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Antibiotics have been widely used in the aquatic industry. Enrofloxacin, florfenicol and sulfamethoxazole are three typical antibiotic types of fluoroquinolone, chloramphenicol and sulfamethoxazole. Their safety reference values in aqua-culture and ecological risks in natural waters have not been clear. In this study, species sensitivity distribution (SSD) was used to determine the biological reference value of typical antibiotics for freshwater aquaculture, and SSD forward method and risk entropy value were used to evaluate the ecological risk of three antibiotics in natural rivers. The results showed that the safety reference values of enrofloxacin, florfenicol and sulfamethoxazole were 58 μg/L, 267 μg/L and 42 μg/L. Potentially affected fraction and risk entropy indicate that there is no ecological risk for the three antibiotics in natural waters. This study provides scientific basis and theoretical guidance for the scientific use of antibiotics in aquatic industry and systematic evaluation of ecological risk of antibiotics in waters. [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. [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.)

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 FROM AUTHOR]

Extensively employed antibiotics in livestock cause residue in food products that would threaten public health safety. In this work, we have developed a flexible, sensitive, cost-effective graphene oxide (GO)/silver–polyester fibrous membrane (PFM) flexible SERS substrate (GO–Ag–PFM) which is suitable for in situ food safety detection. PFMs built nanoporous networks as a flexible template, while GO–Ag nanomaterials were precipitated on the crossed fibers by self-assembly techniques, providing a density "hot-spot" that significantly increased electromagnetic fields. The lowest distinguishable level of rhodamine 6G is 10−9 mol/L, and the flexible SERS substrates also exhibit good uniformity and reproducibility. The sensitive GO–Ag–PFM flexible SERS substrates achieve low-level SERS detection of florfenicol (FF). The estimated LOD is low to 2.46 × 10−9 mol/L for FF. The proposed method can be applied to the determination of FF residues in milk. The recoveries were 89–98% with a relative standard deviation of 4.5–9.1%, which is expected to show great potential in food safety testing. [ABSTRACT FROM AUTHOR]

The study aimed to examine the chronic toxicity effects of oxytetracycline (OTC) and florfenicol (FLO) antibiotics, commonly used in shrimp farms, on the growth performance, chlorophyll a content, and total protein of Chaetoceros muelleri microalgae. C. muelleri, initially at a density of 4,000 cells per milliliter, underwent exposure to oxytetracycline at doses of 7.43 milligrams per liter and florfenicol at 5.20 milligrams per liter for 12 days. Subsequent assessments focused on growth metrics, chlorophyll a content, and total protein. The findings highlighted a significant reduction in the growth, chlorophyll a content, and protein synthesis of C. muelleri following exposure to both OTC and FLO antibiotics (p < 0.05). Moreover, the study revealed that FLO exhibited higher toxicity toward C. muelleri compared to OTC. The observed decline in growth, chlorophyll a content, and protein synthesis in C. muelleri under OTC and FLO exposure could be attributed to the inhibitory impact of these antibiotics on cellular respiration and protein synthesis pathways.

Abstract The objective of this study was to synthesize and characterize pharmaceutical characteristics of florfenicol sustained-release granules (FSRGs) in vitro and in vivo. FSRGs were synthesized using monostearate, polyethylene glycol 4000 and starch. In vitro dissolution profiles were studied using the rotating basket method in pH 1.2 HCl solution and pH 4.3 acetate buffer. Twenty-four male healthy Landrace×Yorkshire pigs were equally divided into three groups and administered a 20 mg/kg i.v bolus of florfenicol solution and dosed orally with FSRGs in the fasting and fed states. The Higuchi model was the best fit for the drug release profile in pH 1.2 and pH 4.3 media, and the mechanism of drug dissolution was governed by both diffusion and dissolution. We established a level A in vitro - in vivo correlation for FSRGs and the in vivo profile of the FSRGs can be estimated by the in vitro drug release.

Florfenicol (FF) is a broad-spectrum antibiotic used to treat gastrointestinal and respiratory infections in domestic animals. Considering FF’s rapid elimination via urine after drug treatment, its use increases concerns about environmental contamination. The objective of the study was to establish a sustainable chromatographic method for simple analysis of FF in pig urine to investigate the urinary excretion of FF after a single intramuscular administration of 20 mg FF/kg body weight. The urine sample was prepared using a centrifuge and regenerated cellulose filter, and the diluted sample was analyzed. The method was validated in terms of linearity, the limit of detection (0.005 µg/mL) and quantitation (0.016 µg/mL), repeatability and matrix effect (%RSD ranged up to 2.5), accuracy (varied between 98% and 102%), and stability. The concentration-time profile of pig urine samples collected within 48 h post-drug administration showed that 63% of FF’s dose was excreted. The developed method and previously published methods used to qualify FF in the urine of animal origin were evaluated by the National Environmental Method Index (NEMI), Green Analytical Procedure Index (GAPI) and Analytical GREENness Metric Approach (AGREE). The greenness profiles of published methods revealed problems with high solvents and energy consumption, while the established method was shown to be more environmentally friendly.

The accumulation of antibiotics in the aquatic environment is increasingly becoming a risk to the health of aquatic animal. The purpose of this study was to investigate the acute and chronic toxicity of florfenicol (FF) to zebrafish. A 56-day chronic toxicity test followed a 96-h acute toxicity test. The chronic toxicity test was divided into five FF concentration groups: 0 mg/L (C), 5 mg/L (T5), 10 mg/L (T10), 20 mg/L (T20) and 40 mg/L (T40). Each group had five replicates, with 20 Zebrafish per replicate. The acute toxicity test results showed that the 96 h-LC50 of FF was greater than 2000 mg/L, indicating low toxicity. The exposure concentrations of FF exceeding 20 mg/L can cause oxidative damage to the liver and gill tissues of fish, leading to the accumulation of oxidative products in the tissues and severe damage to antioxidant capacity. The reactive oxygen species (ROS) generated by severe oxidative stress activates the toll like receptors (TLR) pathway, inducing inflammation in the liver and gill tissues, stimulating the upregulation of inflammatory factor expression levels, and leading to immune system disorders. FF exposure at a concentration of 5 mg/L can lead to a significant decrease in the diversity and evenness of gut microbiota. The concentration of FF in water bodies above 37.52 mg/L poses a potential risk to aquatic products.

The study aimed to examine the chronic toxicity effects of oxytetracycline (OTC) and florfenicol (FLO) antibiotics, commonly used in shrimp farms, on the growth performance, chlorophyll a content, and total protein of Chaetoceros muelleri microalgae. C. muelleri, initially at a density of 4,000 cells per milliliter, underwent exposure to oxytetracycline at doses of 7.43 milligrams per liter and florfenicol at 5.20 milligrams per liter for 12 days. Subsequent assessments focused on growth metrics, chlorophyll a content, and total protein. The findings highlighted a significant reduction in the growth, chlorophyll a content, and protein synthesis of C. muelleri following exposure to both OTC and FLO antibiotics (p < 0.05). Moreover, the study revealed that FLO exhibited higher toxicity toward C. muelleri compared to OTC. The observed decline in growth, chlorophyll a content, and protein synthesis in C. muelleri under OTC and FLO exposure could be attributed to the inhibitory impact of these antibiotics on cellular respiration and protein synthesis pathways. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Doxycycline hydrochloride and florfenicol combination (DoxHcl&FF) is an effective treatment for respiratory diseases. In the study, our objective was to evaluate the activity of DoxHcl&FF against Actinobacillus pleuropneumoniae (APP) in porcine pulmonary epithelial lining fluid (PELF) and the optimal dosage scheme to avoid the development of resistance. The DoxHcl&FF was administered intramuscularly (IM) at 20 mg/kg, and the PELF was collected at different time points. The minimum inhibitory concentration (MIC) and time-mortality curves were also included in the study. Based on the sigmoid Emax equation and dose equations, the study integrated the in vivo pharmacokinetic data of infected pigs and ex vivo pharmacodynamic data to obtain the area under concentration time curve (AUC0-24h)/MIC values in PELF and achieve bacteriostatic activity, bactericidal activity and the virtual eradication of bacteria. The study showed that the combination of DoxHcl and FF caused no significant changes in PK parameters. The peak concentration (Cmax) of FF in healthy and diseased pigs was 8.87 ± 0.08 μg/mL and 8.67 ± 0.07 μg/mL, the AUC0-24h were 172.75 ± 2.52 h·μg/mL and 180.22 ± 3.13 h·μg/mL, the Cmax of DoxHcl was 7.91 ± 0.09 μg/mL and 7.99 ± 0.05 μg/mL, and the AUC0-24h was 129.96 ± 3.70 h·μg/mL and 169.82 ± 4.38 h·μg/mL. DoxHcl&FF showed strong concentration-dependent tendencies. The bacteriostatic, bactericidal, and elimination activity were calculated as 5.61, 18.83 and 32.68 h, and the doses were 1.37 (bacteriostatic), 4.59 (bactericidal) and 7.99 (elimination) mg/kg. These findings indicated that the calculated recommended dose could assist in achieving more precise administration, increasing the effectiveness of DoxHcl&FF treatment for APP infections.

Abstract Background Avian pathogenic Escherichia coli (APEC) are considered a growing health problem to both poultry and the public, particularly due to its multi-drug resistance. Zinc oxide nanoparticles (ZnO-NPs) are a promising multi-benefit candidate. This study focused on boosting the antimicrobial effect of the chemically synthesized ZnO-NPs using Polyethylene glycol-6000 (PEG-6000) and evaluating their potential to recover the sensitivity of Florfenicol and Streptomycin-resistant APEC to these drugs in a concentration range of 0.1–0.4 mg/mL. Four samples of ZnO-NPs were formulated and tested microbiologically. Results The physicochemical characterization showed well-crystallized spherical in situ synthesized ZnO-NPs using PEG-6000 (surfactant) and ethanol (co-surfactant) of ∼19–67 nm particle size after coating with PEG-6000 molecules. These ZnO-NPs demonstrated a strong concentration-dependent antibacterial effect against multidrug-resistant APEC strains, with a minimum inhibitory concentration of 0.1 mg/mL, Combining PEG-6000 coated in situ synthesized ZnO-NPs and Florfenicol induced 60% high sensitivity (30 mm inhibitory-zone), 30% intermediate sensitivity, and 10% resistance against APEC strains. The combination with Streptomycin revealed 50% high sensitivity, 30% intermediate sensitivity, and 20% resistance with a 20 mm maximum zone of inhibition using agar well diffusion test. Conclusion In situ preparation of ZnO-NPs using PEG-6000 and ethanol followed by coating with PEG-6000 enhanced its antibacterial activity in minimum inhibitory concentration and regained the efficacy of Florfenicol and Streptomycin against APEC, referring to a non-antibiotic antimicrobial alternative and an effective combination regimen against multidrug-resistant APEC E. coli in veterinary medicine.

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.

The objective of this study was to synthesize and characterize pharmaceutical characteristics of florfenicol sustained-release granules (FSRGs) in vitro and in vivo. FSRGs were synthesized using monostearate, polyethylene glycol 4000 and starch. In vitro dissolution profiles were studied using the rotating basket method in pH 1.2 HCl solution and pH 4.3 acetate buffer. Twenty-four male healthy Landrace×Yorkshire pigs were equally divided into three groups and administered a 20 mg/kg i.v bolus of florfenicol solution and dosed orally with FSRGs in the fasting and fed states. The Higuchi model was the best fit for the drug release profile in pH 1.2 and pH 4.3 media, and the mechanism of drug dissolution was governed by both diffusion and dissolution. We established a level A in vitro - in vivo correlation for FSRGs and the in vivo profile of the FSRGs can be estimated by the in vitro drug release. [ABSTRACT FROM AUTHOR]

Background: Linezolid is a critically important oxazolidinone antibiotic used in human medicine. Although linezolid is not licensed for use in food-producing animals, the use of florfenicol in veterinary medicine co-selects for oxazolidinone resistance genes. Objective: This study aimed to assess the occurrence of cfr, optrA, and poxtA in florfenicol-resistant isolates from beef cattle and veal calves from different herds in Switzerland. Methods: A total of 618 cecal samples taken from beef cattle and veal calves at slaughter originating from 199 herds were cultured after an enrichment step on a selective medium containing 10 mg/L florfenicol. Isolates were screened by PCR for cfr, optrA, and poxtA which are genes known to confer resistance to oxazolidinones and phenicols. One isolate per PCR-positive species and herd was selected for antimicrobial susceptibility testing (AST) and whole-genome sequencing (WGS). Results: Overall, 105 florfenicol-resistant isolates were obtained from 99 (16%) of the samples, corresponding to 4% of the beef cattle herds and 24% of the veal calf herds. Screening by PCR revealed the presence of optrA in 95 (90%) and poxtA in 22 (21%) of the isolates. None of the isolates contained cfr. Isolates included for AST and WGS analysis were Enterococcus (E.) faecalis (n = 14), E. faecium (n = 12), E. dispar (n = 1), E. durans (n = 2), E. gallinarum (n = 1), Vagococcus (V.) lutrae (n = 2), Aerococcus (A.) urinaeequi (n = 1), and Companilactobacillus (C.) farciminis (n=1). Thirteen isolates exhibited phenotypic linezolid resistance. Three novel OptrA variants were identified. Multilocus sequence typing identified four E. faecium ST18 belonging to hospital-associated clade A1. There was a difference in the replicon profile among optrA- and poxtA-harboring plasmids, with rep9 (RepA_N) plasmids dominating in optrA-harboring E. faecalis and rep2 (Inc18) and rep29 (Rep_3) plasmids in poxtA-carrying E. faecium. Conclusion: Beef cattle and veal calves are reservoirs for enterococci with acquired linezolid resistance genes optrA and poxtA. The presence of E. faecium ST18 highlights the zoonotic potential of some bovine isolates. The dispersal of clinically relevant oxazolidinone resistance genes throughout a wide variety of species including Enterococcus spp., V. lutrae, A. urinaeequi, and the probiotic C. farciminis in food-producing animals is a public health concern. [ABSTRACT FROM AUTHOR]

Florfenicol has a significant therapeutic effect on animal bacterial diseases, most of metabolites enter the soil in the form of metabolites in feces or urine and pollute environment. Soil ecological model was established by experiment to investigate the effects of florfenicol residues in soil on 16S rDNA sequence diversity of phosphorus-solubilizing bacteria. Five different concentrations of florfenicol (0 mg·kg-1, 0.1 mg·kg-1, 1 mg·kg-1, 10 mg·kg-1 and 100 mg·kg-1) were used to collect soil samples on the 7 d, 21 d and 49 d after dosing. The effects of florfenicol on 16S rDNA sequence diversity of soil phosphorus-solubilizing bacteria were determined by amplifed ribosomal DNA restriction analysis (ARDRA) and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) method. The results showed that the number of Operational Taxonomic Units (OTUs) types decreased with the increase of florfenicol concentration, and the percentage of OTUs number to bacteria were the lowest at 100 mg·kg-1 florfenicol concentration after 21d treating, which was 8.33%. The phosphorus-solubilizing bacteria were amplified by ERIC-PCR after 21d treating, the fingerprint type of ERIC-PCR decreased with the increase of drug concentration, and the diversity index of the drug group was significantly lower than that of the blank control group. This indicated that florfenicol had an effect on the dominance, richness and evenness of soil phosphorus-solubilizing bacteria community. [ABSTRACT FROM AUTHOR]

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Simple Summary: Florfenicol is a bacteriostatic antibiotic that is primarily used in veterinary medicine to treat a range of diseases in farm and aquatic animals. This synthetic analog of thiamphenicol and chloramphenicol works by inhibiting ribosomal activity, thereby disrupting bacterial protein synthesis, and has been proven in its effectiveness against a variety of Gram-positive and Gram-negative bacterial groups. Additionally, florfenicol has been found to possess anti-inflammatory properties and reduce immune cell proliferation and cytokine production. However, the inappropriate use of florfenicol has led to concerns about resistance genes, and its low solubility in water has made it difficult to formulate aqueous solutions using organic solvents. This review aims to synthesize the various applications of florfenicol in veterinary medicine, explore the potential use of nanotechnology to improve its effectiveness and analyze the advantages and limitations of such approaches. This review draws on data from scientific articles and systematic reviews found in multiple databases. Florfenicol is a broad-spectrum bacteriostatic antibiotic used exclusively in veterinary medicine in order to treat the pathology of farm and aquatic animals. It is a synthetic fluorinated analog of thiamphenicol and chloramphenicol that functions by inhibiting ribosomal activity, which disrupts bacterial protein synthesis and has shown over time a strong activity against Gram-positive and negative bacterial groups. Florfenicol was also reported to have anti-inflammatory activity through a marked reduction in immune cell proliferation and cytokine production. The need for improvement came from (1) the inappropriate use (to an important extent) of this antimicrobial, which led to serious concerns about florfenicol-related resistance genes, and (2) the fact that this antibiotic has a low water solubility making it difficult to formulate an aqueous solution in organic solvents, and applicable for different routes of administration. This review aims to synthesize the various applications of florfenicol in veterinary medicine, explore the potential use of nanotechnology to improve its effectiveness and analyze the advantages and limitations of such approaches. The review is based on data from scientific articles and systematic reviews identified in several databases. [ABSTRACT FROM AUTHOR]

Florfenicol is commonly used to treat bacterial diseases in striped catfish Pangasianodon hypophthalmus aquaculture with limited knowledge of pharmacokinetic database, explaining treatment failures experienced by farmers. Striped catfish (100 g) were fed medicated feed (10 mg florfenicol/kg fish) by oral gavage. Plasma, liver, and kidney were collected up to 96.0 h after drug administration and analyzed for florfenicol. A single oral gavage dose of 10 mg florfenicol/kg fish revealed a rapid elimination, demonstrated by an elimination half-life (T1/2el) of 2.56 h. Florfenicol amine was found in liver and kidney tissue. The calculation of T > MIC (time that the concentration remains above the minimum inhibitory concentration) revealed a potential therapeutic effect on bacillary necrosis, a common disease in striped catfish if the dosing interval is 12 h. The depletion of florfenicol in striped catfish muscle was determined in feeding trials with medicated feed containing florfenicol at 10 mg/kg fish for five consecutive days in tank and pond conditions. The fast elimination of florfenicol resulted in a withdrawal time of two days (or 39 degree days) in proposed tank-rearing conditions and four days (or 112 degree days) in pond-rearing conditions. [ABSTRACT FROM AUTHOR]

This work aimed to assess the effects of the coadministration of pentoxifylline (PTX) on the pharmacokinetic profile of florfenicol (FFC) after intramuscular administration in rabbits. Ten New Zealand white rabbits, 1 year of age and 3.9 ± 0.1 kg body weight, were assigned according to a randomized block design to Group 1 (FFC): treated with 30 mg/kg of FFC intramuscularly, and Group 2 (PTX + FFC) treated with an oral dose of 30 mg/kg PTX 45 min before the intramuscular injection of 30 mg/kg FFC. Blood samples were collected before and at different times between 0.5 and 12.0 h after drug administration. FFC plasma concentrations were determined by high‐performance liquid chromatography. Results showed that IM injection of the long‐acting formulation of FFC in rabbits resulted in a slow increase in mean plasma concentrations reaching a Cmax of 3.09 ± 0.52 ug/mL at 2.8 ± 0.45 h (Tmax) after drug administration. While coadministration of PTX and FFC decreased the time to achieve the maximal concentration by modifying the absorption of FFC without changes in the other pharmacokinetic parameters. [ABSTRACT FROM AUTHOR]

Florfenicol was administered to five heifers intramuscularly at a dose rate of 20 mg/kg bwt and following wash‐out period, subcutaneously at a dose rate of 40 mg/kg bwt. Blood plasma samples were collected from heifers before injection of florfenicol and up to 120 h after intramuscular (IM) injection and up to 264 h after subcutaneous (SC) injection. Florfenicol concentrations in plasma were measured by high‐performance liquid chromatography with mass‐spectrometric detection. Pharmacokinetics of florfenicol was estimated using non‐compartment analysis. Mean maximum plasma concentration, area under the concentration–time curve and elimination half‐life for florfenicol were 3.2 μg/ml, 101.5 μg × h/ml and 24.5 h, respectively, after IM injection at 20 mg/kg bwt, and 2.7 μg/ml, 194.5 μg × h/ml and 103.8 h, respectively, after SC injection at 40 mg/kg bwt. The obtained results indicated that both administration routes provided comparable bioavailability, whereas SC route was attributed with lower peak levels and markedly slower absorption of florfenicol from injection site. Both administration routes provided plasma florfenicol levels which are expected to be effective against prevalent infectious agents of cattle. [ABSTRACT FROM AUTHOR]

Belamcanda chinensis (L.) DC, commonly used with florfenicol in Chinese veterinary clinics for respiratory tract infections, contains the major effective isoflavone, tectoridin (TEC). This study aimed to investigate the impact of TEC co-administration on the pharmacokinetics of florfenicol in vivo. Male rats received oral TEC (50 mg/kg BW) or sterile water for seven days, followed by a single oral dose of florfenicol (25 mg/kg BW) on the 8th day. Non-compartmental methods analysed the pharmacokinetics of florfenicol, while real-time reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunohistochemical analyses measured expression levels of cytochrome P450 (CYP) isoforms in the liver and P-glycoprotein (P-gp) in the jejunum. TEC significantly decreased florfenicol's AUC(0–∞), MRT(0–∞), t1/2z, Vz/F, and Cmax by 24.75%, 18.43%, 55.47%, 43.05%, and 19.48%, while increasing CLz/F by 33.33%. TEC also up-regulated hepatic CYP1A2 and CYP3A1 mRNA expression, as well as intestinal MDR1, by 1.39-fold, 1.85-fold, and 1.65-fold. This coincided with a respective increase in protein expression by 1.37-fold, 1.39-fold, and 1.43-fold. These findings suggest that TEC-induced alterations in the pharmacokinetics of florfenicol may be attributed to increased CYP and P-gp expression. Further investigations are warranted to understand the implications of these findings on the clinical effectiveness of florfenicol in veterinary practice. [ABSTRACT FROM AUTHOR]

Copyright of Veterinarska Stanica is the property of Croatian Veterinary Institute 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.)

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui 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 was designed to evaluate the Ameliorative effect of N-acetylcysteine (NAC) against possible florfenicol (FFC)-induced intestinal injuries in broiler chicks. A total of 120 broiler chicks were allocated into 4 equal groups. Group (1) was kept as a control, while group (2) administered with NAC (100 mg ̸L of drinking water) for 5 days from 15 to 20 days of age. Group (3) was administered with toxic dose of FFC (60mg ̸kg B.Wt.) orally for 5 days from 18 to 22 days of age. Group (4) was co-administered with NAC with FFC with the same previous doses during the same treatment periods. The histopathological examination was performed to evaluate NAC-ameliorative effects. Results ensure that FFC induced intestinal injuries in broilers and NAC can ameliorate such deleterious effects which reflected by an enhancement histopathological finding. [ABSTRACT FROM AUTHOR]

The present study was designed to evaluate the pretreatment protectant effect of Betaine against possible deleterious effects of florfenicol (FFC) in broiler chicks. A total of 120 broiler chicks were allocated into 4 groups (each of 30 chicks). Group one was kept as a control, while group two was administered with betaine (40mg/kg b.wt. orally from 16 to 20 days of age). Group three was administered with toxic dose of FFC (60 mg/ kg b.wt. orally from 18 to 22 days of age). Group four was co-administered with Betaine with FFC by the same previous doses on the same treatment periods. The biochemical analysis of hepatic and renal indices and histopathological examination were performed to evaluate the protectant effects of betaine on possible FFC-induced hepatorenal toxicity. Results emphasized that large dose of FFC induced hepatorenal toxicity in broilers and pre-treatment with betaine mitigates FFC-adverse effects by enhancement of hepatorenal indices and histopathological pictures of those organs. [ABSTRACT FROM AUTHOR]

Background: Experimental reports have demonstrated that florfenicol (FFC) exerts potent anti-inflammatory effects, improving survival in a murine endotoxemia model. Considering the anti-inflammatory and immunomodulatory properties of pentoxifylline (PTX) as an adjuvant to enhance the efficacy of antibiotics, the anti-inflammatory effects of the interaction FFC/PTX over the E. coli Lipopolysaccharide (LPS)-induced acute inflammatory response was evaluated in rabbits. Methods: Twenty-five clinically healthy New Zealand rabbits (3.8 ± 0.2 kg body weight: bw), were distributed into five experimental groups. Group 1 (control): treated with 1 mL/4 kg bw of 0.9% saline solution (SS) intravenously (IV). Group 2 (LPS): treated with an IV dose of 5 µg/kg of LPS. Group 3 (pentoxifylline (PTX) + LPS): treated with an oral dose of 30 mg/kg PTX, followed by an IV dose of 5 µg/kg of LPS 45 min after PTX. Group 4 (Florfenicol (FFC) + LPS): treated with an IM dose of 20 mg/kg of FFC, followed by an IV dose of 5 µg/kg of LPS 45 min after FFC administration. Group 5 (PTX + FFC + LPS): treated with an oral dose of 30 mg/kg of PTX, followed by an IM dose of 20 mg/kg of FFC, and, 45 min after an IV dose of 5 µg/kg of LPS was administered. The anti-inflammatory response was evaluated through changes in plasma levels of interleukins (TNF-α, IL-1β and IL-6), C-reactive protein (CRP), and body temperature. Results: It has been shown that each drug produced a partial inhibition over the LPS-induced increase in TNF-α, IL-1β, and CRP. When both drugs were co-administered, a synergistic inhibitory effect on the IL-1β and CRP plasma concentrations was observed, associated with a synergic antipyretic effect. However, the co-administration of PTX/FFC failed to modify the LPS-induced increase in the TNF-α plasma concentrations. Conclusions: We concluded that the combination of FFC and PTX in our LPS sepsis models demonstrates immunomodulatory effects. An apparent synergistic effect was observed for the IL-1β inhibition, which peaks at three hours and then decreases. At the same time, each drug alone was superior in reducing TNF-α levels, while the combination was inferior. However, the peak of TNF-α in this sepsis model was at 12 h. Therefore, in rabbits plasma IL-1β and TNF-α could be regulated independently, thus, further research is needed to explore the effects of this combination over a more prolonged period. [ABSTRACT FROM AUTHOR]

A major problem of our time is the ever-increasing resistance to antimicrobial agents in bacterial populations. One of the most effective ways to prevent these problems is to target antibacterial therapies for specific diseases. In this study, we investigated the in vitro effectiveness of florfenicol against S. suis, which can cause severe arthritis and septicemia in swine herds. The pharmacokinetic and pharmacodynamic properties of florfenicol in porcine plasma and synovial fluid were determined. After a single intramuscular administration of florfenicol at 30 mg/kgbw, the AUC0–∞ was 164.45 ± 34.18 µg/mL × h and the maximum plasma concentration was 8.15 ± 3.11 µg/mL, which was reached in 1.40 ± 0.66 h, whereas, in the synovial fluid, these values were 64.57 ± 30.37 µg/mL × h, 4.51 ± 1.16 µg/mL and 1.75 ± 1.16 h, respectively. Based on the MIC values of the 73 S. suis isolates tested, the MIC50 and MIC90 values were 2 µg/mL and 8 µg/mL, respectively. We successfully implemented a killing–time curve in pig synovial fluid as a matrix. Based on our findings, the PK/PD breakpoints of the bacteriostatic (E = 0), bactericidal (E = −3) and eradication (E = −4) effects of florfenicol were determined and MIC thresholds were calculated, which are the guiding indicators for the treatment of these diseases. The AUC24h/MIC values for bacteriostatic, bactericidal and eradication effects were 22.22 h, 76.88 h and 141.74 h, respectively, in synovial fluid, and 22.42 h, 86.49 h and 161.76 h, respectively, in plasma. The critical MIC values of florfenicol against S. suis regarding bacteriostatic, bactericidal and eradication effects in pig synovial fluid were 2.91 ± 1.37 µg/mL, 0.84 ± 0.39 µg/mL and 0.46 ± 0.21 µg/mL, respectively. These values provide a basis for further studies on the use of florfenicol. Furthermore, our research highlights the importance of investigating the pharmacokinetic properties of antibacterial agents at the site of infection and the pharmacodynamic properties of these agents against different bacteria in different media. [ABSTRACT FROM AUTHOR]

Florfenicol is used worldwide for its low side effects and strong bactericidal effect. Florfenicol is physicochemically stable and can persist in natural water bodies and affect water denitrification. Indoor aquatic microcosm models were constructed and water 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 of nirS gene and nirS-type denitrifying communities structure, diversity and abundance, respectively. The results showed that higher florfenicol concentrations caused accumulation of nitrate and ammonium nitrogen in water. Florfenicol stress caused orders of magnitude changes in nirS gene abundance, showing a trend of increasing first and then decreasing. 100 mg/L florfenicol addition led to a sustained increase of nirS gene abundance in water bodies. The florfenicol addition altered denitrifying community structure and suppressed the richness and diversity index of denitrifying bacteria in water body. Over time, the richness and diversity index gradually recovered. Proteobacteria was always the dominant denitrifying phylum in water. The relative abundance of Pseudomonas and beta proteobacterium showed obvious positive correlation with nirS gene abundance and were the dominant genera under florfenicol stress. Our study provided a scientific basis for the rational use of florfenicol in aquaculture to maintain a healthy and stable microecological environment, and also provided a preliminary understanding of the response characteristics of water denitrifying microorganisms to florfenicol exposure.

Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The focus of the study is to elucidate the direct photolysis mechanism of FLO in the water environment and the indirect photolysis of free radicals (·OH, ·NO3, and ·SO4−) as active species. The effect of metal ions Ca2+/Mg2+/Zn2+ on the indirect photolysis was also investigated. The results show that the direct photolysis of FLO involves C–C/C–N/C–S bond cleavage, the C5–S7 bond cleavage is most likely to occur, and the C17–C18 cleavage reaction is not easy to occur during the direct photodegradation of FLO. The indirect photolysis of FLO is more likely to occur in the environment than direct photolysis. The main indirect photolysis involves OH-addition, NO3-addition, and SO4-addition on benzene ring. The order of difficulty in the indirect photolysis with ·OH is C2 > C3 > C4 > C5 > C6 > C1, Ca2+ can promote the indirect photolysis with ·OH, and Mg2+/Zn2+ has a dual effect on the indirect photolysis with ·OH. In other words, Mg2+ and Zn2+ can inhibit or promote the indirect photolysis with ·OH. These studies provide important information for theoretical research on the environmental behavior and degradation mechanism of drug molecules.

Florfenicol is a promising antibiotic for use in companion animals, especially as an alternative agent for infections caused by MDR bacteria. However, the emergence of resistant strains could hinder this potential. In this study, florfenicol resistance was investigated in a total of 246 MDR Enterobacterales obtained from canine and feline clinical samples in Greece over a two-year period (October 2020 to December 2022); a total of 44 (17,9%) florfenicol-resistant strains were recognized and further investigated. Most of these isolates originated from urine (41.9%) and soft tissue (37.2%) samples; E. coli (n = 14) and Enterobacter cloacae (n = 12) were the predominant species. The strains were examined for the presence of specific florfenicol-related resistance genes floR and cfr. In the majority of the isolates (31/44, 70.5%), the floR gene was detected, whereas none carried cfr. This finding creates concerns of co-acquisition of plasmid-mediated florfenicol-specific ARGs through horizontal transfer, along with several other resistance genes. The florfenicol resistance rates in MDR isolates seem relatively low but considerable for a second-line antibiotic; thus, in order to evaluate the potential of florfenicol to constitute an alternative antibiotic in companion animals, continuous monitoring of antibiotic resistance profiles is needed in order to investigate the distribution of florfenicol resistance under pressure of administration of commonly used agents.

A method utilizing high-performance liquid chromatography-fluorescence detection (HPLC–FLD) has been developed and refined for the simultaneous detection of florfenicol (FF) and its metabolite florfenicol amine (FFA) along with three fluoroquinolone (ciprofloxacin (CIP), enrofloxacin (ENR), and sarafloxacin (SAR)) residues in different parts of eggs (whole egg, egg yolk, and egg albumen). The QuEChERS (“Quick, easy, cheap, effective, rugged, and safe”) procedure utilized 0.1 M disodium EDTA solution, water, and acetonitrile as extractants; sodium sulfate, sodium chloride, and trisodium citrate as dehydrating salts; and N-propylethylenediamine and C18 as adsorbents. A dual-channel FLD method was utilized to analyze the target compounds using an XBridge BEH C18 chromatographic column (4.6 mm × 150 mm, 5 μm). The mobile phase was employed isocratically using a solution of 0.01 M sodium dihydrogen phosphate, 0.005 M sodium dodecyl sulfate, and 0.1% triethylamine (pH 4.8) in combination with acetonitrile at a ratio of 65:35 (V/V). The limits of detection (LOD) and quantification (LOQ) of the analytes ranged from 0.03 to 1.5 µg/kg and from 0.1 to 5.0 µg/kg, respectively. The recoveries of the analytes in the blank egg samples ranged from 71.9% to 94.8% when reference standard concentrations of the LOQ, half of the maximum residual limit (MRL), MRL, and twice the MRL were added. The parameters of the presented protocol were validated and subsequently applied to the analysis of real samples, demonstrating the applicability and reliability of the method.

BACKGROUND:Drug-resistant fish pathogens can cause significant economic loss to fish farmers. Since 2012, florfenicol has become an approved drug for treating both septicemia and columnaris diseases in freshwater fish. Due to the limited drug options available for aquaculture, the impact of the therapeutical florfenicol treatment on the microbiota landscape as well as the resistome present in the aquaculture farm environment needs to be evaluated. RESULTS:Time-series metagenomic analyses were conducted to the aquatic microbiota present in the tank-based catfish production systems, in which catfish received standard therapeutic 10-day florfenicol treatment following the federal veterinary regulations. Results showed that the florfenicol treatment shifted the structure of the microbiota and reduced the biodiversity of it by acting as a strong stressor. Planctomycetes, Chloroflexi, and 13 other phyla were susceptible to the florfenicol treatment and their abundance was inhibited by the treatment. In contrast, the abundance of several bacteria belonging to the Proteobacteria, Bacteroidetes, Actinobacteria, and Verrucomicrobia phyla increased. These bacteria with increased abundance either harbor florfenicol-resistant genes (FRGs) or had beneficial mutations. The florfenicol treatment promoted the proliferation of florfenicol-resistant genes. The copy number of phenicol-specific resistance genes as well as multiple classes of antibiotic-resistant genes (ARGs) exhibited strong correlations across different genetic exchange communities (p

Antimicrobial resistance (AMR) poses a significant threat to both human and animal health, necessitating the search for alternative antimicrobial agents and strategies. In this study, we aimed to identify and isolate clinical bacterial strains from chickens and evaluate their sensitivity to florfenicol, a common antimicrobial agent that is used exclusively in veterinary medicine, along with polymeric nanoparticles loaded with florfenicol at various concentrations. Three clinical bacterial strains were successfully isolated and identified from chicken presenting clinical signs. In order to assess their susceptibility, the isolated strains were subjected to a standard disc diffusion assay using florfenicol. Subsequently, polymeric nanoparticles loaded with florfenicol were tested at six different concentrations and compared their efficacy against the bacterial strains. Our results demonstrated that all three clinical bacterial strains exhibited varying degrees of resistance to florfenicol. Interestingly, the use of polymeric nanoparticles loaded with florfenicol did not display enhanced antimicrobial activity compared to the free drug. Notably, the efficacy of the loaded nanoparticles did not significantly vary with different concentrations of active substance. This study highlights the importance of exploring novel therapeutic approaches to combat antimicrobial resistance. The use of polymeric nanoparticles loaded with florfenicol presents a promising avenue for overcoming resistance mechanisms and improving the efficacy of antimicrobial treatments both in human and veterinary medicine. Further investigations are needed to elucidate the underlying mechanisms and optimize the formulation of polymer nanoparticles for enhanced therapeutic outcomes in combating AMR.

BackgroundLinezolid is a critically important oxazolidinone antibiotic used in human medicine. Although linezolid is not licensed for use in food-producing animals, the use of florfenicol in veterinary medicine co-selects for oxazolidinone resistance genes.ObjectiveThis study aimed to assess the occurrence of cfr, optrA, and poxtA in florfenicol-resistant isolates from beef cattle and veal calves from different herds in Switzerland.MethodsA total of 618 cecal samples taken from beef cattle and veal calves at slaughter originating from 199 herds were cultured after an enrichment step on a selective medium containing 10 mg/L florfenicol. Isolates were screened by PCR for cfr, optrA, and poxtA which are genes known to confer resistance to oxazolidinones and phenicols. One isolate per PCR-positive species and herd was selected for antimicrobial susceptibility testing (AST) and whole-genome sequencing (WGS).ResultsOverall, 105 florfenicol-resistant isolates were obtained from 99 (16%) of the samples, corresponding to 4% of the beef cattle herds and 24% of the veal calf herds. Screening by PCR revealed the presence of optrA in 95 (90%) and poxtA in 22 (21%) of the isolates. None of the isolates contained cfr. Isolates included for AST and WGS analysis were Enterococcus (E.) faecalis (n = 14), E. faecium (n = 12), E. dispar (n = 1), E. durans (n = 2), E. gallinarum (n = 1), Vagococcus (V.) lutrae (n = 2), Aerococcus (A.) urinaeequi (n = 1), and Companilactobacillus (C.) farciminis (n = 1). Thirteen isolates exhibited phenotypic linezolid resistance. Three novel OptrA variants were identified. Multilocus sequence typing identified four E. faecium ST18 belonging to hospital-associated clade A1. There was a difference in the replicon profile among optrA- and poxtA-harboring plasmids, with rep9 (RepA_N) plasmids dominating in optrA-harboring E. faecalis and rep2 (Inc18) and rep29 (Rep_3) plasmids in poxtA-carrying E. faecium.ConclusionBeef cattle and veal calves are reservoirs for enterococci with acquired linezolid resistance genes optrA and poxtA. The presence of E. faecium ST18 highlights the zoonotic potential of some bovine isolates. The dispersal of clinically relevant oxazolidinone resistance genes throughout a wide variety of species including Enterococcus spp., V. lutrae, A. urinaeequi, and the probiotic C. farciminis in food-producing animals is a public health concern.

Florfenicol (FLR), a broad-spectrum antibacterial agent, is commonly used in the breeding and cultivation of aquatic animals. microRNAs (miRNAs) control gene expression by mediating post-transcriptional mRNA repression. However, not much has been reported regarding their functions when crustaceans encounter FLR stress. Herein we observed histological alterations and performed small RNA sequencing to characterize differentially expressed miRNAs in the hepatopancreas of Portunus trituberculatus exposed to FLR (80 mg/kg) stress for 3 h and 12 h. Our results indicated irregularities in the tubular structure of hepatopancreas, separation between epithelium and myoepithelial layer, ruptured epithelial cells, and tubule degeneration. Thirty-five (19 up- and 16 downregulated) and 31 (17 up- and 14 downregulated) differentially expressed miRNAs were detected between Group-C and Group-FLR-3 h and between Group-C and Group-FLR-12 h, respectively. Dual luciferase reporter assay was performed for predicting target genes of miR-34 and miR-263b. We found that mir-263b directly inhibited cytochrome C expression at the cell level in vitro. Functional analyses of predicted target genes of differentially expressed miRNAs revealed that FLR stress induced xenobiotic metabolism, immune toxicity, and cell apoptosis, as well as influenced diverse metabolic processes. To our knowledge, this is the first report on the response of P. trituberculatus to FLR stress. Our findings provide evidence that miRNAs participate in cell apoptosis and immune regulation in crabs.

Excessive use of antibiotics in aquaculture causes residues in aquatic animal products and harms human health. However, knowledge of florfenicol (FF) toxicology on gut health and microbiota and their resulting relationships in economic freshwater crustaceans is scarce. Here, we first investigated the influence of FF on the intestinal health of Chinese mitten crabs, and then explored the role of bacterial community in FF-induced intestinal antioxidation system and intestinal homeostasis dysbiosis. A total of 120 male crabs (48.5 ± 4.5 g) were experimentally treated in four different concentrations of FF (0, 0.5, 5 and 50 μg/L) for 14 days. Responses of antioxidant defenses and changes of gut microbiota were assessed in the intestine. Results revealed that FF exposure induced significant histological morphology variation. FF exposure also enhanced immune and apoptosis characteristics in the intestine after 7 days. Moreover, antioxidant enzyme catalase activities showed a similar pattern. The intestinal microbiota community was analyzed based on full-length 16S rRNA sequencing. Only the high concentration group showed a marked decrease in microbial diversity and change in its composition after 14 days of exposure. Relative abundance of beneficial genera increased on day 14. These findings illustrate that exposure to FF could cause intestinal dysfunction and gut microbiota dysbiosis in Chinese mitten crabs, which provides new insights into the relationship between gut health and gut microbiota in invertebrates following exposure to persistent antibiotics pollutants. [ABSTRACT FROM AUTHOR]

Starvation has influence on physiology and pharmacokinetic (PK) characteristics of many drugs in land animals. However, similar PK information in fish is lacking. The current study examined the effects of starvation on fish PK, taking florfenicol (FF) in Asian seabass as an example. FF was orally administered at a single dose of 10 mg/kg into 35‐day starved fish reared at 25 and 30°C and the serum FF concentration was analyzed by HPLC‐FLD. At 30°C, the absorption and elimination half‐lives of the starved fish were increased by 30% (from 0.44 to 0.57 h) and 55% (from 7.2 to 11.18 h), respectively. The volume of distribution, clearance, and area under the curve were changed from 1.25 to 0.71 L/kg, 0.120 to 0.044 L/kg/h, and 88 to 228 h·μg/ml, respectively. Similar starvation‐induced PK changes were also observed at 25°C. The serum biochemical parameters, mainly the alanine aminotransferase, aspartate aminotransferase, and glucose levels, were significantly reduced in the starvation group. Overall, FF absorption, distribution, and elimination rates were reduced by starvation, resulting in four to five times lower optimal dosage than the non‐starved fish. Drug treatment in starved fish should be treated with caution as overdosing and/or tissue residues could perceivably occur. [ABSTRACT FROM AUTHOR]

Coptisine (COP) is the main active ingredient of Coptis chinensis. In Chinese veterinary clinics, Coptis chinensis is commonly used alongside florfenicol to treat intestinal infections. The goal of this study was to investigate the impact of COP co-administration on the pharmacokinetics of florfenicol in rats. Male Sprague-Dawley rats were orally administered COP (50 mg/kg BW) or sterile water for 7 consecutive days, followed by a single oral dose of florfenicol (25 mg/kg BW) on the 8th day. Pharmacokinetics of florfenicol were analysed using non-compartmental methods, while expression levels of cytochrome P450 (CYP) isoforms in the liver and P-glycoprotein (P-gp) in the jejunum were measured using real-time RT-PCR, Western blot and immunohistochemical analyses. Co-administration of COP and florfenicol significantly increased AUC(0-∞), MRT(0-∞), and Cmax of florfenicol, while CLz/F was significantly decreased. COP down-regulated the expression of CYP1A2, CYP2C11, and CYP3A1 in the liver, as well as P-gp in the jejunum. These findings suggest that co-administration of COP with florfenicol alters the pharmacokinetics of florfenicol in rats. The down-regulation of CYP and P-gp expression may contribute to this effect. Therefore, the co-administration of COP with florfenicol may enhance the prophylactic or therapeutic efficacy of florfenicol in veterinary practice. [ABSTRACT FROM AUTHOR]

Widespread and inappropriate use of antibiotics has been shown to increase the spread of antibiotics and antimicrobial resistance genes (ARGs) in aquatic environments and organisms. Antibiotic use for the treatment of human and animal diseases is increasing continuously globally. However, the effects of legal antibiotic concentrations on benthic consumers in freshwater environments remain unclear. In the present study, we tested the growth response of Bellamya aeruginosa to florfenicol (FF) for 84 days under high and low concentrations of sediment organic matter (carbon [C] and nitrogen [N]). We characterized FF and sediment organic matter impact on the bacterial community, ARGs, and metabolic pathways in the intestine using metagenomic sequencing and analysis. The high concentrations of organic matter in the sediment impacted the growth, intestinal bacterial community, intestinal ARGs, and microbiome metabolic pathways of B. aeruginosa. B. aeruginosa growth increased significantly following exposure to high organic matter content sediment. Proteobacteria, at the phylum level, and Aeromonas at the genus level, were enriched in the intestines. In particular, fragments of four opportunistic pathogens enriched in the intestine of high organic matter content sediment groups, Aeromonas hydrophila, Aeromonas caviae, Aeromonas veronii, and Aeromonas salmonicida, carried 14 ARGs. The metabolic pathways of the B. aeruginosa intestine microbiome were activated and showed a significant positive correlation with sediment organic matter concentrations. In addition, genetic information processing and metabolic functions may be inhibited by the combined exposure to sediment C, N, and FF. The findings of the present study suggest that antibiotic resistance dissemination from benthic animals to the upper trophic levels in freshwater lakes should be studied further. [ABSTRACT FROM AUTHOR]

Antibiotic residue may pose a serious risk to aquaculture, and the culture of Litopenaeus vannamei in a low-salinity environment is a growing trend over the world. Here, we aimed to understand the combined effect of low salinity and sulfamethoxazole (SMZ) and florfenicol (FLO) antibiotics on L. vannamei. The growth performance, immune functions, antioxidant capacity and intestinal microbiota were investigated. Compared with the control group, the weight gain and survival rate significantly decreased (p < 0.05) in shrimp after they were exposed to low-salinity (salinity 3) water and the mixture of antibiotics and low-salt conditions for 28 days. The antioxidant activities of SOD and T-AOC, shown at low salinity and in the higher concentration of the SMZ treatment group (SMZH), were significantly decreased, while the GST activity was significantly increased in each treatment group in comparison with the control group. The expression of immune-related genes, including TOLL, LvIMD, PPO and HSP, in the low concentration of the SMZ treatment group (SMZL) was higher than that in the other groups. The diversity of intestine microbiota was disturbed with a lower Shannon index in the low-salinity and SMZH groups, and a higher Simpson index in the SMZH group. Proteobacteria, Actinobacteria and Bacteroidetes were the dominant phyla in the gut of L. vannamei. At the genus level, Microbacterium, Shewanella, Aeromonas, Acinetobacter, Gemmobacter, Paracoccus and Lysobacter were significantly decreased in the low-salinity group. However, the abundance of opportunistic pathogens belonging to the genus Aeromonas in the FLO group was increased. The predicted microbe-mediated functions showed that the pathway for "amino acid metabolism" and "replication and repair" was significantly inhibited in both the low-salinity and antibiotic-exposed groups. All the findings in this study indicate that the combined effect of antibiotics and low salinity on L. vannamei negatively impacted the physiological and intestinal microbiota functions. [ABSTRACT FROM AUTHOR]

The diversity and composition of intestinal microbiota in rainbow trout have been studied using next-generation sequencing (NGS), although few studies have examined the effects of antimicrobials. We evaluated the effect of antibiotics florfenicol and erythromycin and infection with or without Flavobacterium psychrophilum on the intestinal microbiota in rainbow trout juveniles (30–40 g) using NGS. Prophylactic oral antibiotic treatments were administered for 10 days before groups of fish were injected intraperitoneally with virulent F. psychrophilum. Intestinal content (allochthonous bacteria) was collected at day −11, 0, 12, and 24 p.i., and the v3–v4 region of the 16S rRNA gene was sequenced using Illumina MiSeq. Before prophylactic treatment, Tenericutes and Proteobacteria were the most abundant phyla identified and Mycoplasma was the most abundant genus. Fish infected with F. psychrophilum had decreased alpha diversity and a high abundance of Mycoplasma. Fish administered florfenicol had increased alpha diversity compared to the control at day 24 p.i., although both florfenicol and erythromycin-treated fish had a higher abundance of potential pathogens, specifically Aeromonas, Pseudomonas, and Acinetobacter. Mycoplasma disappeared after treatment but appeared again after day 24. This study demonstrates that prophylactic oral treatment with antibiotics florfenicol and erythromycin as well as F. psychrophilum infection changed the composition of intestinal microbiota in rainbow trout juveniles that did not recover by day 24 p.i. and further long-term effects on the host need to be investigated. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]

Background: Avian pathogenic Escherichia coli (APEC) are considered a growing health problem to both poultry and the public, particularly due to its multi-drug resistance. Zinc oxide nanoparticles (ZnO-NPs) are a promising multi-benefit candidate. This study focused on boosting the antimicrobial effect of the chemically synthesized ZnO-NPs using Polyethylene glycol-6000 (PEG-6000) and evaluating their potential to recover the sensitivity of Florfenicol and Streptomycin-resistant APEC to these drugs in a concentration range of 0.1–0.4 mg/mL. Four samples of ZnO-NPs were formulated and tested microbiologically. Results: The physicochemical characterization showed well-crystallized spherical in situ synthesized ZnO-NPs using PEG-6000 (surfactant) and ethanol (co-surfactant) of ∼19–67 nm particle size after coating with PEG-6000 molecules. These ZnO-NPs demonstrated a strong concentration-dependent antibacterial effect against multidrug-resistant APEC strains, with a minimum inhibitory concentration of 0.1 mg/mL, Combining PEG-6000 coated in situ synthesized ZnO-NPs and Florfenicol induced 60% high sensitivity (30 mm inhibitory-zone), 30% intermediate sensitivity, and 10% resistance against APEC strains. The combination with Streptomycin revealed 50% high sensitivity, 30% intermediate sensitivity, and 20% resistance with a 20 mm maximum zone of inhibition using agar well diffusion test. Conclusion: In situ preparation of ZnO-NPs using PEG-6000 and ethanol followed by coating with PEG-6000 enhanced its antibacterial activity in minimum inhibitory concentration and regained the efficacy of Florfenicol and Streptomycin against APEC, referring to a non-antibiotic antimicrobial alternative and an effective combination regimen against multidrug-resistant APEC E. coli in veterinary medicine. [ABSTRACT FROM AUTHOR]

Asian seabass (Lates calcarifer) is an economically important fish in Asian and Australian markets, but few pharmacokinetic (PK) data of antimicrobial drugs in this species is available. The present study investigated the PK behaviour of florfenicol (FF) through medicated feed in Asian seabass cultured at 25°C. The serum and muscle/skin concentrations of FF and its metabolite florfenicol amine (FFA) were determined by the HPLC‐FLD method and analysed by one‐compartmental model. The optimal dosages were determined by pharmacokinetic‐pharmacodynamic (PK‐PD) approach and the linear regression analysis was used to determine the withdrawal time (WDT). The PK study following a single oral administration of 15 mg/kg FF via medicated feed revealed that the absorption half‐life (t1/2Ka), elimination half‐life (t1/2K), peak concentration (Cmax), area under the concentration‐time curve (AUC), volume of distribution (Vd/F) and clearance (CL/F) were 1.47 h, 8.07 h, 8.61 μg/ml, 146.41 h·μg/ml, 1.19 L/kg and 0.102 L/kg/h, respectively. The muscle/skin concentration‐time profile was similar to that of the serum, suggesting well distribution but only a small fraction of FF was metabolized to FFA. The optimal dosage for a minimum inhibitory concentration of 2 μg/ml was calculated as 13.38 mg/kg/day. The appropriate WDT after multiple oral medications with 15 mg/kg FF once daily for 7 days was determined as 8 days. Information obtained from the current study can potentially be applied for the treatment of bacterial diseases in farming Asian seabass. [ABSTRACT FROM AUTHOR]

The pharmacokinetic variables of a new formulation of florfenicol included in dried bean of alginate (FADBs), its acceptance as in food medication, and its relationship with theoretical minimum inhibitory concentration (MIC) values of the main pathogens in rabbits, are presented. FADBs sought to mask the unpleasant taste of florfenicol while enhancing sustained absorption in a day to facilitate and optimise its dosage in this species. The entrapment efficiency was determined to be 94-98% and 73.56±3.26% of drug loading. No reduction in food consumption was detected, nor selectivity when choosing from their usual food. The elimination half-life was 1.23 to 2.4 h slower than the one previously reported in the literature. Possible flip-flop pharmacokinetics is proposed for FADBs in rabbits, thus complying better with the key pharmacokinetics/pharmacodynamics (PK/PD) ratio of t≥MIC. Also, if a MIC2.0 μg/mL is taken as the cut-off point for florfenicol in rabbits, then ad libitum intake of FADBs in their standard diet is sufficient to maintain plasma concentrations of florfenicol above this level during the whole dosing interval of 24 h. Additionally, FADBs are a low-cost and attractive drug delivery system for the oral controlled release of florfenicol in rabbits.