance of antibiotic on human health makes it crucial to monitor their existence in food. This investigation aims to evaluate enrofloxacin and tetracycline in the raw and pasteurized milk in Tehran.&#x0D; Methods: In this cross-sectional study, 112 raw and 112 pasteurized milks were accumulated in spring and winter from six reputable brands and traditional dairy stores in Tehran from December 2021 until May 2022 for six months, and antibiotic residues were examined by Immunosorbent Assay and High-Performance Liquid Chromatography techniques.&#x0D; Results: The findings indicated that the prevalence of tetracycline in raw and pasteurized milk was 41.07 and 26.78% in spring and 85.71 and 35.71% in winter, respectively. The median concentration of tetracycline was 33.27 and 22.65 ppb in spring and 55.81 and 21.91 ppb in winter, respectively. The prevalence of enrofloxacin in raw milk and pasteurized milk samples were 33.92 and 14.28% in spring and 64.28 and 32.14% in winter, respectively. The median concentrations of enrofloxacin were 9.13 and 9.38 ppb in spring and 10.57 and 11.23 ppb in winter, respectively. The raw and pasteurized milk samples collected in winter had higher percentage of antibiotic residue in terms of enrofloxacin than samples collected in spring (p&lt;0.05). Furthermore, the quantity of tetracycline antibiotic in raw milk was significantly higher in winter than in spring (p=0.002). However, the pasteurized milk fails to have significant difference between two seasons. The finding showed the tetracycline and enrofloxacin in all samples were less than 100 ppb (standard limit), and there is no significant difference with the standard limit.&#x0D; Conclusion: Based on the obtained results, monitoring the antibiotic residues in milk, controlling and minimizing these residues for human health are regarded crucial.