The present study investigated the residue depletion and WTs of EF and its main metabolite, ciprofloxacin, in largemouth bass after ad libitum administration in commercial fish farming based on statistical approaches. Samples collected at pre-determined time points were assessed using high-performance liquid chromatography. If the concentrations of medicine were less than the quantitative limit, they were set to be half of the limit of quantitative. The terminal elimination of the target compound was assumed to fit a one-compartment model. The statistical methods of Bartlett\'s test and Cochran\'s test were used to inspect the homogeneity of the log-transformed data. The lack-of-fit test and F-test were used to check the linearity of the regression line. Outliers were assessed using standardized residuals. The final WT was estimated using the 95% percentile with a 95% confidence level. The WTs of EF were calculated to be 46, 29, 33, 46, and 20 days for the muscle + skin, plasma, gill, kidney, and liver, respectively. After the risk assessment, the values of the hazard quotient were calculated to be far less than 1, indicating that the risk of residual EF was particularly low in the edible tissues of largemouth bass after medicine depletion for various WTs.

Enrofloxacin (ENRO) and florfenicol (FF) are animal-specific drugs, but they present great harm to human health. Therefore, it is essential to rapidly and accurately detect ENRO and FF in animal-derived foods simultaneously. Herein, dual-template molecular imprinted polymers (MIPs) with specific recognition of ENRO and FF were prepared, meanwhile, the molar ratios of templates to monomer and cross-linker were optimized and then applied as a bionic antibody to experiment. Based on the principle that the fluorescence of QDs could be efficiently quenched by the enzymatic fabrication of Prussian blue nanoparticles (PBNPs), a novel and sensitive fluorescence quenching biomimetic enzyme-linked immunosorbent assay (BELISA) was established for simultaneous detection of ENRO and FF by the conversion of the absorption signal into fluorescent signals. Under optimal conditions, the detection limit (IC15) was 4.64 ng L-1 for ENRO and 1.33 ng L-1 for FF. Besides, matrix interference of chicken, eggs, milk and shrimp samples, was investigated in our study, and the result indicates that all of the sample matrices had a profound impact on the fluorescence of QDs, especially for milk samples (with Im of 94.10 %). After performing the matrix-elimination experiments, chicken, eggs, milk and shrimp samples spiked with ENRO and FF were extracted and detected by this proposed method, with recoveries ranging from 82.70 to 113.48 %. The results correlated well with those obtained using HPLC. In conclusion, the developed method could be an alternative and sensitive method for the simultaneous detection of ENRO and FF in animal-derived foods.

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.

The continuous release of antibiotics into agroecosystems has raised concerns about the potential negative effects of antibiotic residues on crops. In this study, the toxicological effects of enrofloxacin (ENR) on wheat seedlings were analyzed using a combination of morpho-physiological, transcriptomic, proteomic, and metabolomic approaches. ENR inhibited the growth of wheat (Triticum aestivum L.) roots and induced oxidative stress. In particular, ENR downregulated the oxidative phosphorylation pathway, while it enhanced glycolysis and the tricarboxylic acid cycle, thereby regulating the balance of intracellular energy metabolism. In addition, sustained exposure to excessive reactive oxygen species (ROS) resulted in an increase in reduced glutathione (GSH), a slight decrease in ascorbic acid (AsA), and a significant decrease in the ratio of GSH to oxidized glutathione (GSSG), which imbalanced the AsA-GSH cycle. In addition, the resulting increase in abnormal proteins triggered ubiquitin-independent proteasomal degradation pathways. Further, an increase in abscisic acid (ABA) and a decrease in jasmonic acid (JA) and its derivatives alleviated the inhibitory effect of ENR on the growth of wheat roots. In conclusion, direct damage and signaling by ROS, hormonal regulation, a decrease in the GSH to GSSG ratio, and insufficient energy supply were identified as key factors for the significant inhibition of wheat root growth under ENR stress.

Enrofloxacin (EF) is a broad-spectrum and highly efficient antibiotic commonly used for treating diseases in aquatic animals. However, its abuse in aquaculture applications often leads to excess residue in tissues of grass carp (Ctenopharyngodon idella). Hence, this study aimed to estimate the withdrawal time (WT) of EF and its metabolite of ciprofloxacin (CF) administered medicated feed in natural culture environments and conduct a risk assessment. Plasma and tissue samples were gathered at appropriate time points and detected by high-performance liquid chromatography. The data homogeneity was evaluated by Bartlett\'s test and Cochran\'s test. The linearity of the regressed line was evaluated by visual inspection and F test. Outliers were estimated on a normal probability scale by plotting the standardized residual versus their cumulative frequency distribution. Finally, the WT was calculated to be 51 days in muscle + skin based on the maximum residue limit of 100 µg/kg. After 51 days, the concentration of EF and CF fell below 10 µg/kg. The estimated daily intake was calculated to be 0.009 µg/kg/d. Hazard quotient was computed to be 0.002, which was far below one. These results suggested that calculated WT of EF could ensure the safety of products from grass carp for humans.

Microalgae can promote antibiotic removal, which has attracted growing attention. However, its synergistic removal performance with bacteria in antibiotic pollutants is still poorly understood. In this study, firstly, we selected two green algae (Dictyosphaerium sp. and Chlorella sp.) and exposed them to Enrofloxacin (ENR) to observe their extracellular polysaccharides (EPS) concentration dynamic and the removal of antibiotics. Secondly, EPS was extracted and added to in situ lake water (no algae) to investigate its combined effect with bacteria. The results indicate that both Dictyosphaerium sp. and Chlorella sp. exhibited high tolerance to ENR stress. When the biomass of microalgae was low, ENR could significantly stimulate algae to produce EPS. The removal rates of Dictyosphaerium sp. and Chlorella sp. were 15.8% and 10.5%, respectively. The addition of EPS can both alter the microbial community structure in the lake water and promote the removal of ENR. The LEfSe analysis showed that there were significant differences in the microbial marker taxa, which promoted the increase of special functional bacteria for decomposing ENR, between the EPS-added group and the control group. The EPS of Dictyosphaerium sp. increased the abundance of Moraxellaceae and Spirosomaceae, while the EPS of Chlorella sp. increased the abundance of Sphingomonadaceae and Microbacteriaceae. Under the synergistic effect, Chlorella sp. achieved a maximum removal rate of 24.2%, while Dictyosphaerium sp. achieved a maximum removal rate of 28.9%. Our study provides new insights into the removal performance and mechanism of antibiotics by freshwater microalgae in water bodies and contribute to the development of more effective water treatment strategies.

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.

Animals manure and chemical fertilizers are widely applied to agricultural soils to mitigate soil fertility decline resulting from intensive farming practices. However, the use of antibiotics such as ciprofloxacin (CIP) and enrofloxacin (ENR) in these manures introduces certain environmental risks. The sorption of CIP and ENR in soil is influenced by various factors. Soil cations (i.e., Na+, K+, Mg2+, and Ca2+) and artificially introduced ions (NH4+) can affect the sorption behavior of CIP and ENR in alkaline agricultural soils through mechanisms such as ion exchange and competitive sorption. To investigate the effects of ionic strength and ion type on the sorption of antibiotics in alkaline agricultural soil, batch equilibrium experiments were conducted in this study. The results showed that the affinity of alkaline farmland soil to CIP and ENR was poor, and Kd was only 159 L/kg and 89 L/kg, respectively. Increases in temperature and pH inhibited CIP and ENR sorption on soil. Mineral elements in the soil strongly inhibited CIP and ENR sorption. Conversely, NH4+ promoted the Kd values of CIP and ENR by 46% and 221%, respectively. Additionally, under different influencing factors, both the sorption affinity (Kd) and sorption amount of ENR were lower than those of CIP. These findings indicate that ENR has a greater migration potential and poses a greater environmental risk in agricultural soils. Alkaline soil and mineral elements increase the migration potential of CIP, ENR, but the introduction of NH4+ in agricultural production can weaken the migration potential of them.

Dynamic impacts of short-term enrofloxacin (ENR) exposure on juvenile marine fish are not well understood, and the underlying mechanisms remain unclear. We therefore investigated the accumulation and elimination of ENR in the liver of juvenile black seabream Acanthopagrus schlegelii. Meanwhile, the dynamic alterations of biochemical parameters and liver transcriptomes after short-term bath immersion and withdrawal treatment were explored. The results indicated that the contents of ENR in the liver were significantly increased after bath administration for 24 h, and then quickly declined to very low concentrations along with the decontamination time increasing. Judging from the changes in biochemical indicators and liver transcriptomic alterations, 0.5 and 1 mg/L ENR exposure for 24 h triggered oxidative stress, impairment of immune system, as well as aberrant lipid metabolism via differential molecular pathways. Interestingly, biochemical and transcriptome analysis as well as integrated biomarker response (IBR) values showed that more significant changes appeared in 1 mg/L ENR group at decontamination periods, which indicated that the impact of high dose ENR on juvenile A. schlegelii may persist even after depuration for 7 days. These results revealed that the risk of short-term bath of 1 mg/L ENR should not be overlooked even after depuration period. Therefore, attention should be paid to the dosage control when administering the drug to juvenile A. schlegelii, and the restoration of physiological disturbance may be an important factor in formulating a reasonable treatment plan.