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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 (IC 15) 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 I m 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. Schematic illustration of fluorescence quenching BELISA based on QDs. [Display omitted] • A novel QDs-based on biomimetic fluorescence immunoassays was developed. • The proposed method was applied for simultaneous detection of ENRO and FF. • Matrix interference of four samples on this proposed method was explored. • The results showed high agreement between the proposed method and HPLC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pd-MoS 2 presented state-of-the-art specific activity in FLO removal via a H* ads -mediated EHDH process. • Pd-MoS 2 was still robust for FLO degradation in practical industrial wastewater treatment. • Atomic Pd working jointly with MoS 2 formed a dual-active-center for the enhanced EHDH activity. • The H* ads -mediated EHDH process dramatically decreased the toxicity of FLO by breaking C-X bonds. The widespread discharge of halogenated organic pollutants (HOPs) in wastewater brings significant risks to the environment and human health due to potent high toxicity, antibacterial activity, and strong biodegradation resistance. Adsorbed atomic hydrogen (H* ads)-mediated electrocatalytic hydrodehalogenation (EHDH) has been recognized as an efficient strategy for HOPs removal through selectively breaking carbon-halogen bonds. In this work atomic Pd uniformly anchored on molybdenum disulfide (denoted as Pd-MoS 2) was synthesized through a facile hydrothermal method and found with state-of-the-art specific activity in florfenicol (FLO) removal via the H* ads -mediated EHDH process. Pd-MoS 2 completely dehalogenated (∼100 %) FLO within 30 min at a rate constant of 0.15 min−1, which was 6.0, 6.5 and 33.1 times the value of MoS 2 , Pd/C and carbon paper samples, respectively. Notably, the toxicity of the wastewater was reduced to 1/6 of its original value after the treatment. Moreover, Pd-MoS 2 presented superior catalytic stability in five successive cycles. Furthermore, Pd-MoS 2 was also robust in complex water environment with practical applicability for industrial wastewater treatment. A dual-active-center mechanism with enhanced H* ads production capacity and the improved H* ads utilization efficiency was contributed to the increased EHDH activity on Pd-MoS 2. [ABSTRACT FROM AUTHOR]

Florfenicol is a broad-spectrum and bacteriostatic antibiotic with a time-dependent killing action. It is commonly used to treat respiratory diseases in goats in an extra-label manner. This study aimed to determine the plasma pharmacokinetics and milk residue depletion profiles and calculate the milk withdrawal interval (WDI) of florfenicol and its main metabolite florfenicol amine in lactating goats. Five healthy lactating goats were administered with 40 mg/kg florfenicol by subcutaneous injection, twice, 96 h apart. Plasma and milk samples were collected up to 864 h post the first injection. Non-compartmental analysis was used to estimate the plasma pharmacokinetic parameters. Milk WDIs were calculated using the U.S. Food and Drug Administration (FDA) method and European Medicines Agency (EMA) method. A Monte Carlo simulation was performed to generate simulated data for five virtual animals to meet the data requirement of the FDA method. The calculated milk WDIs based on florfenicol, florfenicol amine, and the combined (the sum of florfenicol and florfenicol amine) were 720.28, 690.45, and 872.69 h after the last injection using the FDA method. In conclusion, this study improves our understanding on the plasma pharmacokinetics and milk residue depletion kinetics of florfenicol and florfenicol amine in lactating ruminants after subcutaneous injections. • Pharmacokinetics of florfenicol in plasma and milk were studied in goats. • Goats received 40 mg/kg florfenicol via subcutaneous injections twice 96 h apart. • Milk withdrawal interval (WDI) based on florfenicol was 720.28 h using FDA method. • Milk WDI based on sum of florfenicol and florfenicol amine was 872.69 h. • The results help derive extralabel milk WDIs of florfenicol in lactating goats. [ABSTRACT FROM AUTHOR]

• Florfenicol half-antigen transformed; 8 specific monoclonal antibodies identified. • Monoclonal antibodies against florfenicol were coupled with quantum dots. • New method detects florfenicol in foods and pig feed with heightened sensitivity. • Method aligns with HPLC-MS/MS, quantitatively detecting florfenicol. Florfenicol (F), an antimicrobial agent exclusive to veterinary use within the chloramphenicol class, is extensively applied as a broad-spectrum remedy for animal diseases. Despite its efficacy, concerns arise over potential deleterious residues in animal-derived edibles, posing threats to human health. This study pioneers an innovative approach, introducing a quantum dot fluorescence-based immunoassay (FLISA) for the meticulous detection of F residues in animal-derived foods and feeds. This method demonstrates heightened sensitivity, with a detection limit of 0.3 ng/mL and a quantitative detection range of 0.6–30.4 ng/mL. Method validation, applied to diverse food sources, yields recoveries from 90.4 % to 109.7 %, featuring RSDs within 1.3 % to 8.7 %, the results showed high consistency with the national standard HPLC-MS/MS detection method. These findings underscore the method's accuracy and precision, positioning it as a promising tool for swift and reliable F residue detection, with substantial implications for fortifying food safety monitoring. [ABSTRACT FROM AUTHOR]

The effects of co-exposure to antibiotics and microplastics in agricultural systems are still unclear. This study investigated the effects of florfenicol (FF) and polystyrene microplastics (PS-MPs) on photosynthetic carbon assimilation in rice seedlings. Both FF and PS-MPs inhibited photosynthesis, while PS-MPs can alleviate the toxicity of FF. Chlorophyll synthesis genes (HEMA , HEMG , CHLD , CHLG , CHLM , and CAO) were down-regulated, whereas electron transport chain genes (PGR5 , PGRL1A , PGRL1B , petH , and ndhH) were up-regulated. FF inhibited linear electron transfer (LET) and activated cyclic electron transfer (CET), which was consistent with the results of the chlorophyll fluorescence parameters. The photosynthetic carbon assimilation pathway was altered, the C3 pathway enzyme Ribulose1,5-bisphosphatecarboxylase/oxygenase (RuBisCO) was affected, C4 enzyme ((phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK), malate dehydrogenase (MDH), and phosphoenolpyruvate carboxylase (PEPC))) and related genes were significantly up-regulated, suggesting that the C3 pathway is converted to C4 pathway for self-protection. The key enzymes involved in photorespiration, glycolate oxidase (GO) and catalase (CAT), responded positively, photosynthetic phosphorylation was inhibited, and ATP content and H+-ATPase activity were suppressed, nutrient content (K, P, N, Ca, Mg, Fe, Cu, Zn, Mn, and Ni) significantly affected. Transcriptomic analysis showed that FF and PS-MPs severely affected the photosynthetic capacity of rice seedlings, including photosystem I, photosystem II, non-photochemical quenching coefficients, and photosynthetic electron transport. [Display omitted] • Florfenicol and microplastic affected light and carbon responses in rice seedlings. • Microplastics reduce the toxicity of florfenicol. • Florfenicol interferes with electron transfer, inhibits LET, and activates CET. • C3 pathway converse to C4 pathway under florfenicol stress. • The content of nutrient elements decreased under florfenicol stress. [ABSTRACT FROM AUTHOR]

• Florfenicol metabolites synthesized with standard lab techniques. • High linearity (>0.99) and ±10 % accuracy confirmed in fish analysis. • Consistent detection of florfenicol metabolites in treated fish fillets. • Developed synthesis and SPE-UHPLC-MS/MS methods aids fish drug metabolism studies. This study concerns the synthesis of the florfenicol (FF) metabolites florfenicol amine (FFA), florfenicol alcohol (FFOH), and monochloroflorfenicol (FFCl), for their subsequent use as reference standards in On-line solid-phase extraction-ultra high-performance liquid chromatography-tandem mass spectrometry (SPE-UHPLC-MS/MS) analysis. The metabolites were characterized using 1H and 13C NMR, as well as HRMS, and their purities were confirmed by quantitative NMR to ensure analytical reliability. Validation of the developed analytical method showed that it presented acceptable performance, with linearity >0.99 for all the target analytes, accuracies within ±10 % of nominal concentrations, and intra- and inter-day precisions within 15 %. Application of this method to fillets from fish that had been treated with florfenicol (dose of 10 mg/kg bw daily) demonstrated its effectiveness in consistently detecting FF and its metabolites throughout the treatment. The results emphasized the utility of the method for enhancing pharmacokinetic and residue depletion research. The ability to precisely monitor the drug and its metabolites in treated fish provides important insights into florfenicol metabolism, laying the groundwork for further comprehensive profiling studies of metabolites in fish tissue. [ABSTRACT FROM AUTHOR]

The issue of antimicrobial resistance is becoming an increasingly serious challenge in both human and veterinary medicine. Prudent antimicrobial use in veterinary medicine is warranted and supported by international guidelines, with the Antimicrobial Advice Ad Hoc Expert Group (AMEG) placing particular emphasis on the critically important group B antimicrobials. These antimicrobials are commonly employed, especially in the poultry and swine industry. The impact of florfenicol, a veterinary antibiotic, was studied on the resistance development of Escherichia coli. The aim of the study was to investigate the effect of the use of florfenicol on the development of phenotypic and genomic resistances, not only to the drug itself but also to other drugs. The minimum inhibitory concentrations (MICs) of the antibiotics were investigated at 1×, 10×, 100× and 1000× concentrations using the adapted Microbial Evolution and Growth Arena (MEGA-plate) method. The results demonstrate that florfenicol can select for resistance to fluoroquinolone antibiotics (167× MIC value increase) and cephalosporins (67× MIC value increase). A total of 44 antimicrobial resistance genes were identified, the majority of which were consistent across the samples. Chromosomal point mutations, including alterations in resistance-associated and regulatory genes (acrB, acrR, emrR and robA), are thought to trigger multiple drug efflux pump activations, leading to phenotypically increased resistance. The study underscores the impact of florfenicol and its role in the development of antimicrobial resistance, particularly concerning fluoroquinolone antibiotics and cephalosporins. This study is the first to report florfenicol’s dose-dependent enhancement of other antibiotics’ MICs, linked to mutations in SOS-box genes (mdtABC-tolC, emrAB-tolC and acrAB-tolC) and increased multidrug efflux pump genes. Mutations in the regulatory genes acrR, emrR and rpbA support the possibility of increased gene expression. The results are crucial for understanding antimicrobial resistance and its development, highlighting the promising potential of in vitro evolutionary and coselection studies for future research.

Florfenicol (FLO) has been shown to elicit diverse toxic effects in plants, insects, and mammals. Previously, our investigations revealed that FLO induced abnormal cardiac development and early embryonic mortality in chicken embryos. However, the effect of FLO on mitochondrial responses in stem cells remains unclear. In this study, we show that FLO significantly diminishes proliferation viability and obstructs the directed differentiation of P19 stem cells (P19SCs) into cardiomyocytes. Proteomic analysis revealed 148 differentially expressed proteins in response to FLO. Functional analysis has pinpointed FLO interference with biological processes associated with oxidative phosphorylation within the mitochondria. In alignment with the results of proteomic analysis, we confirmed that FLO inhibits the expression of both nuclear DNA-encoded and mitochondrial DNA-encoded subunits of the electron transport chain. Subsequent experiments demonstrated that FLO disrupts mitochondrial dynamics and induces the mitochondrial unfolded protein response to maintain mitochondrial homeostasis. These findings collectively highlight the significance of mitochondrial dynamics and the mitochondrial unfolded protein response to mediate the decreased proliferation viability and directed differentiation potential in P19SCs treated with FLO. In conclusion, this study provides a comprehensive overview of mitochondrial responses to FLO-induced cytotoxicity and enhances our understandings of the molecular mechanisms underlying FLO-induced embryonic toxicity.

Abstract Background Berberine (BBR) is always used in combination with florfenicol for treating avian in China. Objective This study aims to investigate the effects of BBR on the pharmacokinetics of florfenicol in broilers. Methods Male broilers were randomly divided into the control group and the BBR group (BG). Note that 50 mg/kg BBR or sterile water was orally administrated to broilers. On the 8th day, florfenicol [30 mg/kg body weight (BW)] was orally administered to broilers in both groups. The plasma concentrations of florfenicol were determined by ultra‐high‐performance liquid chromatography (UHPLC). The levels of cytochrome P450 (CYP) 3A37, multidrug resistance 1 (MDR1), and chicken xenobiotic‐sensing orphan nuclear receptor (CXR) mRNA expression in the liver and jejunum were determined by the real‐time PCR. Results The results showed that the Cmax, t1/2z, MRT(0‐∞), and AUC(0‐∞) of florfenicol in BG were significantly increased (by 55.71%, 28.32%, 35.19%, and 55.62%, respectively), while the Tmax and CLz/F of florfenicol were significantly decreased (by 52.13% and 35.82%, respectively). In BG, the levels of CYP3A37, MDR1, and CXR mRNA expression in the liver were significantly decreased to 0.72‐fold, 0.67‐fold, and 0.59‐fold, respectively, and the corresponding mRNA expression in the jejunum were significantly decreased to 0.66‐fold, 0.55‐fold, and 0.64‐fold levels, respectively, relative to their levels in the control group. Conclusions BBR altered the pharmacokinetics of florfenicol, probably related to its inhibition of CYP3A37, MDR1, and CXR mRNA expression in the jejunum and liver.

Abstract The study aimed to examine the effect of simultaneous application of florfenicol and lasalocid on the performance and vital organ function of chickens. For this, 300 chicks were divided into four groups. Group one to three received florfenicol, lasalocid and lasalocid plus florfenicol, respectively. Group four as the control group received a basic diet without lasalocid or florfenicol. Lasalocid was used from 7 to 35 days old, continuously. Florfenicol was used at 21 days old for 5 days. The growth indices were measured at the end of each week. The chickens were euthanized at the ages of 28 and 35 days old after collecting blood samples with and without anticoagulants. The liver, heart, muscle, kidney and sciatic nerve were collected in formalin 10% for histopathological examination. The blood and serum samples were used to determine clinical pathologic and hematologic indices. The ratio of internal organs to body weight and ratio of the right ventricle to the total ventricles (RV/TV) of the heart was measured. Results showed, the use of lasalocid decreased feed conversion rate and triglyceride, and increased total protein. Simultaneous administration of lasalocid and florfenicol affected histopathology of the liver and heart and significantly increased creatine phosphokinase, uric acid and the ratio of RV/TV of heart. The eosinophil percentage in the chickens who received florfenicol plus lasalocid was significantly higher than chickens who received florfenicol alone (p < 0.05). In conclusion, it seems that simultaneous administration of the florfenicol and lasalocid induces side‐effects especially on cardiac function and it is not recommended.

Maternal exposure to antibiotics existing in the environment is a predisposing factor for developmental malformation with metabolic disorders in offspring. In this study, female zebrafish (3 months) were exposed to 0.05 mg/L and 0.5 mg/L florfenicol (FF) for 28 days. After pairing and spawning with healthy male fish, F1 embryos were collected and developed to 5 d post-fertilization (dpf) in clear water. And the adverse effects on the F1 generation were examined thoroughly. The fecundity of F0 female fish and the hatchability, mortality, and body length of F1 larvae significantly decreased in the treatment group. Meanwhile, multi-malformation types were found in the exposure group, including delayed yolk sac absorption, lack of swim bladder, and spinal curvature. Metabolomic and transcriptomic results revealed alterations in metabolism with dysregulation in tricarboxylase acid cycle, amino acid metabolism, and disordered lipid metabolism with elevated levels of glycerophospholipid and sphingolipid. Accompanying these metabolic derangements, decreased levels of ATP and disordered oxidative-redox state were observed. These results were consistent with the damaged mitochondrial membrane potential and respiratory chain function, suggesting that the developmental toxicity and perturbed metabolic signaling in the F1 generation were related to the mitochondrial injury after exposing F0 female zebrafish to FF. Our findings highlighted the potential toxicity of FF to offspring generations even though they were not directly exposed to environmental contaminants.

In two experimental trials; florfenicol pharmacokinetics following a single dose oral administration at 15 mg kg−1 fish body weight and biosafety through extended medicated feeding were studied in the rainbow trout, Oncorhynchus mykiss. The pharmacokinetic trial was conducted for 5 days, whereas the biosafety experiment lasted for a 30-day safety margin followed by a 20-day residual period analysis at 3, 5 and 10 times greater than the therapeutic dose 10 mg kg−1 biomass day−1. Cmax µg kg−1 calculated for florfenicol were found to be 5,360 in intestine, 2,890 in gill, 2,250 in kidney, 973 in liver and 273 in plasma, obtained at Tmax of 16 h. Intestine had utmost area under the concentration–time curve (tissue/plasma) of 13.83 h μg kg−1 and a prolonged half life (t1/2ß) of 28.62 h. The highest apparent metabolic rate value in the kidney (0.327) showed a high level of biotransformation of florfenicol to its metabolite florfenicol amine. The apparent distribution rate of florfenicol amine in muscle, in comparison to the parent drug florfenicol, indicated elimination of the medication mostly in the form of florfenicol amine with t1/2 of 16.75 h. The biosafety of florfenicol orally administered to rainbow trout recorded effective feed consumption, physiological responses, drug tolerance and significantly low drug concentrations in muscle of rainbow trout, thus its usage at 10 mg kg−1 fish body weight is recommended. In the study, the rapid absorption, greater bioavailability, enhanced dispersion, slower elimination and biosafety of the drug form a significant basis for the florfenicol and its metabolite florfenicol amine as a useful antibacterial agent in aquaculture.

Florfenicol (FFC) is a commonly used antibiotic in animal breeding, especially in broiler breeding. Previous studies found that FFC could affect the liver function of chickens. However, the mechanisms underlying the effects of FFC on liver function are still not completely clear. Moreover, the research on drugs that antagonize FFC hepatotoxicity is relatively lacking. Salvia miltiorrhiza polysaccharides (SMPs) have been proved to have obvious liver protection effects. Therefore, we exposed chicks to FFC at the clinically recommended dose of 0.15 g/L. At the same time, 0.15 g/L FFC and 5 g/L SMPs were given to another group of chicks. After 5 days of continuous administration, the livers of chicks from different treatment groups were sequenced by transcriptome and proteome. Based on the analysis of sequencing data, we also focused on the detection of inflammation and oxidation indicators related to the phagosome signaling pathway with significant enrichment of differential factors in the livers of chicks. The results showed that some significantly differentially expressed genes and proteins induced by FFC were enriched in the phagosome signaling pathway, and they increased the expression levels of inflammatory factors and peroxides. However, SMPs intervention significantly reversed the tendency of FFC to alter phagosome signaling pathways and reduced the expression levels of inflammatory factors and peroxides. In conclusion, FFC caused liver inflammation and oxidative stress in chicks by regulating the phagosome signaling pathway. Meanwhile, SMPs could improve the adverse effects of FFC on the phagosome signaling pathway. This study provided new insights into the ameliorative effects and mechanisms of SMPs on hepatotoxicity of FFC.

An immunochromatographic assay (ICA) based on surface-enhanced Raman scattering (SERS) for ultrasensitive and quantitative detection of florfenicol (FF) in food samples was developed. Au nanocubers (AuNCs) with long wavelength absorption were synthesised, characterised and used as the substrate in SERS-ICA. Immunoprobe was prepared by linking Raman reporter and the antibody against FF on AuNCs. The SERS-ICA was completed in 15 min. By measuring the Raman intensities on T lines, quantitative detection of FF was achieved. The IC50 and limit of detection (LOD) of the assay for FF were 0.027 ng mL−1 and 0.12 pg mL−1, respectively. The cross-reactivity (CR) of the assay with thiamphenicol, chloramphenicol and other four drugs were examined. The recoveries of FF in spiked samples were 88.5% ∼ 102.4% with RSD of 2.3% ∼ 7.4%. It was proven that SERS-ICA was able to rapidly detect FF in food samples with high sensitivity, accuracy and precision. [ABSTRACT FROM AUTHOR]

This study aimed to determine the immunity, survival rate, and disease resistance of Litopenaeus vannamei treated using quercetin and florfenicol alone or in combination, after infection with acute hepatopancreatic necrosis syndrome caused by Vibrio parahaemolyticus (VPAHPND). After infection with VPAHPND, different types of feed were given to the shrimp for 5 days, including a control diet (drug-free), florfenicol only diet (15 mg/kg), quercetin only diet (400 mg/kg), a low-dose florfenicol/quercetin combined diet (200 mg/kg quercetin + 7.0 mg/kg florfenicol), a moderate-dose florfenicol/quercetin combined diet (400 mg/kg quercetin + 15 mg/kg florfenicol), and a high-dose florfenicol/quercetin combined diet (800 mg/kg quercetin + 30 mg/kg florfenicol). The cumulative mortality of shrimp was significantly reduced in the drug combination groups compared with either drug used alone (p < 0.05). The density of Vibrio was significantly lower and the immune parameters were significantly increased in the drug combination groups compared with either drug used alone (p < 0.05). Moreover, in the drug combination groups, the hepatopancreas tubules showed better integrity and structure compared with those when either drug was used alone. Therefore, compared with single drug treatment, the florfenicol and quercetin combination enhanced disease resistance, survival, and immune activity of VPAHPND-infected shrimp. When the combination treatment is used, the dosage of florfenicol can be reduced and a better therapeutic effect is obtained. [ABSTRACT FROM AUTHOR]

Copyright of Balikesir Health Sciences Journal / Balıkesir Sağlık Bilimleri Dergisi is the property of Balikesir Health Sciences Journal (BAUN Health Sci J) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the effects of nanocrystallisation technology on the intestinal absorption properties and antibacterial activity of florfenicol (FF). The florfenicol nanocrystals (FF-NC) were prepared by wet grinding and spray drying. Additionally, changes in particle size, charge, morphology, and dissolution of FF-NC in the long-term stability were monitored by laser particle sizer, TEM, SEM, paddle method, and the structure of FF-NC powder was characterised by nuclear magnetic resonance (NMR) test. The antibacterial activity, intestinal absorption and intestinal histocompatibility of FF-NC were investigated by the stiletto, mini broth dilution susceptibility test, in situ single-pass intestinal perfusion (SPIP) and haematoxylin–eosin (H–E) staining. After 12 months of storage, the particle size and zeta potential of FF-NC were 280.43 ± 8.21 nm and −19.64 ± 3.45 mV, and the electron microscopy results showed that FF-NC were nearly circular with no adhesion between particles. In addition, the drug loading, encapsulation efficiency, and dissolution of FF-NC did not change significantly during storage. The inhibition zone of FF-NC against Escherichia coli and Staphylococcus aureus was 21.37 ± 1.70 mm and 25.17 ± 2.47 mm, respectively. Compared with the FF, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of FF-NC are reduced, and the absorption rate constant (Ka) and efficient permeability coefficient (Peff) of FF-NC in the three intestinal segments were increased by 1.28, 0.25, and 9.10 times and 0.59, 0.17, and 6.0 times, respectively. The results of tissue sections showed that FF-NC had little damage to the small intestinal. Nanocrystallisation technology is an effective method to increase the intestinal absorption and antibacterial activity of FF. [ABSTRACT FROM AUTHOR]

Antibiotic resistance genes (ARGs) as a novel type of environmental pollutant pose a health risk to humans. Oxazolidinones are one of the most important antibiotics for the treatment of Gram-positive bacterial infections in humans. Although oxazolidinones are not utilized in the livestock industry, florfenicol is commonly used on farms to treat bacterial infections, which may contribute to the spread of the cfr, optrA, and poxtA genes on farms. Using metagenomics sequencing, we looked into the antibiotic resistome context of florfenicol and oxazolidinone in 10 large-scale commercial farms in China. We identified 490 different resistance genes and 1,515 bacterial genera in the fecal samples obtained from 10 farms. Florfenicol-resistant Kurthia, Escherichia, and Proteus were widely present in these samples. The situation of florfenicol and oxazolidone resistance in pig farms is even more severe. The total number of genes and the abundance of drug resistance genes were higher in pigs than in chickens, including optrA and poxtA. All the samples we collected had a high abundance of fexA and floR. Through nanopore metagenomic analysis of the genetic environment, we found that plasmids, integrative and conjugative element (ICE), and transposons (Tn7-like and Tn558) may play an important role in the spread of floR, cfr, and optrA. Our findings suggest that florfenicol and oxazolidinone resistance genes have diverse genetic environments and are at risk of co-transmission with, for example, tetracycline and aminoglycoside resistance genes. The spread of florfenicol- and oxazolidinone-resistant bacteria on animal farms should be continuously monitored. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study evaluates the effects of a broad-spectrum antibiotic (florfenicol) on antibiotic resistance genes (ARGs) and bacterial community structure in aquatic environments. We constructed an indoor aquatic microcosm model, adding different concentrations of florfenicol (0.1, 1, 10, 100 mg L−1), and water and sediment samples were collected after 0, 7, 30, and 60 days. qPCR and 16S rDNA amplicon sequencing were used to study the changes in the ARGs and bacterial community structure of the collected samples. The results show that the inclusion of florfenicol resulted in an increased abundance of the floR and optrA genes. Adding 100 mg L−1 florfenicol to the water increased the abundance of optrA gene copies with the maximum on the Day 7, and increased the abundance of floR gene copies with the maximum on Day 30. Adding 100 mg L−1 florfenicol to the sediment increased the abundance of floR and optrA genes by one order of magnitude on Day 60. Meanwhile, the average number of operational taxonomic units (OTUs) in the water samples was 257, and the average number of OTUs in sediment samples was 823. The bacterial community diversity and richness in sediments were higher than those in water. The difference between the maximal and minimal values of the Shannon diversity index in the water and sediment samples was 4.36 and 1.95, respectively. The effect of florfenicol on the bacterial community structure in water was much higher than that in sediment. At 30 days, the diversity index and richness index of the florfenicol treatment groups with 1 and 10 mg L−1 concentrations began to increase; at 60 days, the diversity and richness indices of the 100 mg L−1 florfenicol treatment group began to increase. The samples at the same sampling time in the sediments clustered closer together. The results of this study provide a scientific basis for guiding the rational use of florfenicol in aquaculture, maintaining a healthy and stable microecological environment in aquaculture, and provide theoretical data for environmental ecological risk assessment and safety management caused by microbial resistance under the abuse of florfenicol. [ABSTRACT FROM AUTHOR]

The presence of antibiotic residues in the tissue of food animals is a growing concern due to the adverse health effects that they can cause in humans, such as antibiotic resistance bacteria. An inspector-generated sampling (IGS) dataset from the United States National Residue Surveillance Program, collected between 2014 and 2019, was analyzed to investigate the association of changes in the veterinary feed directive (VFD) regulations on the detection of violative penicillin, tetracycline, sulfonamide, desfuroylceftiofur, tilmicosin, and florfenicol, residues in the tissue of food animals. Multivariable logistic regression models were used for analysis. While the animal production class was significantly associated with residue violations for tetracycline, having a sample collection date after the implementation of change in VFD regulations was not. However, the odds of detecting violative sulfonamide and penicillin residues in the tissue of food animals following the implementation of the change in VFD regulations were 36% and 24% lower than those collected before the implementation of the change in VFD regulations period, respectively, irrespective of animal production class. Violative desfuroylceftiofur, tilmicosin, and florfenicol residues in the tissue of food animals were not significantly associated with the implementation of changes in the VFD regulations. Further investigation of the factors that influence the presence of violative antibiotic residues in the tissue of food animals following the change in VFD regulations would lend clarity to this critical issue. [ABSTRACT FROM AUTHOR]

Antimicrobial use in food-producing animals such as pigs is a significant issue due to its association with antimicrobial resistance. Florfenicol is a broad-spectrum phenicol antibiotic used in swine for various indications; however, its effect on the swine microbiome and resistome is largely unknown. This study investigated these effects in piglets treated intramuscularly with florfenicol at 1 and 7 days of age. Fecal samples were collected from treated ( n = 30) and untreated ( n = 30) pigs at nine different time points up until 140 days of age, and the fecal metagenomes were sequenced. The fecal microbiomes of the two groups of piglets were most dissimilar in the immediate period following florfenicol administration. These differences were driven in part by an increase in the relative abundance of Clostridium scindens , Enterococcus faecalis , and Escherichia spp. in the florfenicol-treated piglets and Fusobacterium spp., Pauljensenia hyovaginalis , and Ruminococcus gnavus in the control piglets. In addition to selecting for florfenicol resistance genes ( floR , fexA , and fexB ), florfenicol also selected for genes conferring resistance to the aminoglycosides, beta-lactams, or sulfonamides up until weaning at 21 days of age. Florfenicol-resistant Escherichia coli isolated from these piglets were found to carry a plasmid with floR , along with tet (A), aph(6)-Id , aph(3″)-Ib , sul2 , and bla TEM-1 / bla CMY-2 (phenicols and oxazolidinones) was identified in florfenicol-resistant fexB and poxtA (phenicols and oxazolidinones) was identified in florfenicol-resistant Enterococcus avium isolates from the treated piglets. This study highlights the potential for co-selection and perturbation of the fecal microbial community in pre-weaned piglets administered florfenicol.IMPORTANCEAntimicrobial use remains a serious challenge in food-animal production due to its linkage with antimicrobial resistance. Antimicrobial resistance can reduce the efficacy of veterinary treatment and can potentially be transferred to humans through the food chain or direct contact with animals and their environment. In this study, early-life florfenicol treatment in piglets altered the composition of the fecal microbiome and selected for many unrelated antimicrobial resistance genes up until weaning at 21 days of age. Part of this co-selection process appeared to involve an Enterococcus faecium plasmid carrying a florfenicol resistance gene along with genes conferring resistance to at least four other antimicrobial classes. In addition, florfenicol selected for certain genes that provide resistance to multiple antimicrobial classes, including the oxazolidinones. These results highlight that florfenicol can co-select for multiple antimicrobial resistance genes, and their presence on mobile genetic elements suggests the potential for transfer to other bacteria.E. faecalis isolates from the treated piglets. This study highlights the potential for co-selection and perturbation of the fecal microbial community in pre-weaned piglets administered florfenicol.IMPORTANCEAntimicrobial use remains a serious challenge in food-animal production due to its linkage with antimicrobial resistance. Antimicrobial resistance can reduce the efficacy of veterinary treatment and can potentially be transferred to humans through the food chain or direct contact with animals and their environment. In this study, early-life florfenicol treatment in piglets altered the composition of the fecal microbiome and selected for many unrelated antimicrobial resistance genes up until weaning at 21 days of age. Part of this co-selection process appeared to involve an Escherichia coli plasmid carrying a florfenicol resistance gene along with genes conferring resistance to at least four other antimicrobial classes. In addition, florfenicol selected for certain genes that provide resistance to multiple antimicrobial classes, including the oxazolidinones. These results highlight that florfenicol can co-select for multiple antimicrobial resistance genes, and their presence on mobile genetic elements suggests the potential for transfer to other bacteria.

Florfenicol (FF) is a widely used antimicrobial in veterinary medicine because of its broad antimicrobial activity, although it has certain limitations and raises concerns about the development of antimicrobial resistance genes. These limitations highlight the need to explore novel drug with controlled release systems to enhance the therapeutic efficacy of FF, while minimizing the potential for resistance development. This study introduces an innovative approach for the design, synthesis, and evaluation of lignin-poly(lactic-co-glycolic) acid (PLGA)-FF nanoparticles. By leveraging the properties of PLGA and lignin, this study aimed to augment the solubility, stability, and bioavailability of FF, thereby enabling dosage reduction and consequently diminishing the likelihood of resistance emergence and other limitations. Lignin-PLGA nanoparticles encapsulating FF were synthesized and characterized to assess their physicochemical properties, such as particle size, zeta potential, and drug loading efficiency. The release profile, antimicrobial efficacy, and cytotoxicity were evaluated. Comparative analyses with standard FF formulations were performed to ascertain the superior performance and potential benefits of the nanoparticle-based antimicrobials. Our findings indicate that the synthesized lignin-PLGA nanoparticles exhibited favorable drug delivery attributes, including a controlled and sustained release mechanism, significantly enhanced antimicrobial activity at reduced concentrations relative to free FF, with minimal cytotoxic effects. Importantly, the nanoparticle system inhibited bacterial biofilm formation, which is a key factor in the onset and spread of antimicrobial resistance. These findings underscore the potential of integrating biodegradable polymers with natural compounds to forge innovative pathways in drug delivery, addressing critical challenges in veterinary medicine., Competing Interests: Declarations Competing interests The authors declare no competing interests. Statement of animal ethics Not applicable., (© 2024. The Author(s).)

Zerovalent iron (Fe 0 )-based Fenton-like technology has great potential for treating recalcitrant organic pollutants (ROPs) in wastewater. However, rapidly and precisely manufacturing Fe 0 -based materials with the desired geometries is challenging. Herein, novel three-dimensional printed Fe 0 (3DP-Fe 0 ) and bimetallic 3DP-Ni/Fe 0 were customized by 3D printing for efficient Fenton-like degradation of florfenicol (FLO), a typical antibiotic in wastewater. 3DP-Ni/Fe 0 with hydrogen peroxide (H 2 O 2 ) exhibited superior reactivity toward FLO than 3DP-Fe 0 , generating hydroxyl radicals (·OH) and atomic hydrogen to achieve >90% dehalogenation and >70% total organic carbon removal within 10 min. The resulting degradation intermediates possessed lower antibacterial activity than FLO and did not cause resistance gene proliferation in activated sludge. The Fenton-like activity of 3DP-Ni/Fe 0 was similar across different shapes but increased with increasing porosity and size. Compared with powdered Ni/Fe 0 , 3DP-Ni/Fe 0 exhibited faster electron transfer during Fe(II)/Fe(III) cycling, which increased the utilization efficiency of dissolved Fe 2+ and H 2 O 2 for ·OH production. Moreover, 3DP-Ni/Fe 0 could be reused >150 times, 5-fold more than powdered Ni/Fe 0 , owing to its lower metal ion release and Fe 0 depletion. 3DP-Ni/Fe 0 with H 2 O 2 can also efficiently remove chemical oxygen demand from real wastewater and other ROPs (e.g., acetaminophen, carbamazepine, thiamphenicol, and tetrabromobisphenol A).

Small molecule drugs often exhibit short half-lives, requiring frequent administrations to maintain therapeutic concentrations over an extended period. To address this issue, the fragment crystallizable (Fc) region of IgG, known to prolong the half-life of antibodies via its interaction with the Fc neonatal receptor, was harnessed as a carrier protein to extend the half-life of a small molecule drug, florfenicol. Florfenicol, was chemically coupled to a recombinant Fc protein expressed using the eukaryotic expression system in HEK293 cells. The Fc-florfenicol conjugate exhibited a substantially prolonged half-life of from 3.8 to 9.1 h compared to unconjugated florfenicol and demonstrated excellent therapeutic properties in treating pneumonia in a mouse model. Our results, combined with the literature analysis on Fc-small molecule conjugates, show that Fc can substantially enhance the drug's half-life and suggest the potential for its use as a carrier in novel delivery systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Introduction: Macranthoidin B (MB) is a primary active component of Flos Lonicerae. In Chinese veterinary clinics, Flos Lonicerae is frequently used in combination with florfenicol to prevent and treat infections in livestock and poultry. However, potential interactions between Flos Lonicerae and florfenicol remain unclear. To systematically study these interactions, it is crucial to investigate the individual phytochemicals within Flos Lonicerae . Therefore, MB was selected for this study to assess its effect on the pharmacokinetics of florfenicol in vivo and to explore the underlying mechanisms involved., Methods: Male Sprague-Dawley rats were administered MB (60 mg/kg BW) or sterile water orally for 7 consecutive days. On the 8th day, a single oral dose of florfenicol (25 mg/kg BW) was given. Florfenicol pharmacokinetics were analyzed using ultra-high performance liquid chromatography. The hepatic expression levels of cytochrome P450 (CYP1A2, CYP2C11, CYP3A1), UDP-glucuronosyltransferase (UGT1A1), P-glycoprotein (P-gp), and nuclear receptors, including constitutive androstane receptor (CAR), pregnane X receptor (PXR), and retinoid X receptor alpha (RXRα), were quantified via reverse transcription-quantitative polymerase chain reaction and Western blotting (WB). Hepatic CYP1A2 and CYP2C11 activities were measured using a cocktail method. Additionally, the subcellular expression and localization of CAR, PXR, and RXRαin hepatocytes was assessed using WB and immunofluorescence staining., Results: MB significantly reduces the AUC (0-∞) and MRT (0-∞) of florfenicol. MB also markedly upregulates the mRNA and protein expression of hepatic CYP1A2 and CYP2C11, along with their catalytic activities. Substantial upregulation of CAR and PXR proteins occurs in the hepatocyte nucleus, along with significant nuclear colocalization of the transcriptionally active CAR/RXRα and PXR/RXRαheterodimers, indicating MB-induced nuclear translocation of both CAR and PXR., Discussion: These findings suggest that MB-induced alterations in florfenicol pharmacokinetics, particularly its accelerated elimination, may be due to increased expression and activities of CYP1A2 and CYP2C11, with CAR and PXR potentially involved in these regulatory effects. Further investigation is yet needed to fully elucidate the clinical implications of these interactions concerning the efficacy of florfenicol in veterinary medicine., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Li, Wang, Zhang, Yin, Yang, Li and Liang.)

ABSTRACT: Early use of florfenicol (FFC) can adversely affect the health of broilers. Our previous studies showed that FFC caused kidney injury in broilers. However, the mechanism by which FFC causes nephrotoxicity remains unclear. In order to further explore the regulatory effect of FFC on specific signal pathway in the injured kidneys and the interaction between genes and proteins in this signal pathway, the transcriptome and proteome sequencing were performed on the chick kidneys in the control group and the FFC treatment group. Then, the sequencing data were analyzed, and the screened genes and proteins were verified by real-time quantitative PCR (qPCR) and parallel reaction monitoring (PRM), respectively. The results of sequencing showed that FFC exposure altered significantly the expression levels of 657 genes and 477 proteins in chick kidneys. Among them, 9 significantly differentially expressed genes (including CD28, ICOS, BLB1, BLB2, DMB2, CLDN8, CLDN18, CLDN19, and NEGR1) and 3 significantly differentially expressed proteins (including CD28, ICOS, and CLDN8) were involved in the cell adhesion molecules signaling pathway. Further analysis found that, the changes of the above genes and proteins were related to inflammation and apoptosis of the tissues and histiocytes in chick kidneys. Therefore, the structure and morphology of renal tissues, the expression levels of inflammatory and apoptotic factors, and the apoptotic rate of renal histocytes were detected. It was found that compared with the control group, there was obvious inflammatory cell infiltration in renal tissues of the FFC treatment group. At the same time, the levels of pro-inflammatory factors and pro-apoptotic factors raised significantly, and the apoptotic rate of renal histocytes increased significantly. The above results confirmed that FFC induced inflammatory reaction and apoptosis in chick kidneys by activating the cell adhesion molecules signaling pathway.

The potential health risks associated with simultaneous presence of residues of heavy metals and antibiotics in the environment and food have been of wide concern. However, the adverse health effects of combined heavy metal and antibiotic exposure at low doses remain unclear. In this study, the effects of combined exposure to florfenicol and copper at low doses during early life on toxicity, gut microbiota, drug resistance genes, and the fecal metabolome were investigated in Sprague–Dawley (SD) rats. The results showed that combined exposure induced inflammatory responses and visceral injury as well as faster weight gain compared with florfenicol or copper exposure alone. Alpha and beta diversity indices indicated that the composition of the gut microbiota and the abundance of bacteria related to energy intake and disease in the combined exposure group were significantly altered. The increase in resistance genes (floR, fexA) induced by florfenicol exposure was suppressed under combined exposure to florfenicol and copper. The fecal metabolome also demonstrated that metabolic pathways related to energy intake and liver injury were significantly affected in the combined exposure group. In conclusion, this study shows that combined exposure to florfenicol and copper during early life can pose a nonnegligible health risk even if the exposure concentration of florfenicol or copper is below the safe limit.

Florfenicol is one of the most widely used antibiotics in aquaculture and veterinary clinics because of its low side effects and strong bactericidal effect. A total of 45~60% of florfenicol is not absorbed by the animal body and accumulates in the aquatic environment through a variety of pathways, which affects denitrification. Indoor aquatic microcosm models were constructed and sediment samples were collected at different florfenicol concentrations (0.1, 1, 10, and 100 mg/L) on days 0, 7, 30, and 60 to extract the microbial genome DNA and determine the water properties. qPCR and amplicon sequencing were used to study the dynamic changes in the nirS gene and nirS-type denitrification community structure, diversity, and abundance, respectively. The results showed that high florfenicol stress influenced the sediment’s physicochemical properties, reducing conductivity, alkaline dissolved nitrogen, and organic matter content. In addition, the abundance of nirS, a functional denitrification gene, increased obviously with increased florfenicol concentrations but decreased the diversity of nirS-type denitrification microorganisms. Proteobacteria was the dominant denitrifying phylum in the sediment. Our study provides a scientific basis for the rational use of florfenicol in aquaculture to maintain a healthy and stable microecological environment and also provides a preliminary understanding of the response characteristics of water denitrifying microorganisms to florfenicol exposure.

The plasmid-borne cfr gene, mediating multiple drug resistance (MDR), has been observed in many Gram-positive bacteria. The prevalence of cfr and its co-occurrence with additional antimicrobial resistance (AMR) determinants in Escherichia coli is an ongoing issue. Additionally, the prevalence and transfer mechanism of the cfr gene remain partially investigated. Here, eight cfrpositive E. coli strains were screened using PCR from an extensive collection of E. coli (n = 2,165) strains isolated from pigs and chickens in 2021 in China, with a prevalence rate of 0.37%. All of them were MDR and resistant to florfenicol and tetracycline. These strains can transfer the cfr gene to E. coli J53 by conjugation (1.05 × 10-1 - 1.01 × 10-6). Moreover, the IncX4 plasmid p727A3-62 K-cfr (62,717 bp) harboring cfr in strain EC727A3 was confirmed using Oxford Nanopore Technology. The unknown type plasmid p737A1-27Kcfr (27,742 bp) harboring cfr in strain EC737A1 was also identified. Notably, it was verified by PCR that three of the eight E. coli strains were able to form the cfr-IS26 circular intermediate. It was 2,365 bp in length in strains EC727A3 and ECJHZ21-173, and 2,022 bp in length in EC737A1. Collectively, this study demonstrated that IS26 plays a vital role in transmitting the MDR gene cfr in E. coli via conjugation and provided updated knowledge regarding cfr in E. coli in Eastern China. [ABSTRACT FROM AUTHOR]

The overuse of antibiotics has led to the sharp increase of antibiotic‐resistant bacteria that can consequently transmit and cause hard‐to‐cure human diseases. To deal with this problem, nano drug delivery systems have been widely researched. This report focuses on developing an Alginate/Chitosan‐based nanosystem that carried simultaneously Doxycycline (DOX), Florfenicol (FLO), and silver nanoparticles (AgNPs). The optimal Alginate/Chitosan ratio of 3 : 2 (w/w) created the most stable nanocarrier system. The fabricated DOX‐FLO@AgNPs had a spherical shape with a small size of about 20 nm and could release slowly DOX and FLO at pH of 7.4 and 5.0. In vitro drug release kinetics of DOX and FLO from DOX‐FLO@AgNPs fitted best to the Weibull or Higuchi model by the mechanism of the Fickian or non‐Fickian diffusion. The nanosystem of DOX‐FLO@AgNPs had much lower IC50 of 0.012±0.001 and 0.08±0.005 μg/mL against E.coli and B.subtilis, respectively, than the conventional form. The FIC50 value of smaller than 0.5 μg/mL for 5 out of 6 tested bacteria also indicated the synergistic effect of each component in this antibiotic combination. Moreover, the cytotoxicity assay confirmed the viability of 96.4±2.3 % for vero cell line that exposured to the treatment dose. Therefore, these findings strongly suggest that the DOX‐FLO@AgNPs formulation is promising for combined antibiotic drug delivery and silver nanoparticles, and will be worth investigating for further in vivo potential. [ABSTRACT FROM AUTHOR]

Background: Florfenicol might be ineffective for treating Staphylococcus aureus small colony variants (SCVs) mastitis. Objectives: In this study, florfenicol-loaded chitosan (CS)-sodium tripolyphosphate (TPP) composite nanogels were prepared to allow targeted delivery to SCV infected sites. Methods: The formulation screening, the characteristics, in vitro release, antibacterial activity, therapeutic efficacy, and biosafety of the florfenicol composite nanogels were studied. Results: The optimized formulation was obtained when the CS and TPP were 10 and 5 mg/ mL, respectively. The encapsulation efficiency, loading capacity, size, polydispersity index, and zeta potential of the optimized florfenicol composite nanogels were 87.3% ± 2.7%, 5.8% ± 1.4%, 280.3 ± 1.5 nm, 0.15 ± 0.03, and 36.3 ± 1.4 mv, respectively. Optical and scanning electron microscopy showed that spherical particles with a relatively uniform distribution and drugs might be incorporated in cross-linked polymeric networks. The in vitro release study showed that the florfenicol composite nanogels exhibited a biphasic pattern with the sustained release of 72.2% ± 1.8% at 48 h in pH 5.5 phosphate-buffered saline. The minimal inhibitory concentrations of commercial florfenicol solution and florfenicol composite nanogels against SCVs were 1 and 0.25 µg/mL, respectively. The time-killing curves and live– dead bacterial staining showed that the florfenicol composite nanogels were concentration)dependent. Furthermore, the florfenicol composite nanogels displayed good therapeutic efficacy against SCVs mastitis. Biological safety studies showed that the florfenicol composite nanogels might be a biocompatible preparation because of their non-toxic effects on the renal tissue and liver. Conclusions: Florfenicol composite nanogels might improve the treatment of SCV infections. [ABSTRACT FROM AUTHOR]

Effects and mechanism of carbonyl cyanide chlorophenylhydrazone (CCCP) on antimicrobial activity of florfenicol (FF) and thiamphenicol (TAP) were investigated against amphenicol-resistant Actinobacillus pleuropneumoniae and Pasteurella multocida isolated from diseased swine. Broth microdilution and time-kill assays indicated that CCCP dose-dependently and substantially (4-32 fold MIC reduction) improved amphenicol antimicrobial activity. When combined with CCCP at the lowest literature reported dose (2-5 μg/mL), 85% FF resistant A. pleuropneumoniae and 92% resistant P. multocida showed significantly reduced FF MICs (≥ 4-fold). In contrast, none or few of the susceptible A. pleuropneumoniae and P. multocida had FF MICs reduction ≥ 4-fold. 90% FF resistant A. pleuropneumoniae and 96% resistant P. multocida carried the floR gene, indicating strong association with the FloR efflux pump. With CCCP, the intracellular FF concentration increased by 71% in floR+ resistant A. pleuropneumoniae and 156% in floR+ resistant P. multocida strains but not the susceptible strains. The degree of reduction in TAP MICs was found consistently in parallel to FF for both bacteria. Taken together, partially attributed to blockage of drug-efflux, the combination of FF or TAP with CCCP at sub-cytotoxic concentrations was demonstrated and showed feasibility to combat amphenicol-resistant A. pleuropneumoniae and P. multocida isolated from diseased swine. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We analyzed the proteomic response of the Gram-negative fish pathogen A. salmonicida to iron limitation, an elevated incubation temperature, and the antibiotic florfenicol. Proteins from different subcellular fractions (cytosol, inner membrane, outer membrane, extracellular and outer membrane vesicles) were enriched and analyzed. We identified several iron-regulated proteins that were not reported in the literature for A. salmonicida before. We could also show that hemolysin, an oxidative-stress-resistance chaperone, a putative hemin receptor, an M36 peptidase, and an uncharacterized protein were significantly higher in abundance not only under iron limitation but also with an elevated incubation temperature. This may indicate that these proteins involved in the infection process of A. salmonicida are induced by both factors. The analysis of the outer membrane vesicles (OMVs) with and without applied stresses revealed significant differences in the proteomes. OMVs were smaller and contained more cytoplasmic proteins after antibiotic treatment. After cultivation with low iron availability, several iron-regulated proteins were found in the OMVs, indicating that A. salmonicida OMVs potentially have a function in iron acquisition, as reported for other bacteria. The presence of iron-regulated transporters further indicates that OMVs obtained from 'stressed' bacteria might be suitable vaccine candidates that induce a protective anti-virulence immune response. [ABSTRACT FROM AUTHOR]

In this work, the single-stranded DNA (ssDNA) aptamers specific to florfenicol (FF) and having a high binding affinity were prepared using the magnetic bead-based systematic evolution of ligands by the exponential enrichment technique (MB-SELEX). After 10 rounds of the MB-SELEX screening, aptamers that can simultaneously recognize FF and its metabolite florfenicol amine (FFA) were obtained. The aptamer with the lowest dissociation constant (Kd) was truncated and optimized based on a secondary structure analysis. The optimal aptamer selected was Apt-14t, with a length of 43 nt, and its dissociation constant was 4.66 ± 0.75 nM, which was about 7 times higher than that of the full-length sequence. The potential binding sites and interactions with FF were demonstrated by molecular docking simulations. In addition, a colorimetric strategy for nanogold aptamers was constructed. The linear detection range of this method was 0.00128–500 ng/mL and the actual detection limit was 0.00128 ng/mL. Using this strategy to detect florfenicol in actual milk and eggs samples, the spiked recoveries were 88.9–123.1% and 84.0–112.2%, respectively, and the relative standard deviation was less than 5.6%, showing high accuracy. [ABSTRACT FROM AUTHOR]

Nowadays, plant allelopathy, as a new type of biological algal and/or bacterial inhibition technology, has attracted extensive attention. Eight substances were isolated and identified from Jussiaea stipulacea Ohwi, and five concentration gradients, as well as a control (0, 1.25, 5, 10, 20, and 50 mg/L) were set, with three parallels in each group, and then sampled and detected at 24, 48, 72, and 96 h. When the concentration was 50 mg/L, the inhibition rate of Anabaena was as high as 74.8%, 69.2%, and 70.7% for ursolic acid, kaempferol, and luteolin, respectively. Streptococcus iniae and Aeromonas hydrophila were cultured to a logarithmic phase, and their final concentrations reached 1000, 500, 250, 125, 62.50, 31.25, 15.63, and 7.81 μg/mL. Luteolin and gallic acid showed an inhibitory effect on S iniae and A hydrophila at 1000 μg/mL. We found that allelochemicals also had a certain bacteriostatic effect, among which luteolin has great development potential. [ABSTRACT FROM AUTHOR]

Gut microbiota play a vital role in fish health homeostasis. Antibiotics are known to alter microbial community composition and diversity; however, the substantial effects of antibiotics upon the gut microbiome with respect to immune-related pathways in healthy fish remain unclear. Accordingly, here we explored the impact of two antibiotics on the intestinal health, immune response, microbiome dynamics, and transcriptome profiles of grass carp. A two-week feeding trial was carried out in which the basal diet was complemented with enrofloxacin (10 mg/kg) or florfenicol (10 mg/kg). The results showed that: (1) Enrofloxacin and florfenicol both induced intestinal oxidative stress and reduced the digestive enzyme activity of grass carp. (2) High-throughput sequencing of 16S rDNA revealed that enrofloxacin but not the florfenicol treatment influenced gut microbiota diversity in grass carp by shifting α/β-diversity with more abundant pathogens detected. (3) Transcriptome profiling demonstrated that florfenicol down-regulated the immune-related pathways of grass carp, and the network analysis revealed that IgA was negatively correlated with certain pathogens, such as Shewanella and Aeromonas. (4) Antibiotic-induced alternations of gut core microbes were revealed via immune-related transcripts, as were lower mRNA expression levels of mucosal-related genes. (5) Apoptosis and histopathological changes were detected in the enrofloxacin- and florfenicol-treated groups compared with the control group. Overall, administering antibiotics will promote oxidative stress, cause intestinal flora dysbiosis, inhibit the mucosal immune system, and induce apoptosis in grass carp. [ABSTRACT FROM AUTHOR]

Copyright of Modern Food Science & Technology is the property of Editorial Office of Modern Food Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Florfenicol is an excellent antibiotic and is widely used in animal bacterial diseases. However, its poor water solubility leads to various problems, such as poor absorption and bioavailability. The development of nanocrystals is one of the most useful methods for solubilizing florfenicol, which often requires solubility data of florfenicol in different mixed solvents. In this work, the solubility of florfenicol was determined by the gravimetric method in methanol + water, ethanol + water, 1-propanol + water, and isopropanol + water binary solvents at temperatures from 278.15 to 318.15 K. In these four mixed solvents, the solubility of florfenicol increased with the increase in temperature. The solubility of florfenicol in methanol + water mixed solvent increases with the decrease in water ratio, while the solubility of florfenicol in ethanol + water, 1-propanol + water, or isopropanol + water mixed solvents increased first and then decreased with the decrease in water ratio, indicating a cosolvency phenomenon. The modified Apelblat model, CNIBS/R-K model, Jouyban–Acree model, and NRTL model were used to correlate the solubility data of florfenicol in four binary solvents. RMSD values indicated that the calculated values are in good agreement with the experimental solubility data for all four models, among which the CNIBS/R-K model provides the best correlation. [ABSTRACT FROM AUTHOR]

Florfenicol is widely used for the treatment of bacterial infections in domestic animals. The aim of this study was to analyze the molecular mechanisms of florfenicol and oxazolidinone resistance in Enterococcus isolates from anal feces of domestic animals. The minimum inhibitory concentration (MIC) levels were determined by the agar dilution method. Polymerase chain reaction (PCR) was performed to analyze the distribution of the resistance genes. Whole-genome sequencing and comparative plasmid analysis was conducted to analyze the resistance gene environment. A total of 351 non-duplicated enteric strains were obtained. Among these isolates, 22 Enterococcus isolates, including 19 Enterococcus. faecium and 3 Enterococcus. faecalis, were further studied. 31 florfenicol resistance genes (13 fexA, 3 fexB, 12 optrA, and 3 poxtA genes) were identified in 15 of the 19 E. faecium isolates, and no florfenicol or oxazolidinone resistance genes were identified in 3 E. faecalis isolates. Whole-genome sequencing of E. faecium P47, which had all four florfenicol and oxazolidinone resistance genes and high MIC levels for both florfenicol (256mg/L) and linezolid (8mg/L), revealed that it contained a chromosome and 3 plasmids (pP47-27, pP47-61, and pP47-180). The four florfenicol and oxazolidinone resistance genes were all related to the insertion sequences IS1216 and located on two smaller plasmids. The genes fexB and poxtA encoded in pP47-27, while fexA and optrA encoded in the conjugative plasmid pP47-61. Comparative analysis of homologous plasmids revealed that the sequences with high identities were plasmid sequences from various Enterococcus species except for the Tn6349 sequence from a Staphylococcus aureus chromosome (MH746818.1). The current study revealed that florfenicol and oxazolidinone resistance genes (fexA, fexB, poxtA, and optrA) were widely distributed in Enterococcus isolates from animal in China. The mobile genetic elements, including the insertion sequences and conjugative plasmid, played an important role in the horizontal transfer of florfenicol and oxazolidinone resistance. [ABSTRACT FROM AUTHOR]

Riemerella anatipestifer can cause septicemia and death in ducks and geese, leading to significant economic losses to animal farms. The emergence of resistance of R. anatipestifer to commonly used antibiotics increases the difficulty of treating R. anatipestifer infection. The aim of this study was to evaluate the utility of antibiotic combination to restrict mutant selection of multidrug-resistant (MDR) R. anatipestifer isolates. Pharmacokinetics of florfenicol and chlortetracycline in Pekin ducks were evaluated using both noncompartmental analysis and population pharmacokinetic models. The areas under the curve of florfenicol and chlortetracycline after single 20 and 10 mg/kg oral administration were 49.3 and 6.84 mg*h/L, respectively. Chlortetracycline exhibited high apparent clearance and low systemic exposure. Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) values of the two antibiotics were determined in 10 and 2 MDR R. anatipestifer isolates, respectively, to derive fTMSW (the fraction of time over 24 hours wherein the free drug concentration was within the mutant selection window [MSW]) and fT>MPC (the fraction of time that the free drug concentration was above the MPC). Both fTMSW and fT>MPC were estimated from simulated concentration-time profiles relative to MIC and MPC. Florfenicol and chlortetracycline combination have additive activities against R. anatipestifer in majority of isolates and could significantly decrease monotherapy MPC of florfenicol and chlortetracycline, as well as optimize both fTMSW and fT>MPC parameters, provided that the bioavailability of chlortetracycline is improved. The application of pharmacokinetic/pharmacodynamic analyses to MPC concepts to restrict selection of mutant bacterial strains can help improve short- and long-term outcomes of antibiotic treatment in animal farms. [ABSTRACT FROM AUTHOR]

The overuse or abuse of antimicrobial drugs in aquaculture, aggravates the generation of drug-resistant bacteria, which has caused potential risks to human health and the aquaculture industry. Flavonoid–antibiotic combinations have been shown to suppress the emergence of resistance in bacteria, and sometimes even reverse it. Here, the antibacterial activity of florfenicol in combination with quercetin, a potential drug to reverse multidrug resistance, was tested against Aeromonas hydrophila (A. hydrophila). Of eleven selected antimicrobial agents, quercetin and florfenicol showed the strongest bactericidal effect, and fractional inhibitory concentration (FIC) indices were 0.28, showing a highly synergistic effect. Then, the antibacterial activities of quercetin and florfenicol against A. hydrophila were further tested in vitro and in vivo. Bacterial viability of A. hydrophila decreased in a florfenicol dose-dependent manner, about 16.3–191.4-fold lower in the presence of 15 μg/mL quercetin and 0.156 to 1.25 μg/mL florfenicol than in the absence of quercetin, respectively. The cell killing was maximum at 45 μg/mL quercetin in the dose range tested plus 0.156 μg/mL florfenicol. The viability decreased over time during the combined treatment with quercetin and florfenicol by 60.5- and 115-fold in 0.156 μg/mL florfenicol and 0.625 μg/mL florfenicol, respectively. Additionally, the synergistic effect was confirmed by the bacterial growth curve. Furthermore, quercetin and florfenicol had an obvious synergistic activity in vivo, reducing the bacterial load in the liver, spleen and kidney tissues of Cyprinus carpio up to 610.6-fold compared with the florfenicol group, and improving the survival rate of infected fish from 10% in the control group to 90% in drug combinations group. These findings indicated that quercetin could potentiate the antibacterial activity of florfenicol against A. hydrophila infection and may reduce the use of antimicrobial drugs and improve the prevention and control capability of bacterial resistance. [ABSTRACT FROM AUTHOR]

ABSTRACT: Excessive and nonstandard use of florfenicol (FFC) can damage animal body, pollute ecological environment, and even harm human health. The toxic and side effects of FFC directly affect the production performance of poultry and the safe supply of chicken-related food. Salvia miltiorrhaza polysaccharides (SMPs) are natural macromolecular compounds, and were proved to have the effect of protecting animal liver. We used transcriptome and proteome sequencing technologies to study the effect of FFC on specific signal transduction pathways in chick livers and further explored the regulatory effect of SMPs on the above same signal pathways, and finally revealed the intervention effect and mechanism of SMPs on FFC-induced changes of liver function. The screened sequencing results were verified by qPCR and PRM methods. The results showed that FFC changed significantly 9 genes and 5 proteins in drug metabolism-cytochrome P450 signaling pathway, and the intervention of SMPs adjusted the expression levels of 5 genes and 4 proteins of the above factors. In glycine, serine and threonine metabolism signaling pathway, 8 genes and 8 proteins were significantly changed due to FFC exposure, and SMPs corrected the expression levels of 5 genes and 6 proteins to a certain extent. In conclusion, SMPs alleviated FFC-induced liver metabolic disorder in chicks by regulating the drug and amino acid metabolism pathway. This study is of great significance for promoting the healthy breeding of broilers and ensuring the safe supply of chicken-related products.

Riemerella anatipestifer (RA) is an important pathogen found in poultry. RA infection can kill ducks and lead to significant economic losses. Seven RA strains with different susceptibility phenotypes were chosen to study the pharmacokinetic/pharmacodynamic (PK/PD) integration of florfenicol (FF) alone and in combination with doxycycline (DOX). The checkerboard assay indicated that synergy [fractional inhibitory concentration index (FICI) ≤ 0.5] was detected in the CVCC3952 strain of RA and that additivity (FICI >0.5 to ≤ 1) was observed in other strains. Static time–kill curves showed that the bactericidal effect of FF against RA was produced at a FF concentration ≥4 MIC, and the antibacterial activity of FF against RA was enhanced from the aspects of efficacy and efficacy in combination with DOX. Dynamic time–kill curves indicated that FF elicited bactericidal activity against the CVCC3857 strain with a reduction ≥4.88 log10CFU/ml when the dose was ≥8 mg/L. However, a bactericidal effect was not achieved at the maximum administered dose of FF monotherapy (20 mg/L) for isolates with a MIC ≥4 μg/ml. The effect of FF against RA was enhanced upon combination with DOX. The combination of FF with DOX reduced the bacterial burden ≥4.53 log10CFU/ml for all strains with a MIC ≥4 μg/ml. Data were fitted to a sigmoidal Emax model. The PK/PD parameters of AUC24h/MIC (the area under the concentration–time curve over 24 h divided by the MIC) and %T >MIC (the cumulative percentage of time over a 24-h period at which the concentration exceeded the MIC) of FF for eliciting a reduction of 3 log10CFU/ml was 40.10 h and 58.71, respectively. For strains with a MIC ≤ 16 μg/ml, the magnitude of the AUC24h/MIC and Cmax/MIC required for a 3 log10CFU/ml of bacterial killing was 34.84 h and 4.74 in the presence of DOX at 0.5 MIC, respectively. These data suggest that combination of FF with DOX enhanced the activity against RA strains with various susceptibilities to FF and DOX.

Florfenicol is a broad-spectrum antibiotic commonly prescribed in an extra-label manner for treating meat and dairy goats. Scientific data in support of a milk withdrawal interval recommendation is limited to plasma pharmacokinetic data and minimal milk residue data that is limited to cattle. Therefore, a rapid residue detection test (RRDT) could be a useful resource to determine if milk samples are free of drug residues and acceptable for sale. This study compared a commercially available RRDT (Charm® FLT strips) to detect florfenicol residues in fresh milk samples from healthy adult dairy breed goats treated with florfenicol (40 mg/kg subcutaneously twice 4 days apart) with quantitative analysis of florfenicol concentrations using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). In addition, storage claims for testing bovine milk using the RRDT were assessed using stored goat milk samples. Milk samples were collected every 12 h for a minimum of 26 days. Commercial RRDT strips remained positive in individual goats ranging from 528 to 792 h (22–33 days) after the second dose, whereas, UPLC-MS/MS indicated the last detectable florfenicol concentration in milk samples ranged from 504 to 720 h (21–30 days) after the second dose. Results from stored milk samples from treated goats indicate that samples can be stored for up to 5 days in the refrigerator and 60 days in the freezer after milking prior to being tested with a low risk of false-negative test results due to drug degradation. Elevated somatic cell counts and bacterial colony were noted in some of the milk samples in this study, but further study is required to understand the impact of these quality factors on RRDT results.

Florfenicol was widely used as antibiotic in the livestock and poultry breeding industry, resulting in a serious problem of drug resistance. In order to solve the resistance of florfenicol, this study designed and synthesized a new series of florfenicol-polyarginine conjugates and tested for antimicrobial activities. Drug-sensitive bacteria, gram-negative bacteria Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus), were sensitive to several of the compounds tested. These conjugates also showed excellent activity against drug-resistant strains such as methicillin-resistant S. aureus (MRSA) and florfenicol resistant Escherichia coli strains (2017XJ30, 2019XJ20), one of which as E6 had a minimum inhibitory concentration of 12.5 μmol/L. These conjugates did not allow bacteria to develop resistance and also decreased bacterial growth by membrane depolarization and disruption. Additionally, florfenicol succinate (C1) showed certain activity after coupling with arginine. This suggested that conjugating arginine to florfenicol succinate effectively modulated the properties of prodrugs. These new conjugates may provide useful insights for expanding the pool of antibiotics.

Abstract The pharmacokinetic properties and residue elimination of florfenicol (FLO) and its amine were investigated in European seabass Dicentrarchus labrax at 24°C. The trial mainly included analysis of FLO in plasma after a single dose dietary administration of 10 mg/kg and in muscle plus skin following a multiple dosing (10 mg kg−1 day−1 for 7 days) to estimate pharmacokinetics and residue depletion, respectively. The maximum plasma concentration of FLO was measured to be 1.64 μg/ml, 4 hr post administration. The elimination half‐life (t1/2b) and the area under the concentration‐time curve extrapolated to infinity (AUC0‐∞) were calculated to be 13.0 hr and 34.7 μg h−1 ml−1, respectively. Withdrawal times of FLO and its amine were calculated to be 46.3 degree‐days, indicating a fast removal from the edible tissues of treated European seabass. Overall, FLO can be considered as a potentially efficient antibacterial agent for farmed European seabass provided that additional efforts will be devoted towards its in vitro and clinical efficacy.

The frequent occurrence of antibiotics in the aquatic environment has engendered negative impacts on non-target organisms. The effects of the veterinary antibiotic florfenicol (FLO) during the embryo-larval development of the sea urchin, Paracentrotus lividus was assessed using four increasing concentrations (1, 2, 5 and 10 mg/L). Furthermore, FLO toxicity to adults was investigated through the analysis of oxidative damage, histopathological alterations, lipid metabolism and acetylcholinesterase activity following an exposure period of 96 h. FLO induced embryotoxicity with estimated EC50 values of 5.75, 7.56 and 3.29 mg/L after 12 h, 24 h and 48 h, respectively. It generated oxidative stress assessed as lipid peroxidation in gonads despite the increased antioxidant activity of catalase (CAT). Neurotoxicity was also evident since the AChE activity significantly decreased. Moreover, FLO affected the lipid metabolism by increasing saturated fatty acid (SFA) and monounsaturated fatty acid proportions (MUFA), except in the group exposed to 5 mg/L. The increase in polyunsaturated fatty acid (PUFA) levels and docosahexaenoic acid (DHA, C22:6n-3) proportions were noted with all FLO concentrations. Eicosapentaenoic acid (EPA, C20:5n-3) decreased, while arachidonic acid (ARA, C20:4n-6) increased in sea urchins exposed to 5 and 10 mg/L FLO. Histopathological alterations of gonadal tissues represent an additional confirmation about the toxicity of this antibiotic that might decrease the reproductive performance of this species. Nevertheless, even if reproduction of sea urchins would be partially successful, the embryotoxicity would compromise the normal development of the embryos with consequences on the population. [Display omitted] • FLO effects were assessed for the first time in sea urchin. • FLO induced oxidative and neurotoxicity in gonads sea urchin. • FLO affected the lipid metabolism and induced histopathological alterations. • FLO induced embryotoxicity in sea urchin. • FLO affects the reproduction and the development of sea urchin. [ABSTRACT FROM AUTHOR]