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To our knowledge, ours is the first study to investigate the annual fluxes, environmental fate, and ecological risks of five categories of antibiotics from the Wuhan section of the Yangtze River (China). All the 24 antibiotics we tested for were detected in water, with total concentrations of 17.11–867.2 ng/L (mean: 63.69 ng/L), and 19 antibiotics were detected in sediment, at 0.02–287.7 ng/g (mean: 16.54 ng/g). Sulfonamides, amphenicols, and macrolides were the three most prominent antibiotic classes in water, and fluoroquinolones were the most prominent in sediment. Farming activities (animal husbandry and aquaculture) are proposed as the largest contributors to antibiotic pollution in the Wuhan section of the Yangtze River according to the Unmix model, followed by municipal wastewater and mixed sources. Higher pollution levels were observed downstream (combined discharge of these sources). Monthly monitoring data (12 months) were used to estimate antibiotic annual fluxes, with 101.5 t (uncertainty: 5.6%) in the Wuhan section of the Yangtze River. Risk assessments showed that erythromycin, clarithromycin, and azithromycin posed medium and high ecological risks and were found in 9%–35% and 1.8%–3.7% of all water samples, respectively; enrofloxacin, clarithromycin, azithromycin, florfenicol, and thiamphenicol posed medium resistance risks in 1.9%–16.7% of waters in the Wuhan section of the Yangtze River. Our results have filled data gaps on antibiotic sources, annual fluxes, and resistance risk in the Wuhan section of the Yangtze River and demonstrated the importance of further management of antibiotic use in the studied areas. Environ Toxicol Chem 2023;42:605–619. © 2022 SETAC [ABSTRACT FROM AUTHOR]

Antibiotic resistance mediated by bacterial enzyme inactivation plays a crucial role in the degradation of antibiotics in the environment. Chloramphenicol (CAP) resistance by enzymatic inactivation comprises nitro reduction, amide bond hydrolysis, and acetylation modification. However, the molecular mechanism of enzymatic oxidation of CAP remains unknown. Here, a novel oxidase gene, cmO, was identified and confirmed biochemically. The encoded CmO oxidase could catalyze the oxidation at the C-19 and C-39 positions of CAP and thiamphenicol (TAP) in Sphingobium sp. strain CAP-1. CmO is highly conserved in members of the family Sphingomonadaceae and shares the highest amino acid similarity of 41.05% with the biochemically identified glucose methanol choline (GMC) oxidoreductases. Molecular docking and site-directed mutagenesis analyses demonstrated that CAP was anchored inside the protein pocket of CmO with the hydrogen bonding of key residues glycine (G) 99, asparagine (N) 518, methionine (M) 474, and tyrosine (Y) 380. CAP sensitivity tests demonstrated that the acetyltransferase and CmO could enable a higher level of resistance to CAP than the amide bond-hydrolyzing esterase and nitroreductase. This study provides a better theoretical basis and a novel diagnostic gene for understanding and assessing the fate and resistance risk of CAP and TAP in the environment. [ABSTRACT FROM AUTHOR]

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]

The aim of this study was to assess the dynamics of microbial communities and antimicrobial resistance genes (ARGs) in the chicken gut following amoxicillin and thiamphenicol treatments and potential co-selection of ARGs. To this purpose, the microbial community composition, using 16S rRNA NGS, and the abundance of ARGs conferring resistance to β-lactams and phenicols, using qPCRs, were determined. Results revealed that the administered antimicrobials did not significantly reduce the gut microbiota diversity, but changed its composition, with taxa (e.g. Gallibacterium and Megamonas) being enriched after treatment and replacing other bacteria (e.g. Streptococcus and Bifidobacterium). Positive correlations were found between ARGs (e.g. cmlA, blaCMY-2, and blaSHV) and the relative abundance of specific taxa (e.g. Lactobacillus and Subdoligranulum). The selective pressure exerted by both amoxicillin and thiamphenicol resulted in an increased abundance of ARGs conferring resistance to β-lactams (e.g. blaTEM-1, blaSHV, and blaCTX-M1-like) and phenicols (e.g. floR and cmlA). These findings, together with the co-occurrence of genes conferring resistance to the two antimicrobial classes (e.g. blaTEM-1 and cmlA), suggest a possible interaction among antimicrobials on resistance emergence, possibly due to the presence of mobile genetic elements (MGEs) carrying multiple resistance determinants. [ABSTRACT FROM AUTHOR]

Activated carbon can be applied to the treatment of wastewater loading with different types of pollutants. In this paper, a kind of activated carbon in granular form (GAC) was utilized to eliminate antibiotics from an aqueous solution, in which Tetracycline (TC), Thiamphenicol (THI), and Sulfamethoxazole (SMZ) were selected as the testing pollutants. The specific surface area, total pore volume, and micropore volume of GAC were 1059.011 m2/g, 0.625 cm3/g, and 0.488 cm3/g, respectively. The sorption capacity of GAC towards TC, THI, and SMZ was evaluated based on the adsorption kinetics and isotherm. It was found that the pseudo-second-order kinetic model described the sorption of TC, THI, and SMZ on GAC better than the pseudo-first-order kinetic model. According to the Langmuir isotherm model, the maximum adsorption capacity of GAC towards TC, THI, and SMZ was calculated to be 17.02, 30.40, and 26.77 mg/g, respectively. Thermodynamic parameters of ΔG0, ΔS0, and ΔH0 were obtained, indicating that all the sorptions were spontaneous and exothermic in nature. These results provided a knowledge base on using activated carbon to remove TC, THI, and SMZ from water. [ABSTRACT FROM AUTHOR]

Previous studies implied that elevated exposure to amphenicol antibiotics may induce increased oxidative stress. However, the effects of amphenicol antibiotics exposure on oxidative stress damage in human have not been well studied. This study examined the associations between amphenicol antibiotics exposure and oxidative damage biomarkers in school children. Three major amphenicols including chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF) and two biomarkers of 8-hydroxydeoxyguanosine (8-OHdG) for oxidative DNA damage and 8-oxo-7,8- dihydroguanosine (8-OHG) for oxidative RNA damage were measured in 414 morning urine samples collected from 70 school children in Shanghai, China. School children were exposed to CAP, TAP, and FF with median concentrations of 1.37, 0.36, and 0.06 μg/g Cre, respectively. Linear mixed models revealed that an interquartile range (IQR) increase of urinary TAP was positively associated with 7.75%(95% CI: 4.40%, 11.1%) increase of 8-OHdG and 7.48%(95% CI: 2.49%, 15.6%) increase of 8-OHG, respectively; in addition, CAP was associated with elevated 8-OHdG. Although FF was not found to be significantly associated with either 8-OHdG or 8-OHG, it is warranted to further investigate FF and its metabolites levels in relation to oxidative stress in future study. Our findings provide new evidence for the effects of exposure to TAP and CAP on nucleic acid oxidative damage in Children. [ABSTRACT FROM AUTHOR]

Thiamphenicol (TAP) is an amphenicol antibiotic, which has a broad-spectrum inhibitory effect on both gram-positive and gram-negative bacteria. Since it is widely used in animals and aquaculture, its residues in environment may bring potential risk for human health and ecosystems. While TAP can be removed through conventional physical or chemical methods, its bioremediation using microorganisms is less studied. Here, we report the removal of TAP by a bacterial strain, Aeromonas hydrophila HS01, which can remove more than 90.0% of TAP in a living cell-dependent manner. Our results indicated that its removal efficiency can be greatly affected by the growth condition. Proteomics studies revealed a number of differentially expressed proteins of HS01 in the presence of TAP, which may play critical roles in the transportation and degradation of TAP. All these results indicate bacterial strain A. hydrophila HS01 is a new microbial resource for efficiently removing TAP, and may shed new insights in developing bioremediation approaches for TAP pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • •Co-MgO-CMS was prepared by MOFs derivatization. • •Co-MgO-CMS exhibited high activity and stability in ozonation of thiamphenicol. • •Metallic Co in Co-MgO-CMS could interact directly with O 3 to produce reactive oxygen species. Cobalt-magnesium oxide–carbon microsphere composite (Co-MgO-CMS), Cobalt-carbon nanosheet composite (Co-CNS), and magnesium oxide–carbon nanorod composite (MgO-CNR) were synthesized by the MOFs self-sacrificing template method. And they were used as the catalysts for catalytic ozonation of thiamphenicol (20 mg/L) in water at an initial pH of 7.0. The phase of Co-MgO-CMS is mainly composed of metallic cobalt, magnesium oxide and carbon according to X-ray diffraction and transmission electron microscopy analyses. Thiamphenicol removal efficiency is enhanced through Co-MgO-CMS catalytic ozonation (75.4 %, in 6 min), compared with those in ozonation alone (39.8 %), Co-CNS catalytic ozonation (43.2 %), MgO-CNR catalytic ozonation (65.1 %) and Mg-Co binary oxide (Mg 2 CoO y) catalytic ozonation (69.0 %). Self-increasing of solution pH, protonated hydroxyl groups and electron transfer on metallic Co and lattice Co2+ are advantageous for the ozone decomposition into reactive oxygen species in Co-MgO-CMS catalytic ozonation. Owing to the metallic Co in Co-MgO-CMS, the electron transfer ability of Co-MgO-CMS is better than that of Mg 2 CoO y according to the in situ electrochemical test. Moreover, electron transfers directly from metallic Co to ozone. While protonated hydroxyl groups are the key for electron transfer on lattice Co2+. A possible degradation pathway for thiamphenicol in Co-MgO-CMS catalytic ozonation is proposed according to the detected intermediates. This work provides insight into improvement on electron transfer ability of concerted acid-base catalyst in heterogeneous catalytic ozonation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A consortium proficient in TAP degradation was domesticated from activated sludge. • TAP metabolic fate, mechanism and cross-feeding were first unraveled by muti-omics. • Key species Hydrogenophaga and Bosea inactivated TAP by oxidation and acetylation. • Hydrogenophaga sp. stored carbon and nitrogen by synthesizing cyanophycin and PHB. Thiamphenicol (TAP), a typical veterinary antibiotic, is emerging as a contaminant in livestock, poultry, and aquaculture environments. Addressing this concern, this study domesticated a TAP-degrading consortium in a lab-scale activated sludge bioreactor, demonstrating efficient degradation of up to 200 mg/L TAP within 50 h and elimination of antimicrobial activity. The microbial compositions, cross-feeding interactions, and underlying metabolic mechanisms were unveiled through multi-omics. TAP was modified at two hydroxyl groups for the initial step in three pathways including oxidation at C 3 -OH, dehydrogenation at both C 1 -OH and C 3 -OH, and acetylation at C 3 -OH. Hydrogenophaga (MAG1 and MAG2) and Bosea (MAG9) were implicated in oxidation and acetylation of TAP, respectively. Aromatic compounds and 2,2-dichloroacetic acid (DCA) were the principal downstream metabolites of TAP. MAG9 (Bosea), MAG10 (Rubrivivax), and MAG13 (Hyphomicrobium) were predicted as DCA degraders, while MAG4 (Xanthobacteraceae, Ga0077548) and MAG10 (Rubrivivax) conducted the catabolism of aromatic compounds. Therefore, consortium members collaborated to efficiently reduce and detoxify TAP. Furthermore, the co-metabolism of TAP and extracellular substrates supported the microbial populations' growth. Genomic traits and transcriptional profiles suggested that the dominant Hydrogenophaga (MAG1) could store carbon and nitrogen by synthesizing cyanophycin and polyhydroxybutyrate biopolymers. Ultimately, this comprehensive understanding of TAP biodegradation will aid in formulating efficient biotreatment strategies for TAP-contaminated environments. [ABSTRACT FROM AUTHOR]

Amphenicol antibiotics including chloramphenicol (CAP), florfenicol (FF) and thiamphenicol (TAP) have been widely used in aquaculture and veterinary to treat various infections. Because of their high toxicity, it is important to detect these amphenicol antibiotics simultaneously. Using the monoclonal antibody against CAP (mAbCAP) binding CAP only and the mAbFF recognizing both FF and TAP, the two antibodies were covalently coupled to CNBr-activated Sepharose-4B for the simultaneous extraction of CAP, FF and TAP from samples. The bound CAP, FF and TAP were eluted from the Sepharose-4B and measured by LC–MS/MS. The extraction conditions of the two-antibodies-immobilized immunoaffinity clean-up (IAC) for CAP, FF and TAP were optimized and the maximum capacity was investigated. The extraction efficiency of IAC for CAP, FF and TAP was 1.1–2.1 times higher than that of SPE. The LC–MS/MS coupled with IAC was a powerful analytical method for the detection of CAP, FF and TAP simultaneously. [ABSTRACT FROM AUTHOR]

The specific concentrations of florfenicol and thiamphenicol in non‐target feed for food‐producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield, were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties, are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. The FARSC for florfenicol was estimated. However, due to the lack of data, the calculation of the FARSC for thiamphenicol was not possible until further experimental data become available. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels in feed that showed to have an effect on growth promotion/increased yield were reported for florfenicol, whilst for thiamphenicol no suitable data for the assessment were available. Uncertainties and data gaps associated to the levels reported were addressed. For florfenicol, it was recommended to perform further studies to supply more diverse and complete data related to the requirements for calculation of the FARSC, whereas for thiamphenicol, the recommendation was to generate the data required to fill the gaps which prevented the FARSC calculation. [ABSTRACT FROM AUTHOR]

Suspended particles (SP) exist widely in various water systems and are able to adsorb other pollutants in water, producing ecotoxic effects on aquatic nontarget species. Until now, however, few studies have focused on the effects of SP on antibiotics. Therefore, the present study investigated the effects of the mixtures of SP and phenicol antibiotics (chloramphenicol [CAP], thiamphenicol [TAP]) on acute toxicity and oxidative stress responses in Daphnia magna. The results indicated that the acute toxicity of phenicol antibiotics in D. magna was increased when combined with SP. Besides, the immobilization of daphnids caused by phenicol drugs in the presence of 10 mg/L of SP was more intense than that with 200 mg/L of SP. Furthermore, the impact of SP with diverse concentrations on the activity of catalase and the level of reduced glutathione in D. magna was different. Notably, almost all CAP + TAP + SP treatments markedly increased malondialdehyde content in D. magna, causing potential cellular oxidative damage in D. magna. In summary, the present study provides insights into the toxic effects of phenicol antibiotic and SP mixtures on aquatic organisms. Environ Toxicol Chem 2021;40:2463–2473. © 2021 SETAC [ABSTRACT FROM AUTHOR]

l‐Threonine aldolase from Actinocorallia herbida (AhLTA) is an ideal catalyst for producing l‐threo‐4‐methylsulfonylphenylserine [(2S,3R)‐1 b], a key chiral precursor for florfenicol and thiamphenicol. The moderate Cβ stereoselectivity is the main obstacle to the industrial application of AhLTA. To address this issue, a combinatorial active‐site saturation test (CAST) together with sequence conservatism analysis was applied to engineer the AhLTA toward improved Cβ stereoselectivity. The optical mutant Y314R could asymmetrically synthesize l‐threo‐4‐methylsulfonylphenylserine with 81 % diastereomeric excess (de), which is 23 % higher than wild‐type AhLTA. Molecular dynamic (MD) simulations revealed that the mechanism for the improvement in Cβ stereoselectivity of Y314R is due to the acylamino group of residues Arg314 controlling the orientation of substrate 4‐methylsulfonyl benzaldehyde (1 a) in the active pocket by directed interaction with the methylsulfonyl group; this leads to asymmetric synthesis of l‐threo‐4‐methylsulfonylphenylserine. The success in this study demonstrates that direct control of substrates in an active pocket is an attract strategy to address the Cβ stereoselectivity problem of LTA and contribute to the industrial application of LTA. [ABSTRACT FROM AUTHOR]

Thiamphenicol (TM) is an antimicrobial drug and a methyl-sulfonyl analogue of chloramphenicol. New metal complexes of TM with Zn(II), Cu(II), Ni(II), Co(II) and Fe(II) were synthesized and characterized using elemental analyses, infrared (IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR), magnetic susceptibility, electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). The IR spectra revealed coordination of the deprotonated ligand to the metal through one oxygen and the nitrogen atom of the amide group. Moreover, EPR analysis of the Cu(II) solid sample indicated a distorted tetrahedral structure with a negligible exchange interaction between the Cu(II) ions. The UV-vis spectral results from the Co(II) and Fe(II) complexes showed a distorted tetrahedral geometric arrangement for both compounds. The DFT calculation approach was used to study the nature of the interaction between the metal ions and the ligand where the molecular stability and bond strengths were evaluated by Natural Bond Orbital (NBO) and quantum parameters. The biological activity of the metal complexes was investigated by several different bioassays. The DNA binding constant Kb showed an intercalation binding mode for both the free drug and the metal compounds. An in vitro protein (HSA) binding study showed binding with TM–Zn Kb = 9.87 × 105 M−1. The cytotoxic activity of each divalent complex was tested against two cell lines: (1) a human colon carcinoma (HCT-116) cell line and (2) a human breast carcinoma (MCF-7) tumor cell line and demonstrated anti-cancer cell activities. Molecular docking was utilized to explain the biological inhibition of the Cu(II) and Zn(II) complexes. [ABSTRACT FROM AUTHOR]

1. This study evaluated the pharmacokinetic profiles of florfenicol (FF) and thiamphenicol (TP), which are synthetic bacteriostatic antimicrobial drugs, in geese after a single intravenous or oral administration, as well as seven oral doses administered at 12 h intervals. For all treatments, the dose was 30 mg/kg. 2. After single IV administration, clearance and volume of distribution were low (0.23 ± 0.03 l/h/kg and 0.57 ± 0.08 l/kg for FF, and 0.23 ± 0.04 l/h/kg and 0.59 ± 0.08 l/kg for TP, respectively). The elimination half-life was similar between products and short (2.91 ± 0.41 and 2.84 ± 0.64 h for FF and TP, respectively). 3. The single oral administration resulted in efficient absorption (bioavailability of 83.15 ± 11.48 for FF and 75.21 ± 19.56% for TP) with high maximal concentrations of 30.47 ± 2.47 and 20.02 ± 3.87 μg/ml for FF and TP, respectively. The area under the curve was 108.36 ± 14.96 and 101.81 ± 26.48 mg×h/l for FF and TP, respectively. 4. For both drugs, the two latter parameters were found to be higher compared to earlier studies on terrestrial birds. This suggested that FF and TP may be efficient in treating infections in geese caused by certain bacteria sensitive to chloramphenicol. 5. Neither drug accumulated in tissues following the oral seven doses and no adverse effects were noted in any treated animals. Thus, the selected FF and TP dosage may be considered as a safe treatment for geese. [ABSTRACT FROM AUTHOR]

Thiamphenicol (TAP) and florfenicol (FFC) combination has in vitro and in vivo synergistic activity against fish bacterial pathogens. However, a lack of information on its pharmacokinetics (PK) and pharmacodynamics (PD) in fish limits its further application. Therefore, this study aimed to develop and validate analytical methods for simultaneous detection and quantification of TAP and FFC in tilapia plasma and muscle plus skin samples and to determine the PK in freshwater tilapia at 30 ± 0.32 °C after a single oral dose of 5 mg kg−1 TAP +3.75 mg kg−1 FFC. Antimicrobial concentrations were analyzed by HPLC-MS. The PK characteristics were estimated by a non-compartmental model (linear up/log down). Precise, and sensitive methods were developed using ethyl acetate (plasma) and a modified QuEChERS (muscle plus skin) for extraction. Both methods were successfully applied to analyze the plasma and muscle plus skin samples in the PK study. The highest concentrations of TAP and FFC were detected at 0.5 h (6.34 and 3.34 μg mL−1) and 16 h (8.20 and 11.37 μg mL−1) post-administration in plasma and muscle, respectively. There was no significant difference between the peak concentration and apparent volume of distribution during the terminal phase of each antimicrobial in different tissues. However, the peak time, the area under the concentration-time curve, and mean residence time were higher in the muscle, for both antimicrobials (P < 0.05). The calculated PK parameters and the curve obtained for both antimicrobials emphasize their fast absorption and distribution even when used in combination. The results from this study could help establish antimicrobial susceptibility testing interpretative categories and design rational dosing regimens for TAP and FFC combination. • Plasma and muscle plus skin pharmacokinetics of TAP and FFC in tilapia after single oral administration of TAP + FFC combination were determined for the first time. • The developed and validated HPLC-MS/MS method is precise and sensitive for the simultaneous determination of TAP and FFC in fish plasma and muscle plus skin. • TAP and FFC had fast absorption and distribution in freshwater tilapia reared at 30 ± 0.32 °C. • Peak concentrations in both tissues were 2–22 times higher than the reported MIC values of the antimicrobials against several sensitive fish pathogens. [ABSTRACT FROM AUTHOR]

Membrane fouling limited the application of membrane distillation (MD) process in resource recovery. In this research, the peroxymonosulfate (PMS) enhanced Fe(III) coagulation process was proposed and proved its effectiveness in eliminating natural organic matter (NOM) and emerging organic contaminants (EOCs). Fe(III)/PMS process significantly enhanced the removal of dissolved organic carbon (DOC), turbidity, and UV 254 , compared to conventional Fe(III) coagulation. Thiamphenicol (TAP) represented the EOCs in the digestate, and Fe(III)/PMS could significantly degrade TAP (86 % degradation). In this course, phenols/quinones served as electron shuttles to induce the Fe(III)/Fe (II) redox cycle. The activation of PMS was boosted, generating the primary reactive substance sulfate (SO 4 −) radical with intense oxidative properties. In addition, membrane distillation achieved recovery of 93 % of TAN from coagulation effluent without membrane fouling. No tryptophan-like, tyrosine-like, xanthate, and other soluble microbial byproducts were detected on the membrane surface following Fe(III)/PMS pretreatment. The innovation of this study was revealing that the complexation of Fe(III) with NOM could promote Fe (II) regeneration and enhance PMS activation, active substance formation and contaminants degradation. New insights into the role of NOM in the Fe(III)/Fe(II) redox cycle were gained and the development of advanced oxidation process (AOP) coupled membrane technology was promoted to mitigate membrane fouling. [Display omitted] • A coupled coagulation/advanced oxidation process-membrane distillation system was established for ammonia recovery. • The Fe(III)/PMS enhanced coagulation system significantly mitigated membrane fouling. • NOM could mediate the redox cycle of the Fe(III)/Fe(II). • The mechanism of degradation of TAP via Fe(III)/PMS system was proposed. • SO 4 •- was the prominent reactive radical in the Fe(III)/PMS process. [ABSTRACT FROM AUTHOR]

Thiamphenicol (TP) pharmacokinetics were studied in Japanese quails (Coturnix japonica) following a single intravenous (IV) and oral (PO) administration at 30 mg/kg BW. Concentrations of TP were determined with HPLC and were analyzed by a noncompartmental method. After IV injection, elimination half‐life (t1/2λz), total body clearance (Cltot) volume of distribution at steady state (Vdss), and mean residence time (MRT) of TP were 3.83 hr, 0.19 L/hr/kg, 0.84 L/kg, and 4.37 hr, respectively. After oral administration of TP, the peak plasma concentration (Cmax) was 19.81 μg/ml and was obtained at 2.00 hr (tmax) postadministration. Elimination half‐life (t1/2λz) and mean absorption time (MAT) were 4.01 hr and 1.56 hr, respectively. The systemic bioavailability following oral administration of TP was 78.10%. TP therapy with an oral dosage of 30 mg/kg BW is suggested for a beneficial clinical effect in quails. [ABSTRACT FROM AUTHOR]

Thiophenic compounds are major constituents of fossil fuels and pose problems for fuel refinement. The quantification and speciation of these compounds is of great interest in different areas such as biology, fossil fuels studies, geology, and archaeology. Sulfur 1s Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy has emerged as a qualitative and quantitative method for sulfur speciation. A firm understanding of the sulfur 1s NEXAFS spectra of organosulfur species is required for these analytical studies. To support this development, the sulfur 1s NEXAFS spectra of simple thiols and thioethers were previously examined, and are now extended to studies of thiophenic and aromatic thioether compounds, in the gas and condensed phases. High-resolution spectra have been further analyzed with the aid of Improved Virtual Orbital (IVO) and Δ(self-consistent field) ab initio calculations. Experimental sulfur 1s NEXAFS spectra show fine features predicted by calculation, and the combination of experiment and calculation has been used to improve the assignment of spectroscopic features important for the speciation and quantification of sulfur compounds. Systematic differences between gas and condensed phases are also explored; these differences suggest a significant role for conformational effects in the NEXAFS spectra of condensed species. [ABSTRACT FROM AUTHOR]

A convenient and inexpensive approach for the synthesis of deuterium-labeled thiamphenicol was described. DL-threo-Thiamphenicol-methyl-d3 was prepared with high chemical purity and isotopic enrichment via a six-step process starting from 4-bromobenzaldehyde and DMSO-d6 by employing microwave-assisted copper-mediated methylthiolation and modified Wulff's asymmetric aziridination. [ABSTRACT FROM AUTHOR]

Objectives: To assess the in vitro activities of acetylmidecamycin, a 16-membered macrolide, and 11 other antimicrobial agents against human mycoplasmas.Methods: A total of 187 clinical isolates, Mycoplasma pneumoniae (n = 110), Mycoplasma hominis (n = 26) and Ureaplasma species (n = 51), were included in this study. The MICs of 12 antimicrobial agents, including acetylmidecamycin, thiamphenicol, chloramphenicol and some other macrolides, fluoroquinolones and tetracyclines, for these clinical isolates were determined by the broth microdilution method.Results: For M. pneumoniae, the MIC90 values of the tested macrolides were: acetylmidecamycin (1 mg/L)128 mg/L). Thiamphenicol and chloramphenicol had the same MIC90 (2 mg/L). For Ureaplasma species, the MIC90 values were: acetylmidecamycin (0.25 mg/L)128 mg/L)=erythromycin. The MIC90 values of chloramphenicol and thiamphenicol were 2 and 4 mg/L, respectively.Conclusions: The results indicated that acetylmidecamycin and thiamphenicol are active in vitro against the most common mycoplasma species infecting humans, including those resistant to macrolides and fluoroquinolones. Acetylmidecamycin and thiamphenicol might be a promising option for clinicians to treat infections caused by Mycoplasma and Ureaplasma spp., particularly macrolide-resistant M. pneumoniae in paediatrics and fluoroquinolone-resistant M. hominis in adults. Further investigation of their clinical roles in treating infections caused by these organisms is warranted. [ABSTRACT FROM AUTHOR]

This study established a rapid and reliable method to determine chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF) residues in Chinese gelatin medicines. CAP, TAP and FF were extracted from medicine samples using 2% (v/v) ammonium hydroxide in acetonitrile. Trypsin was used to eliminate the matrix effect caused by protein components in gelatin medicines, whereas anhydrous sodium sulfate, C18-N and NH2-PSA adsorbents were applied to reduce matrix effect induced by other components. The analytical method of these drugs was optimized on ultra high-performance liquid chromatography-mass spectrometer (UHPLC-MS/MS) through the analysis of their standard linearity and regression. The optimized extraction and analytical method were validated in one Chinese gelatin medicine sample (Colla corii asini, E Jiao) with three fortification levels (2, 5 and 10 μg/kg), and the recoveries of these drug residues ranged of 87.6–102.7%. The limit of detection and quantification of CAP, TAP and FF in the sample were 0.2 and 0.5 μg/kg, 0.4 and 1.5 μg/kg, and 0.5 and 1.5 μg/kg, respectively. A total of 30 Chinese gelatin medicine samples were analyzed using the established method. No drug residues were found in these samples except for one Testudinis Carapacis et Plastri (1.67 μg/kg FF) and one turtle shell glue (2.55 μg/kg FF). [ABSTRACT FROM AUTHOR]

A general approach is presented for synthesis of multicolored gold nanoparticles (GNPs) by Au(I)-mediated generation of interlocking rings in proteins and antibiotics. The Au(I) ions are shuttled from proteins to antibiotics, and this causes the formation of interlocking rings. The multicolored GNPs of different sizes were synthesized in the rings by using the rapid nucleation method. To take the unique colors of GNPs, a functional array was designed for the colorimetric determination and discrimination of antibiotics, specifically of amoxicillin, chlortetracycline, erythromycin, spiramycin, neomycin, thiamphenicol, gentamycin and lincomycin. The method is based on the "three color" (RGB) principle. The color response patterns are characteristic for each antibiotic and can be quantitatively differentiated by statistical techniques. The limits of detection (LOD, at S/N = 3) for spiramycin (Sp) have been calculated to be 0.18 μM and 0.10 μM in water and milk, respectively. The good linear range (from 0.3 to 3.5 μM) has been used for the quantitative assay of Sp in a certified reference material. [ABSTRACT FROM AUTHOR]

A novel UV spectrophotometric method has been developed for the determination of thiamphenicol in a solid dosage form. The spectrophotometric detection was carried out at an absorption maximum wavelength of 224 nm using water as a solvent. The method was validated for specificity, linearity, precision, accuracy, robustness, and limit of detection (LOD) and limit of quantitation (LOQ). The detector response for thiamphenicol was linear in the selected concentration range of 5 to 25 μg/mL with a correlation coefficient of 0.9975. The precision (RSD) among six sample preparations was 0.65 and 1.50 % for analysts 1 and 2, respectively. The average recovery was 99.91 ± 0.65%. The LOD and LOQ were respectively 0.59 and 1.99 μg/mL. The results demonstrated that the excipients in thiamphenicol soft capsules did not interfere with the spectrophotometric determination of the drug. Using the Youden and Steiner approach, the method proved to be robust. The proposed method can be conveniently employed for routine analysis of thiamphenicol in bulk drug and soft capsules. [ABSTRACT FROM AUTHOR]

Agricultural waste-based activated carbon has been applied to the treatment of antibiotics-loaded wastewater recently. In this article, cornstalk was employed as a raw material to manufacture a kind of granular activated carbon (GAC), which was then used to remove four antibiotics, including isoniazid (IN), sulfamethoxazole (SMZ), thiamphenicol (THI), and doxycycline (DOX), from water. The as-prepared GAC had a rough and porous structure; the surface area and total pore volume were 944.71 m2/g and 0.56 cm3/g, respectively. Kinetic and isothermal models were established to analyze the sorption mechanism and evaluate the sorption performance. Pseudo-second-order kinetic model fitted the sorption of IN, SMZ, THI, and DOX on the GAC better than pseudo-first-order model. Based on the Langmuir isothermal model, the maximum sorption capacities (qm) of the GAC toward IN, SMZ, THI, and DOX were 27.0172, 36.9301, 28.0637, and 32.3902 mg/g, respectively. According to the Weber–Morris intraparticle diffusion model and the Boyd kinetics model, film diffusion was preponderant in the sorption process. Moreover, two-dimensional correlation spectroscopy integrated with Fourier-transform infrared spectroscopy was used to give the sequence of the different functional groups binding to the four antibiotics. To our knowledge, this is the first report on the sorption of IN, SMZ, THI, and DOX by cornstalk-based GAC. This work not only evaluated the application potential of cornstalk in the field of water purification but also provided a technical way for removing IN, SMZ, THI, and DOX from aqueous solution. [ABSTRACT FROM AUTHOR]

• TAP, FF and FFA was monitored and determined by UPLC-FLD. • A new method is used to detect TAP, FF and FFA residues in poultry meat and pork. • ASE was investigated as a rapid and automated approach. • The method provides reliable accuracy for determining TAP, FF and FFA. A method of accelerated solvent extraction coupled with ultra-performance liquid chromatography-fluorescence detection (ASE-UPLC-FLD) for the simultaneous detection of thiamphenicol, florfenicol and florfenicol amine residues in poultry meats (chicken muscle, duck muscle and goose muscle) and pork was developed and optimized. Samples were extracted with ASE using ethyl acetate:aqueous ammonia (98:2,V/V) as the extractant and purified with n-hexane saturated with ethyl acetate. Then, the samples were analyzed by UPLC-FLD. The excitation wavelength and emission wavelength of the fluorescence detector were 233 nm and 284 nm, respectively. The parameters of the optimized method were validated according to the requirements of the European Union and the Food and Drug Administration. The recoveries of the three analytes from poultry meats and pork at the limit of quantification (LOQ), 0.5 MRL (maximum residue limit), 1.0 MRL and 2.0 MRL were 80.80–98.35%, the relative standard deviations (RSDs) were less than 4.63%, and the intraday and interday RSDs were 2.22–5.54% and 2.42–6.08%, respectively. The limits of detection (LODs) and the LOQs were 1.0–4.2 μg/kg and 3.0–11.4 μg/kg, respectively. The new method was successfully applied for the quantitative determination of thiamphenicol, florfenicol and florfenicol amine residues in 40 poultry meat and pork samples from local supermarkets. [ABSTRACT FROM AUTHOR]

A simple and reliable method using liquid chromatography with diode array detector was developed for the simultaneous determination of florfenicol and thiamphenicol in medicated feed. The analytes were extracted from the minced feed with methanol and ethyl acetate (1:1, v/v). Next, the extract was further cleaned up by dispersive solid phase extraction using anhydrous magnesium sulfate, PSA and C18 sorbents. Finally, 1 mL of extract was evaporated, the residue resuspended in Milli-Q water, and filtered. The method was validated in-house at medicated levels, in the concentration range 10–300 µg/mL (50–1500 mg/kg). Values of <6.5% and <6.0% were found, respectively, for repeatability and within-laboratory reproducibility. The LODs for the two fenicols were 2.4–5.3 mg/kg, while the LOQs were 3.8–5.6 mg/kg. The expanded uncertainty was estimated to be in the range of 10.0–14.5%, depending on the analyte. Recoveries varied from 81.7% to 97.5%. The methodology was applied to the analysis of animal feedingstuffs collected from poultry and pig farms. [ABSTRACT FROM AUTHOR]

● High yields of DCAM and DCAA are formed during ozonation of phenicol antibiotics. ● The transformation pathways of phenicol antibiotics during ozonation are investigated. ● DCAM is completely transformed to DCAA during post-chlorination of ozonation effluent. ● The molar yield of DCAA is ∼100 % during phenicol antibiotic abatement by ozonation and post-chlorination. ● Post-chloramination of ozonation effluent increases the yields of DCAM and DCAA moderately. This study investigated the formation of dichloroacetamide (DCAM) and dichloroacetic acid (DCAA) from the abatement of three phenicol antibiotics (PABs, chloramphenicol, thiamphenicol, and florfenicol) during ozonation and post-chlor(am)ination. Results show that the three PABs have a low ozone reactivity (k O3 = 0.11‒0.12 M−1 s−1), and therefore are mainly abated through the hydrogen abstraction mechanism by hydroxyl radicals (•OH) during ozonation. During PAB degradation, the carboxamide moiety in the parent molecules can be cleaved off by •OH attack and thus gives rise to DCAM. The formed DCAM can then be further oxidized by O 3 and/or •OH to DCAA as a more stable transformation product (TP). When the three PABs were adequately abated (abatement efficiency of ∼82 %‒95 %), the molar yields of DCAM and DCAA were determined to be 2.79 %‒4.71 % and 32.9 %‒37.2 %, respectively. Furthermore, post-chloramination of the ozonation effluents increased the yields of DCAM and DCAA slightly to 4.20 %‒6.45 % and 39.0 %‒41.1 %, respectively. In comparison, post-chlorination eliminated DCAM in the solutions, but significantly increased DCAA yields to ∼100 % due to the further conversion of DCAM and other ozonation TPs to DCAA by chlorine oxidation. The results of this study indicate that high yields of DCAM and DCAA can be generated from PAB degradation during ozonation, and post-chlorination and post-chloramination will result in very different fates of DCAM and DCAA in the disinfected effluent. The formation and transformation of DCAM and DCAA during PAB degradation need to be taken into account when selecting multi-barrier treatment processes for the treatment of PAB-containing water. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The MIMFMs were endowed with superb hydrophilicity and permeability. • The MIMFMs had selective recognition and retention for three amphenicol drugs. • An efficient MIMFMs extraction strategy in syringe filter was developed. • MIMFMs-UHPLC-MS/MS analysis method for three amphenicols was established. In this study, molecularly imprinted microfiltration membranes (MIMFMs) based on polydopamine and metal–organic framework were innovatively proposed, and successfully prepared for capturing thiamphenicol, florfenicol and chloramphenicol from milk samples through syringe filter device. The provision of PDA and coupling of MOF particles enabled the filter membranes to have great permeability and binding capacity. Cleverly, hydrophilicity and heightened rebinding selectivity (IF = 2.42) of filter membranes was provided using two functional monomers (methacrylate and acrylamide), and microfiltration-grade composite membranes were generated by adjusting the imprinting polymerization time. The combination of the selective filter membranes and the syringe filter devices can effectively simplify the operation process, minimize the extraction time and reduce the tested sample volume. The method was validated by coupling with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and obtained a good correlation (r 2 > 0.99). The limit of detection (LOD) of three analytes was 0.0800–0.6583 µg kg−1 and the mean recovery ranged from 85.5% to 91.2% within relative standard deviations (RSDs) less than 8.2%. Finally, an effective MIMFMs-UHPLC-MS/MS method was established for the recognition and detection of three amphenicol antibiotics in milk samples. The MIMFMs filtration technique offered in this work provides valuable science references and potential application prospects for complicated sample pretreatment. [ABSTRACT FROM AUTHOR]

• Antibiotics inhibited potential sedimentary N removal and increased N 2 O yield. • Antibiotics had different effect on in situ sedimentary N removal along estuary. • Permeability of sediment determines the effect of antibiotics on N removal. • ARGs can't resist the inhibition of antibiotics on microbe related to N removal. Sedimentary denitrification takes place beneath the oxic layer at the sediment-water interface, where nitrate and antibiotics need to diffuse through the overlying water. However, the antibiotics' effect on sedimentary N removal and associated N 2 O production has not been adequately investigated under in situ conditions. Here, isotope pairing techniques, including slurry incubations (potential) and intact core incubations (in situ), combined with metagenomic analysis were applied to investigate the impacts of two protein-inhibiting antibiotics (oxytetracycline and thiamphenicol) on sediment nitrogen removal in a subtropical estuary. Slurry incubations showed that the two antibiotics significantly inhibited denitrification (67–98%) and anammox (49–99%), while intact core incubations presented no antibiotic effect at upstream but significant inhibition (23%-52%) at downstream. Meanwhile, N 2 O yields were stimulated up to 20 folds in slurry incubations yet showing insignificant response in intact cores. Such contrasting results between up- and down-stream and between slurry and intact core incubations strongly indicated that permeability, which determines diffusion of antibiotics to microbes, is the key to exert the effect of antibiotics on in situ sedimentary nitrogen removal processes regardless the existence of antibiotics resistance genes. This diffusive obstruction may mitigate the toxic effect of antibiotics on nitrogen removal related microbes in natural environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Accelerated solvent extraction was investigated as a novel alternative technology for the separation and quantitative analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine from poultry eggs, and the results were compared with the results of liquid–liquid extraction. Rapid quantification of the target compounds was carried out by ultra‐performance liquid chromatography‐electrospray ionization tandem triple quadrupole mass spectrometry. This optimized method was validated according to the requirements defined by the European Union and the United States Food and Drug Administration. Finally, the new approach was successfully applied to the quantitative determination of these analytes in 90 commercial poultry eggs from local supermarkets. [ABSTRACT FROM AUTHOR]

Abstract Sensitive and selective thin layer chromatographic methods have been developed for the analysis of three veterinary drugs. The first one is the determination of Amprolium HCL (AMP) and Ethopabate (ETHOP) in a mixture and in the presence of their degradation products. It was carried out on a TLC plates, silica gel 60 F 254 using acetonitrile-methanol-ammonium acetate buffer at pH 8.2 in the ratio 2:3:0.5 (v/v/v) as mobile phase. Quantification was carried out with UV detection at 274 nm and 272 nm for AMP and ETHOP, respectively. Forced degradation studies were performed using 4 M NaOH. The second one is the determination of Florfenicol (FLO) in presence of its related impurities Chlormphenicol (CLO) and Thiamphenicol (TIO). The analysis was carried out on a HPTLC plates, silica gel 60 F 254 using chloroform-methanol-formic acid in the ratio 9:1:0.1 (v/v/v). Quantification was carried out with UV detection at 226 nm for FLO. Linearity ranges, mean recovery and relative standard deviation were calculated. The methods have been successfully applied for the determination of the cited drugs in bulk powder and in pharmaceutical formulations. The results obtained were statistically in full agreement when compared with a reported method. Highlights • Sensitive and selective TLC methods have been developed for the analysis of three veterinary drugs (AMP, ETHOP & FLO). • First elucidation of the structures of the degradation products of the studied drugs. • High throughput method where analysis of several mixture can be analyzed in a parallel manner rather than sequential as HPLC. • Selective determination of cited drugs without interference from excipients, degradation products or related impurities. [ABSTRACT FROM AUTHOR]

Florfenicol, a structural analog of thiamphenicol, has broad‐spectrum antibacterial activity against gram‐negative and gram‐positive bacteria. This study was conducted to investigate the epidemiological, pharmacokinetic–pharmacodynamic cutoff, and the optimal scheme of florfenicol against Escherichia coli (E. coli) with PK‐PD integrated model in the target infectious tissue. 220 E. coli strains were selected to detect the susceptibility to florfenicol, and a virulent strain P190, whose minimum inhibitory concentration (MIC) was similar to the MIC50 (8 μg/ml), was analyzed for PD study in LB and ileum fluid. The MIC of P190 in the ileum fluid was 0.25 times lower than LB. The ratios of MBC/MIC were four both in the ileum and LB. The characteristics of time‐killing curves also coincided with the MBC determination. The recommended dosages (30 mg/kg·body weight) were orally administrated in healthy pigs, and both plasma and ileum fluid were collected for PK study. The main pharmacokinetics (PK) parameters including AUC24 hr, AUC0–∞, Tmax, T1/2, Cmax, CLb, and Ke were 49.83, 52.33 μg*h/ml, 1.32, 10.58 hr, 9.12 μg/ml, 0.50 L/hr*kg, 0.24 hr−1 and 134.45, 138.71 μg*hr/ml, 2.05, 13.01 hr, 16.57 μg/ml, 0.18 L/hr*kg, 0.14 hr−1 in the serum and ileum fluid, respectively. The optimum doses for bacteriostatic, bactericidal, and elimination activities were 29.81, 34.88, and 36.52 mg/kg for 50% target and 33.95, 39.79, and 42.55 mg/kg for 90% target, respectively. The final sensitive breakpoint was defined as 16 μg/ml. The current data presented provide the optimal regimens (39.79 mg/kg) and susceptible breakpoint (16 μg/ml) for clinical use, but these predicted data should be validated in the clinical practice. [ABSTRACT FROM AUTHOR]

Objectives: To identify major facilitator superfamily (MFS)-type chloramphenicol transporters of Acinetobacter baumannii AYE, to characterize its substrate specificity and identify CraA substrate and H+ binding sites.Methods: Five ORFs predicted to encode chloramphenicol transporters were heterologously expressed in Escherichia coli and their substrate specificity was determined by drug susceptibility assays on solid agar medium. CraA transport properties were determined via whole cell fluorescence experiments using ethidium and dequalinium. ACMA quenching was used to characterize the H+/drug antiport process in everted membrane vesicles. The function of CraA in A. baumannii was determined by drug susceptibility assay using A. baumannii ATCC 19606 ΔcraA.Results: CraA, ABAYE0913 and CmlA5 are functionally active when overproduced in E. coli. ABAYE0913 conferred resistance to florfenicol and benzalkonium, CmlA5 conferred resistance to chloramphenicol and thiamphenicol, and craA expression resulted in resistance to chloramphenicol, thiamphenicol, florfenicol, ethidium, dequalinium, chlorhexidine, benzalkonium, mitomycin C and TPP+. Cell expressing craA_E38A showed no resistance to all tested drugs, implying that Glu-38 is involved in the binding of drugs and/or protons. Functional assays indicated that substitution of Asp-46 to Ala resulted in severe susceptibility to cationic drugs, chloramphenicol and thiamphenicol. In contrast, Glu-338 is important for the recognition of chloramphenicol, florfenicol, chlorhexidine and dequalinium.Conclusions: This study suggests that CraA has a broad substrate specificity, similar to that of E. coli MdfA. However, due to the presence of three charged residues in the transmembrane region conferring different susceptibility profiles upon substitution to Ala, we postulate that CraA has a different substrate recognition mode compared with MdfA. [ABSTRACT FROM AUTHOR]

Phenicol antibiotics, such as chloramphenicol, thiamphenicol, and florfenicol, are commonly used in the veterinary and aquaculture fields to treat diseases and have frequently been detected in aquatic environments. Nevertheless, there is limited information regarding the effects of phenicol antibiotics on aquatic nontarget species. Thus, the present study aims to investigate the long‐term (21‐d) influence on the reproduction and growth of and the acute (24‐h) oxidative response and tissue damage in the crustacean Daphnia magna after exposure to phenicol drugs, including their environmental concentrations. The results indicate that D. magna exposed to florfenicol are likely to cause more adverse effects than those exposed to chloramphenicol and thiamphenicol over long‐term (21‐d) exposures. Furthermore, changes in biochemical biomarkers such as malondialdehyde (MDA), catalase (CAT), and reduced glutathione (GSH) induced by individual and mixtures of phenicol antibiotics were also observed. Low concentrations of chloramphenicol, thiamphenicol + florfenicol, and chloramphenicol + thiamphenicol significantly increased the MDA levels of D. magna after 24‐h exposures, causing cellular oxidative damage in the animals. In addition, discrepancies between CAT activities and GSH levels were observed, underscoring the need to evaluate multiple indicators of oxidative stress in toxicological studies using D. magna as a model. Environ Toxicol Chem 2019;38:575–584. © 2018 SETAC [ABSTRACT FROM AUTHOR]

Abstract A reliable liquid chromatography-tandem mass spectrometry method was developed to determine total florfenicol residues in bovine tissues and eel. Florfenicol and its metabolites (florfenicol amine, monochloroflorfenicol, florfenicol oxamic acid, and florfenicol alcohol) were analyzed as the marker residue, florfenicol amine, as defined by several regulatory agencies. After hydrolysis with hydrochloric acid, samples were defatted and subjected to solid-supported liquid extraction and Oasis MCX-cartridge cleanup before analysis. The method was validated for florfenicol and its metabolites at two levels in eel and bovine muscle, fat, and liver. Excellent recoveries were obtained (93–104%), with relative standard deviations of <6% for all compounds. Negligible matrix effects and minimal analyte loss during sample preparation enabled accurate quantification by external calibration using solvent standards. No interfering peaks were observed around the retention time of florfenicol amine, indicating the high selectivity of the method. Retention times in the spiked samples corresponding to that of the calibration standard in solvent did not exceed ±0.1 min. Ion ratios from the spiked sample were within ±10% (relative) of the calibration standards. Calibration curves were linear in the range of 0.5 to 100 ng/mL, with coefficients of determination higher than 0.998. The limits of quantification and limits of detection of the proposed method were estimated to be 0.01 mg/kg and 0.0005 mg/kg, respectively, in all food samples. Thus, the developed method is considered reliable and suitable for regulatory use. Highlights • An LC-MS/MS method was developed for total florfenicol residues in foods. • Florfenicol and its metabolites were analyzed as the marker, florfenicol amine. • Sample hydrolysis, cleanup, and LC-MS/MS conditions were optimized. • The proposed method demonstrated excellent recoveries and precision. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Quantitative reactivity scale of sulfur model compounds. • Kinetic modeling of inhibiting effect. • Competitive adsorption between sulfur reactants. • Adsorption constant of BT higher than that of 2MT. Abstract The transformation of various model sulfur compounds (2-methylthiophene: 2MT, 3-methylthiophene: 3MT and benzothiophene: BT) representative of sulfur compounds in FCC gasoline was investigated over a CoMoS/Al2O3 catalyst. More specifically, a quantitative reactivity scale was established with BT being more reactive than 3MT and 2MT. In mixture, their reactivity was reduced due to the presence of the other sulfur compound, the scale of reactivity being preserved. BT strongly inhibits the transformation of 2MT. With a single kinetic model based on a Langmuir Hinshelwood formalism, kinetic and adsorption parameters were calculated and the results explained by mutual competitive adsorption between 2MT and BT with a higher adsorption constant for BT compared to that of 2MT. [ABSTRACT FROM AUTHOR]

The pharmacokinetics of florfenicol (FF) and thiamphenicol (TP) after single intravenous (IV) and oral (PO) administration was investigated in Mulard ducks. Both antibiotics were administered at a dose of 30 mg/kg body weight, and their concentrations in plasma samples were assayed using high‐performance liquid chromatography with ultraviolet detection. Pharmacokinetic parameters were calculated using a noncompartmental method. After IV administration, significant differences were found for the mean residence time (2.25 ± 0.21 hr vs. 2.83 ± 0.50 hr for FF and TP, respectively) and the general half‐life (1.56 ± 0.15 hr vs. 1.96 ± 0.35 hr for FF and TP, respectively) indicating slightly slower elimination of TP as compared to FF. The clearance, however, was comparable (0.30 ± 0.07 L/hr/kg for FF and 0.26 ± 0.04 L/hr/kg for TP). The mean volume of distribution was below 0.7 L/kg for both drugs. Pharmacokinetics after PO administration was very similar for FF and TP suggesting minor clinical importance of the differences found in the IV study. Both antimicrobials showed rapid absorption and bioavailability of more than 70% indicating that PO route should be an efficient method of FF and TP administration to ducks under field conditions. [ABSTRACT FROM AUTHOR]

A widely applicable method involving liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (LC-ESI/MS/MS) was developed for the simultaneous determination of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in eggs. Samples were extracted with ethyl acetate-acetonitrile-ammonium hydroxide (49:49:2, v/v) and defatted with hexane saturated with acetonitrile. The analysis was carried out on a mass spectrometer via an electrospray interface operated in the positive and negative ionization modes using deuterated chloramphenicol-d5 as the internal standard. The limits of detection and limits of quantification were 0.04–0.5 μg/kg and 0.1–1.5 μg/kg in eggs, respectively. The average recoveries of the four analytes from egg samples were 90.84–108.23%, with relative standard deviations of less than 9.61%. The corresponding intra-day and inter-day variations were found to be less than 8.11% and 11.30%, respectively. Finally, the new approach was successfully applied to the quantitative determination of these analytes in 50 commercial eggs from local supermarkets. [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to determine phenotypic and genotypic resistance, virulence and clonal relationship of aeromonads and related species isolated from Czech carp fisheries. Methods and Results: Forty‐nine isolates obtained from a total of 154 fish from three breeding facilities were species identified using matrix‐assisted laser desorption/ionization time of flight and the sequencing of the rpoB housekeeping gene. Most Aeromonas isolates were identified as Aeromonas veronii (94%, n = 34). Susceptibility to six antibiotics (oxytetracycline, flumequine, florfenicol, sulphamethoxazole/trimethoprim, enrofloxacin and oxolinic acid) was tested using the disc diffusion method. The presence of resistance genes and virulence factors was verified by PCR and sequencing, and the clonal relationship was analysed using pulsed‐field gel electrophoresis (PFGE). Phenotypic resistance to one or more antimicrobials was found in 32 isolates (65%, n = 49). Resistance to oxytetracycline was the most common (41%) and associated mainly with the presence of tet(E) gene, while the percentage of isolates resistant to florfenicol was low (2%). Isolates carried one to five of the tested virulence factors and showed high diversity of PFGE profiles. Conclusions: Since the highest percentage of antimicrobial resistance in aeromonads was found for oxytetracycline and the lowest percentage for florfenicol, it is suggested that florfenicol could be an adequate treatment alternative in carp fisheries. Significance and Impact of the Study: Increasing resistance of aeromonads to commonly used antimicrobials has become an emerging problem in fisheries. This study was conducted in relation to the practical needs to identify a suitable antibiotic as an alternative to oxytetracycline. [ABSTRACT FROM AUTHOR]

Aim: To assess the effect of antibiotics administered in feed on the resistance phenotypes and genotypes of Escherichia coli in the chicken intestine. Method and Results: Chickens were administered amoxicillin, chlortetracycline and florfenicol in feed and 203 intestinal E. coli were examined for their susceptibility to 11 antimicrobial agents and for the presence of antibiotic resistance genes (ARG) using PCR. DNA was extracted from chicken stool samples in 15, 20, 30 and 40 day old chickens. We found that while antibiotic resistance rates increased with time, the relative gene abundance of tet(W), tet(A), cmlA, cfr and sul1 decreased. In contrast, the relative abundance of gene blaTEM and mcr‐1 increased over the experimental period. Pearson correlation analysis indicated that sul1 was correlated with tet(W) (R = 0·630, P < 0·01) and cmlA was correlated with cfr (R = 0·587, P < 0·01). Interestingly, mcr‐1 correlated with tet(W) (R = −0·546, P < 0·05). Conclusions: Administration of different antibiotic reduced the relative abundance of ARG in chickens but did not halt the expansion of antibiotic resistance. Significance and Impact of the Study: Changing the pattern of antibiotic types used to prevent antibiotic resistance in chickens is not a viable method to prevent the spread of ARG. [ABSTRACT FROM AUTHOR]

An ultrasensitive monoclonal antibody-based gold nanoparticle immunochromatographic strip assay and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) were developed to detect florfenicol (FF) and thiamphenicol (TAP) in egg samples. The ic-ELISA, with optimized pH, methanol content and sodium chloride content, exhibited an IC50 value of 0.2 ng/mL for FF and 0.27 ng/mL for TAP, with the working range of 0.05-0.77 and 0.05-1.42 ng/mL, respectively. The optimized ic-ELISA showed negligible cross-reactivity with other phenols and broad-spectrum antibiotics. The recoveries in egg samples using the ic-ELISA ranged from 84% to 115% with a coefficient of variation of less than 5%. Based on this monoclonal antibody, a rapid and ultrasensitive immunochromatographic strip assay was developed with a cutoff value of 1 ng/mL for FF and TAP. Our results indicated that both developed methods were highly useful for screening FF and TAP in eggs. [ABSTRACT FROM AUTHOR]

A competitive lateral flow immunoassay (LFA) using fluorescent microspheres (FMs) as label was developed for the quantitative detection of chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF) in milk. The limit of detection (LOD) for CAP, TAP and FF in milk was 0.08, 0.8 and 1.9 μg L−1, respectively. The recovery of intra and inter-assay ranged from 87.7% to 107.0% and 82.5% to 112.3%, with corresponding coefficient of variations less than 11.3% and 14.5%, respectively. The sensitivity of the FMs lateral flow assay (FMs-LFA) was comparable to those of the colloidal gold lateral flow assay. A quantitative comparison of the FMs-LFA and LC-MS/MS analysis of milk samples indicated good agreement between the two methods. The FMs-LFA can be used as a reliable, rapid and cost-effective method for food safety analysis. [ABSTRACT FROM AUTHOR]

A quantitative method for analysis of amphenicols (chloramphenicol – CAP, thiamphenicol – TAP and florfenicol – FF) in Nile tilapia using LC–MS/MS is described. A simple sample preparation procedure was optimized using a Plackett-Burman design. The method was validated in accordance with Decision 2002/657/EC. Repeatability and reproducibility were less than 10.7% and 16%, respectively, for all compounds. Recoveries varied from 79.8% to 92.0%. CCα was 0.019, 54.81 and 54.93 μg.kg −1 for CAP, FF and TAP, respectively. CCβ was 0.068, 64.88 and 58.91 μg.kg −1 for CAP, FF and TAP, respectively. Limits of quantification (LOQ) were 12.5 μg.kg −1 for FF and TAP and 0.15 μg.kg −1 for CAP. Nile tilapia fillets (n = 32) analyzed did not contain chloramphenicol. Thiamphenicol was detected in one sample (3.1%) and florfenicol was detected in every sample, all of them at concentrations below the maximum residue limit. [ABSTRACT FROM AUTHOR]

Antimicrobial residues might persist in products and by-products destined for human or animal consumption. Studies exploring the depletion behavior of florfenicol residues in broiler chicken claws are scarce, even though claws can enter the food chain directly or indirectly. Hence, this study intended to assess the concentrations of florfenicol (FF) and florfenicol amine (FFA)--its active metabolite--in chicken claws from birds that were treated with a therapeutic dose of florfenicol. Furthermore, concentrations of these analytes in this matrix were compared with their concentrations in edible tissues at each sampling point. A group of 70 broiler chickens were raised under controlled conditions and used to assess residue depletion. Sampling points were on days 5, 10, 20, 25, 30, 35, and 40 after ceasing treatment, thus extending beyond the withdrawal period established for muscle tissue (30 days). Analytes were extracted using HPLC-grade water and acetone, and dichloromethane was used for the clean-up stage. Liquid chromatography coupled to mass spectroscopy detection (LC-MS/MS) was used to detect and quantify the analytes. The analytical methodology developed in this study was validated in-house and based on the recommendations described in the Commission Decision 2002/657/EC from the European Union. Analyte concentrations were calculated by linear regression analysis of calibration curves that were fortified using an internal standard of chloramphenicol-d5 (CAF-d5). The depletion time of FF and FFA was set at 74 days in claws, based on a 95% confidence level and using the limit of detection (LOD) as the cut-off point. Our findings show that FF and FFA can be found in chicken claws at higher concentrations than in muscle and liver samples at each sampling point. [ABSTRACT FROM AUTHOR]

A magnetic surface molecularly imprinted polymers (MMIPs) with thiamphenicol (TAP) specificity was prepared by using thiamphenicol as a template molecule, methacrylic acid (MAA) as the functional monomer, and silicon dioxide-coated ferriferous oxide (Fe3O4 @ SiO2) as the magnetic carrier. The composition, thermal stability, and magnetic properties of the polymer were characterized by fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and vibration sample magnetometer (VSM). The results of these studies show that the imprinted polymer layer was successfully applied to the surface of the Fe3O4@SiO2 magnetic material, and that the imprinted particles retain desirable magnetic properties. The MMIPs were applied to extract and quantify thiamphenicol in milk samples. The specific recognition capability of the polymers was affirmed by high performance liquid chromatographic (HPLC) analysis, establishing the limit of detection (LOD) as 10 µg/L and a recovery rate of greater than 85%. A rapid and selective method was established to quantify TAP using MMIPs as a sorbent. The method was used to detect thiamphenicol in milk samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A simple, reliable and sensitive liquid chromatography-tandem mass spectrometry-based confirmatory method was redeveloped and validated for the simultaneous determination of chloramphenicol, thiamphenicol, florfenicol and florfenicol amine in chicken muscles. The analytes were extracted from minced chicken muscle with acetonitrile and ammoniated water mixture. A second extraction with ethyl acetate was followed by evaporation and dissolution of the residue in ammoniated methanol before defatting with n-hexane. Finally, the extract was further cleaned up by dispersive solid phase extraction using C-18 end-capped dispersive material. The validation protocol was adapted from the European Commission Decision 2002/657/EC and all the performance characteristics were successfully satisfied. The recoveries of all the analytes were found to be in the range of 86.4-108.1% and the precision values, within day and between days, ranged from 2.7% to 11% and 4.4% to 16.3%, respectively. The method was tested in various incurred samples and applied to analyse a wide range of random poultry market samples (n = 120) collected from three cities of the Punjab, Pakistan. Chloramphenicol and florfenicol residues were detected at low levels in less than 11% of the samples. Chloramphenicol was detected only in 4 samples with the concentration range of 0.17-0.477 µg kg-1, whereas the levels of florfenicol/florfenicol amine residues detected in 9 samples ranged from 8.7 to 32.8 µg kg-1. Moreover, most of the florfenicol residues were identified as tissue bound, extractable only after strong acid hydrolysis. [ABSTRACT FROM AUTHOR]

An environmentally friendly nitrogen-sulfur-doped carbon quantum dots molecularly imprinted fluorescent probe (N,S-CDs@MIP) was prepared for the detection of thiamphenicol (TAP) in animal-derived foods. The N,S-CDs, the core fluorophores in optical sensors, were synthesized from food waste of crayfish shells and l -cysteine and assembled to molecularly imprinted layers by Si–O–Si bond. The fluorescence produced by the novel probe in response to TAP ranged from 10.00 to 300.0 μg/L, with a detection limit of 6.20 μg/L. The developed method was also successfully applied to real milk, fish and tap water with 92.08–108.4% recoveries, which agrees with the high-performance liquid chromatography (HPLC) analysis (89.15%–110.7%). The developed probe is cheap with a short detection time (30 min) and provides a theoretical and practical operation basis for monitoring TAP residue levels. [Display omitted] • It is the first time to synthesize N,S-CDs@MIPs for detecting TAP residual in animal derived foods. • Shorter detection time towards TAP sensing within 30 min. • Recycling food waste as raw material for an environmentally friendly purpose. • The fluorophore and molecularly imprinted layer were simply assembled by Si–O–Si bond. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sensitive and rapid method for the simultaneous determination of three amphenicol antibiotic (chloramphenicol, thiamphenicol and florfenicol) residues in aquaculture products was developed using UPLC-MS/MS. • A modified QuEChERS method was optimized using single-factor experiments and response surface methodology. • Mean recoveries of chloramphenicol, thiamphenicol and florfenicol in 12 types of aquaculture products ranged from 78.6% to 106.2% with RSDs less than 12.1%. • The limit of quantification of chloramphenicol, thiamphenicol and florfenicol were 0.01–0.04 μg/kg. A simple and sensitive method for the determination of amphenicol antibiotic (chloramphenicol, thiamphenicol and florfenicol) residues in aquaculture products was developed based on a response surface methodology-modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The pretreatment method was optimized via single-factor experiments and response surface methodology based on central-composite design to maximize the extraction efficiency and purification effect. The results show that chloramphenicol, thiamphenicol and florfenicol had good linearity in the range of 0.1–50 ng/mL. The recoveries of these amphenicol antibiotics in 12 types of aquaculture products ranged from 78.6% to 106.2% with relative standard deviations less than 12.1%. The method had high sensitivity with the limit of quantification of analytes being 0.01–0.04 μg/kg. Finally, the developed method was used to analyze actual samples. The results show that this method has good application potential for detecting residues of amphenicol antibiotics in aquaculture products. [ABSTRACT FROM AUTHOR]