RESUMEN
The multiple-readout capability of multimodal detection enhances the flexibility, reliability, and accuracy of lateral flow immunoassay (LFIA). The conjugation of two different metal-organic frameworks (MOFs) as a new-generation composite material offers extraordinary opportunities for developing multimodal LFIA. It is anticipated to compensate limitations of traditional single colorimetric signal LFIA and improve the analysis performance. Herein, an ultra-bright fluorescent AIE-MOF was proposed and coupled with an in-situ growth of Prussian blue (PB) nanoparticles strategy to obtain a novel multimodal signal tracer (AIE-MOF@PB). Thereafter, it was successfully applied to develop the multimodal LFIA platform for the detection of nitrofurazone metabolites. The synergy of AIE-MOF and PB endows AIE-MOF@PB with superb water dispersibility, robust fluorescence emission, brilliant colorimetric signal, marvelous photothermal conversion, and enhanced antibody coupling efficiency, all of which facilitate a highly sensitive triple-readout LFIA platform. The detection sensitivity improved by at least 5-fold compared with the colloidal gold-based LFIA. This work not only inspires the rational design of aggregation-induced emission luminogens (AIEgen)-based complex materials but also highlights the promising potential in flexible point-of-care applications.
Asunto(s)
Técnicas Biosensibles , Límite de Detección , Estructuras Metalorgánicas , Nitrofurazona , Estructuras Metalorgánicas/química , Inmunoensayo/métodos , Inmunoensayo/instrumentación , Técnicas Biosensibles/métodos , Nitrofurazona/análisis , Nitrofurazona/química , Humanos , Ferrocianuros/química , Colorimetría/métodos , Colorantes Fluorescentes/químicaRESUMEN
BACKGROUND: Nitrofurazone (NFZ) is a widely-used antimicrobial agent in aquaculture. The NFZ residue can be transmitted to humans through the food chain, and cause adverse health effects including carcinogenesis and teratogenesis. Until now, a number of modified electrodes have been developed for NFZ detection, however, there are some issues that need to be improved. For example, the reported detection sensitivity is relatively low, the modification procedure is complicated, and conventional three-electrode system is used. Therefore, it is quite important to develop new NFZ detection method with higher sensitivity, simplicity and practicality. RESULTS: Herein, a kind of integrated three-electrode array consisted with porous graphene is easily prepared through laser engraving of commercial polyimide tape. Five kinds of graphene arrays were prepared at different laser power percentage (i.e. 30 %, 40 %, 50 %, 60 % and 70 %). It is found that their structure, morphology, fluffiness and porosity show great difference, consequently affecting the electrochemical performance of graphene arrays such as conductivity, active area and electron transfer ability. The engraved graphene array at 50 % laser power percentage (LIG-50 array) is superior owing to uniform 3D structure, abundant pores and high stability. More importantly, LIG-50 array is more active for NFZ oxidation, and significantly enhances the detection sensitivity. The linear range of LIG-50 sensor is from 0.2 to 8 µM, and the detection limit is 0.035 µM, which is successfully used in fish meat samples. SIGNIFICANCE: A sensitive, portable and practical electrochemical sensor has been successfully developed for NFZ using laser-engraved graphene array. The demonstration using fish meat samples manifests this new sensor has good accuracy and great potential in application. This study could provide a new possibility for the design and fabrication of other high-performance electrochemical sensor for various applications in the future.
Asunto(s)
Técnicas Electroquímicas , Electrodos , Grafito , Rayos Láser , Nitrofurazona , Nitrofurazona/análisis , Grafito/química , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Límite de Detección , AnimalesRESUMEN
The study presents the successful development of a new electrochemical sensor with low cost and disposability for application in nitrofurazone detection in environmental and pharmaceutical samples. The sensors were fabricated using materials obtained from local storage and conductive carbon ink. The modification of the screen-printed electrodes with the hybrid nanomaterial based on silver nanoparticles, carbon quantum dots, and carbon nanotubes showed synergistic contributions in the nitrofurazone electrooxidation, as observed in the wide linear range (0.008 at 15.051 µM), with a sensitivity of 0.650 µA/µM. The limit of detection obtained was 4.6 nM. Differential pulse voltammetry, cyclic voltammetry, X-ray photoelectron spectroscopy, X-ray diffraction analysis, and high-resolution transmission electron microscopy were used to evaluate the electrochemical and structural characteristics. Studies of possible interferences were considered with nitrofurazone in the presence of the ions and organic molecules. The results were satisfactory, with a variation of 93.3% ± 4.39% at 100% ± 2.40%. The low volume used in the analyses (50 µL), disposability, high sensibility, selectivity, and low limit of detection are advantages that make the proposed sensor an electrochemical tool of high viability for the NFZ detection in environmental matrices and pharmaceutical formulations.
Asunto(s)
Antibacterianos , Técnicas Electroquímicas , Nanopartículas del Metal , Nanotubos de Carbono , Nitrofurazona , Nitrofurazona/análisis , Nitrofurazona/química , Técnicas Electroquímicas/métodos , Nanotubos de Carbono/química , Nanopartículas del Metal/química , Antibacterianos/análisis , Límite de Detección , Plata/química , Electrodos , Puntos Cuánticos/químicaRESUMEN
The synthesis of three-dimensional silver nanopopcorns (Ag NPCs) onto a flexible polycarbonate membrane (PCM) for the detection of nitrofurazone (NFZ) on the fish surface by surface-enhanced Raman spectroscopy (SERS) is presented. The proposed flexible Ag-NPCs/PCM SERS substrate exhibits significant Raman signal intensity enhancement with the measured enhancement factor of 2.36 × 106. This is primarily attributed to the hotspots created on Ag NPCs, including numerous nanoscale protrusions and internal crevices distributed across the surface of Ag NPCs. The detection of NFZ by this flexible SERS substrate demonstrates a low limit of detection (LOD) of 3.7 × 10-9 M and uniform and reproducible Raman signal intensities with a relative standard deviation below 8.34%. It also exhibits excellent stability, retaining 70% of its efficacy even after 10 days of storage. Notably, the practical detection of NFZ in tap water, honey water, and fish surfaces achieves LOD values of 1.35 × 10-8 M, 5.76 × 10-7 M, and 3.61 × 10-8 M, respectively, which highlights its effectiveness across different sample types. The developed Ag-NPCs/PCM SERS substrate presents promising potential for sensitive SERS detection of toxic substances in real-world samples.
Asunto(s)
Límite de Detección , Nanopartículas del Metal , Nitrofurazona , Plata , Espectrometría Raman , Espectrometría Raman/métodos , Plata/química , Nitrofurazona/análisis , Nitrofurazona/química , Nanopartículas del Metal/química , Animales , Peces , Miel/análisis , Agua Potable/análisis , Cemento de Policarboxilato/química , Membranas Artificiales , Contaminantes Químicos del Agua/análisis , Propiedades de Superficie , Contaminación de Alimentos/análisisRESUMEN
Periphytic protists including ciliates are the primary components of microbial communities in which they play a vital role in the progression of food webs by moving resources from lower to higher trophic levels. However, the toxic effects of veterinary antibiotics on periphytic protists across four seasons are minimally understood. Therefore, in this study, a 1-year survey was conducted with the antibiotic nitrofurazone (NFZ) applied at concentrations of 0.0, 1.5, 3.0, 6.0, and 12.0 mg/L. Samples of protist communities were collected using microscope glass slides during four seasons in the coastal waters of the Yellow Sea, Qingdao, northern China. The abundance of protists dropped with an increase in NFZ concentrations, and almost all species were dead at a concentration of 12.0 mg/L. The 12 h-LC50 values of NFZ for the protist biota were similar among the four seasons, despite significant seasonal variability in the community structure. The present results suggest that the periphytic protist biota may be used as a biomarker for assessing the ecotoxicity of NFZ in marine environments regardless of the year season.
Asunto(s)
Cilióforos , Nitrofurazona , Estaciones del Año , Nitrofurazona/farmacología , Cilióforos/efectos de los fármacos , China , Contaminantes Químicos del Agua/toxicidad , Antibacterianos/farmacología , Agua de MarRESUMEN
Semicarbazide (SEM), a marker residue used to monitor the use of prohibited drug nitrofurazone (NFZ), is commonly found in wild crustaceans, implying the natural origin. However, the difference between endogenous and exogenous SEM has rarely been investigated. So, tissue-bound SEM was determined in samples collected from giant river prawns cultured in an aquaculture farm and in samples from an experiment where giant river prawns were fed twice a day with NFZ at 30â¯mg/kg for 5 days. At day 10 of drug withdrawal, muscle SEM of the NFZ-fed prawn was 17.78â¯ng/g and depleted to 1.18â¯ng/g at day 90 (half-life 20.31 days) which was significantly higher than the control prawn (usually ≤ 0.1â¯ng/g). In contrast, the average SEM in the shell was independent of NFZ treatment. SEM was not found in the aquaculture farm samples, implying that the SEM in cultured prawn did not originate from SEM contamination.
Asunto(s)
Palaemonidae , Penaeidae , Semicarbacidas , Animales , Nitrofurazona , Administración Oral , AcuiculturaRESUMEN
Background: Leishmaniasis, caused by the protozoan Leishmania sp., infects phagocyte cells present in lymphatic organs. This study demonstrates the influence of nanostructured lipid carrier-loaded hydroxymethylnitrofurazone (NLC-NFOH) on lymphatic uptake using a chylomicron-blocking flow model in rats. Method: Lymphatic uptake of NFOH was assessed 1 h after oral administration of dimethyl sulfoxide with NFOH or NLC-NFOH with and without cycloheximide pretreatment. Result: Dimethyl sulfoxide with NFOH and NLC-NFOH showed NFOH serum concentrations of 0.0316 and 0.0291 µg/ml, respectively. After chylomicron blocking, NFOH was not detected. Conclusion: Despite log P below 5, NFOH was successfully taken up by the lymphatic system. Long-chain fatty acids and particle size might be main factors in these findings. NLC-NFOH is a promising and convenient platform for treating leishmaniasis via oral administration.
Asunto(s)
Leishmaniasis , Nanoestructuras , Nitrofurazona/análogos & derivados , Ratas , Animales , Dimetilsulfóxido , Quilomicrones , Administración Oral , Portadores de Fármacos , Tamaño de la PartículaRESUMEN
In this work, an ultra-sensitive lateral flow immunoassay (LFIA) with SERS/colorimetric dual signal mode was constructed for the detection of nitrofurazone metabolites, an antibiotic prohibited in animal-origin foods. Au@4-MBN@AgNRs nano-sandwich structural signal tag integrates the unique advantages of high signal-to-background ratio and anti-matrix interference through geometric control of SERS tag and nanoengineering adjustment of chemical composition. Under the optimal conditions, the detection limits of nitrofurazone metabolites by SERS/colorimetric dual-mode LFIA were 20 pg/mL (colorimetric mode) and 0.08 pg/mL (SERS mode). Excitingly, the vLOD of the colorimetric signal improved by a factor of 100 compared to Au NPs-based LFIA. In this study, the proposed dual-mode LFIA was successfully applied to the on-site real-time detection of honey, milk powder, and chicken. It is anticipated that with low background interference and anti-matrix interference output signal, our proposed dual-mode strategy can pave an innovative pathway for the fabrication of a powerful biosensor.
Asunto(s)
Nanopartículas del Metal , Nitrofurazona , Animales , Oro/química , Inmunoensayo , Antibacterianos , Colorimetría , Nanopartículas del Metal/química , Límite de Detección , Espectrometría RamanRESUMEN
Nitrofurazone usage in food-producing animals is prohibited in most countries, including the United States. Regulatory agencies regularly monitor its use in domestic, export/import animals' food products by measuring the semicarbazide (SEM) metabolite as a biomarker of nitrofurazone exposure. However, the use of SEM is controversial because it is also produced in food naturally and thus gives false positive results. A cyano-metabolite, 4-cyano-2-oxobutyraldehyde semicarbazone (COBS), is proposed as an alternate specific marker of nitrofurazone to distinguish nitrofurazone from treated or untreated animals. A synthetic method was developed to produce COBS via metallic hydrogenation of nitrofurazone. The product was isolated and characterized by one- and two-dimensional nuclear magnetic spectroscopy (NMR) experiments, Fourier-transform infrared spectroscopy (FT-IR), and mass spectrometry. The developed synthetic procedure was further extended to synthesize isotopically labeled 4-[13 C]-cyano-2-oxo- [2, 3, 4-13 C3 ]-butyraldehyde semicarbazone. Labeled COBS is useful as an internal standard for its quantification in food-producing animals. Thus, the developed method provides a possibility for its commercial synthesis to procure COBS. This is the first synthesis of the alternate specific marker metabolite of nitrofurazone for possible usage in regulatory analysis to solve a real-world problem.
Asunto(s)
Nitrofurazona , Semicarbazonas , Animales , Nitrofurazona/análisis , Nitrofurazona/metabolismo , Espectroscopía Infrarroja por Transformada de Fourier , Semicarbacidas/análisis , Semicarbacidas/química , Semicarbacidas/metabolismoRESUMEN
The veterinary drug nitrofurazone (5-nitro-2-furaldehyde semicarbazone) exhibits excellent antimicrobial properties but its application in food-producing animals is prohibited. The illegal use of nitrofurazone is regularly monitored by food regulatory agencies. Currently, semicarbazide (SEM) is used as a marker of nitrofurazone exposure. However, the use of SEM as a marker of nitrofurazone is under scrutiny after evidence of a high incidence of false positive tests. To overcome the current dilemma, it is necessary to identify a nitrofurazone-specific marker analyte which requires conducting nitrofurazone metabolism studies in food-producing animals. The use of carbon-14 labeled nitrofurazone would facilitate metabolism studies and structural elucidation of nitrofurazone metabolites of possible utility as a marker compound. In the present work, a synthetic method is described to procure radiolabeled nitrofurazone that incorporates 14 C- carbon at the semicarbazide moiety. The method incorporates 14 C-carbon via employing readily available and more economically affordable [14 C]-urea compared with [14 C]-semicarbazide. To the best of our knowledge, there is no report on the synthesis of 5-nitro-2-furaldehyde [14 C]-semicarbazone from 14 C-urea. The developed method involves monoamination of [14 C]-urea followed by a condensation reaction with 5-nitro-2-furaldehyde to produce 5-nitro-2-furaldehyde [14 C]-semicarbazone in 85% yield with greater than 98% radiochemical purity.
Asunto(s)
Nitrofurazona , Semicarbazonas , Animales , Urea/química , Radioisótopos de CarbonoRESUMEN
Marine periphytic ciliates play a pivotal role in shaping coastal ecosystems dynamics, thereby acting as robust biological indicators of aquatic ecosystem health and functionality. However, the understanding of the effects of veterinary antibiotics on composition and structure of periphytic ciliate communities remains limited. Therefore, this research investigates the influence of the veterinary antibiotic nitrofurazone on the community dynamics of marine periphytic ciliates through bioassay experiments conducted over a one-year cycle. Various concentrations of nitrofurazone were administered to the tested ciliate assemblages, and subsequent changes in community composition, abundance, and diversity were quantitatively analyzed. The research revealed significant alterations in periphytic ciliate communities following exposure to nitrofurazone. Concentration-dependent (0-8 mg L-1) decrease in ciliates abundance, accompanied by shifts in species composition, community structure, and community patterns were observed. Comprehensive assessment of diversity metrics indicated significant changes in species richness and evenness in the presence of nitrofurazone, potentially disrupting the stability of ciliate communities. Furthermore, nitrofurazone significantly influenced the community structure of ciliates in all seasons (winter: R2 = 0.489; spring: R2 = 0.666; summer: R2 = 0.700, autumn: R2 = 0.450), with high toxic potential in treatments 4 and 8 mg L-1. Differential abundances of ciliates varied across seasons and nitrofurazone treatments, some orders like Pleurostomatida were consistently affected, while others (i.e., Strombidida and Philasterida) showed irregular distributions or were evenly affected (e.g., Urostylida and Synhymeniida). Retrieved contrasting patterns between nitrofurazone and community responses underscore the broad response repertoire exhibited by ciliates to antibiotic exposure, suggesting potential cascading effects on associated ecological processes in the periphyton community. These findings significantly enhance the understanding of the ecological impacts of nitrofurazone on marine periphytic ciliate communities, emphasizing the imperative for vigilant monitoring and regulation of veterinary antibiotics to protect marine ecosystem health and biodiversity. Further research is required to explore the long-term effects of nitrofurazone exposure and evaluate potential strategies to reduce the ecological repercussions of antibiotics in aquatic environments, with a particular focus on nitrofurazone.
Asunto(s)
Cilióforos , Ecosistema , Nitrofurazona/toxicidad , Antibacterianos/toxicidad , Monitoreo del Ambiente , BiodiversidadRESUMEN
The efficient removal of organic contaminants from wastewater is, nowadays, a prominent area of study due to its biological as well as environmental significance. Antibiotics are now found in wastewater because of their high use, which has become a source of aquatic pollution. These antibiotics have dangerous implications for people's health. Hence, effective pharmaceutical removal from wastewater and contaminated water bodies, especially the removal of antibiotics, is of major interest to global research organizations. This is why it is necessary to investigate this class of toxic material in wastewater discharge. We synthesized three different coordination polymers (CPs) in the presence of various assistant carboxylate linkers, namely, [Zn(Hbtc)(dip)]n (1), [Zn4(1,2-bdc)4(dip)4]n (2), and [Zn(1,4-bdc)(dip)]n (3) (3,5-di(1H-imidazol-1-yl)pyridine = dip, 1,3,5-benzenetricarboxylic acid = H3btc, 1,2-benzenedicarboxylic acid = 1,2-H2bdc, and 1,4-benzendicarboxylic acid = 1,4-bdc). These CPs were characterized by using different techniques, including single-crystal X-ray diffraction. The structural studies demonstrated that in 2, there are four Zn(II) centers and both centers are in different coordination environments (Zn2 has distorted tetrahedral geometry, whereas Zn1, Zn3, and Zn4 have square pyramidal geometry). Hirshfeld surfaces analysis revealed that different types of intermolecular interactions (Câ¯C, Hâ¯C, Hâ¯H, Oâ¯C, Nâ¯H, and Oâ¯H) are present in the synthesized CPs. We examined the different antibiotics, such as metronidazole (MDZ), nitrofurazone (NFZ), dimetridazole (DTZ), sulfasalazine(SLA), and oxytetracycline (OXY), degradation behaviors of the synthesized CPs, which showed remarkable degradation efficiency. 1 showed photocatalytic behavior toward the NFZ antibiotic in an aqueous media. This study also showed that these catalysts are stable and reusable under mild conditions.
Asunto(s)
Aguas Residuales , Zinc , Humanos , Ligandos , Antibacterianos , Nitrofurazona , Preparaciones FarmacéuticasRESUMEN
A method was established for detecting the content of nitrofurazone (NFZ) by fluorescence quenching of N-Acetyl-L-Cysteine (NAC) coated cadmium telluride quantum dots (CdTe QDs). By means of transmission electron microscopy (TEM) and multispectral methods such as fluorescence and ultraviolet visible spectra (UV-vis), the synthesized CdTe QDs were characterized. The quantum yield (φ) of CdTe QDs was measured as 0.33 by reference method. The CdTe QDs had a better stability, the RSD of fluorescence intensity was 1.51% in three months. NFZ quenching the emission light of CdTe QDs was observed. The analyses of Stern-Volmer and time-resolved fluorescence suggested the quenching was static. The binding constants (Ka) between NFZ and CdTe QDs were 1.14 × 104 (293 K), 0.74 × 104 (303 K) and 0.51 × 104 (313 K) L mol-1. The hydrogen bond or van der Waals force was the dominated binding force between NFZ and CdTe QDs. The interaction was further characterized by UV-vis absorption as well as Fourier transform infrared spectra (FT-IR). Using fluorescence quenching effect, a quantitative determination of NFZ was carried out. The optimal experimental conditions were studied and determined as following: pH was 7 and contact time was 10 min. The effects of reagent addition sequence, temperature and the foreign substances including some metals (Mg2+; Zn2+; Ca2+; K+; Cu2+), glucose, bovine serum albumin (BSA) and furazolidone on the determination were studied. There was a high correlation between the concentration of NFZ (0.40 - 39.63 µg mL-1) and F0/F with the standard curve F0/F = 0.0262c + 0.9910 (r = 0.9994). The detection limit (LOD) reached 0.04 µg mL-1 (3S0/S). The contents of NFZ in beef and bacteriostatic liquid were detected. The recovery of NFZ was 95.13% - 103.03% and RSD was 0.66% - 1.37% (n = 5).
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Compuestos de Cadmio , Puntos Cuánticos , Animales , Bovinos , Puntos Cuánticos/química , Acetilcisteína , Compuestos de Cadmio/química , Fluorescencia , Telurio/química , Nitrofurazona , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría de Fluorescencia/métodosRESUMEN
Nitrofurazone (NFZ) is an antibiotic banned in many countries, as its residue seriously harms the human body. Herein, anti-NFZ aptamers were selected and identified based on the magnetic bead SELEX technique using a ssDNA library with a full length of 90 nucleotides (nt). Five full sequence candidate aptamers (NFZ8, NFZ24, NFZ28, NFZ34, and NFZ70) were obtained by secondary structure analysis. We optimized the entire sequence to obtain a truncated aptamer, a 16 nt sequence (NFZ8-1:5'-GTTCTATTGAAAAAAC-3') that showed the highest affinity for NFZ (Kd = 76.11 nM). The binding site of NFZ and aptamer NFZ8-1 was found to be "GAA" by molecular docking. In addition, utilizing the most special truncated aptamer NFZ8-1 as the identification probe, a graphene oxide fluorescent aptasensor is an innovative for the detection of NFZ residue that showed a wide linear reach from 1.25 to 160 ng/mL and a low limit of detection of 1.13 ng/mL. In the actual water environment sample detection, the recovery rate ranged from 95.21 to 113.66%, and the coefficient of variation ranged from 3.53 to 11.24%. These results demonstrate that the NFZ-truncated aptamer applied to the aptasensor provides a novel methodology for recognizing NFZ residues.
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Aptámeros de Nucleótidos , Nitrofurazona , Humanos , Aptámeros de Nucleótidos/química , Simulación del Acoplamiento Molecular , Técnica SELEX de Producción de Aptámeros , Antibacterianos/análisis , Límite de DetecciónRESUMEN
The use of functional traits of a community as a method to measure its functional dynamics in response to environmental change has gained attention because trait-based approaches offer systematic opportunities to understand the interactions between species diversity and ecosystem function. However, the relationship between functional traits of periphytic protozoa and contamination of aquatic habitats with antibiotics is poorly understood. In this study, we investigated the influence of the antibiotic nitrofurazone on functional traits of marine periphytic protozoan fauna. For this purpose, the protozoan assemblages were collected from coastal waters of the Yellow Sea at Qingdao, northern China, during four seasons of a one-year cycle using glass microscope slides as artificial substrates. The test protozoan communities were then exposed to various treatments of nitrofurazone in laboratory bioassay experiments. Our results demonstrated that the modalities of the functional traits of protozoan communities were generally driven by nitrofurazone toxicity. Briefly, R-mode linked to Q-mode (RLQ) and fourth-corner analyses revealed strong positive correlations between functional traits and nitrofurazone treatments. Trait syndromes in terms of body length, width, weight, height, and size to volume ratios were significantly influenced by nitrofurazone exposure. In particular, small and medium body size species of different feeding types, i.e., algivores, bacterivores, raptors or non-selectives, were more sensitive than other protozoan species to higher concentrations of nitrofurazone. Our findings demonstrate that antibiotic toxicity is likely to affect periphytic protozoan community function, shape the functional processes, and induce toxic responses in the community. The findings of this study suggest that periphytic protozoan communities and their functional traits are suitable bioindicators for evaluating the ecotoxicity of nitrofurazone in marine environments.
Asunto(s)
Cilióforos , Ecosistema , Biodiversidad , Nitrofurazona/toxicidad , Monitoreo del Ambiente/métodos , Antibacterianos/toxicidadRESUMEN
BACKGROUND: Antimicrobial resistance (AMR) is important in equine reproduction, as antimicrobials have historically been widely used in the management of breeding mares. However, evidence of the characteristics of AMR in uterine isolates is limited in the UK. The objective of this retrospective study was therefore to describe temporal changes in AMR patterns of bacteria isolated from the endometrium of Thoroughbred broodmares in south-east England between 2014 and 2020. METHOD: Endometrial swabs were processed for microbiology and antimicrobial susceptibility testing (AST). For frequently isolated bacteria, changes in AMR patterns over time were assessed using a logistic regression model. RESULTS: From 18,996 endometrial swabs, 30.5% were positive for microbial culture. AST was performed on 2091 isolates, representing 1924 swabs collected from 1370 mares located at 132 premises. Beta-haemolytic Streptococcus (BHS, 52.5%) and Escherichia coli (25.8%) were most frequently isolated. In BHS, resistance to enrofloxacin (p = 0.02), nitrofurazone (p < 0.001) and oxytetracycline (p < 0.01) increased significantly between 2014 and 2020, while resistance to trimethoprim-sulfamethoxazole (p < 0.001) decreased. In E. coli, resistance to nitrofurazone increased (p = 0.04) and resistance to gentamycin (p = 0.02) and trimethoprim-sulfamethoxazole (p < 0.001) decreased. LIMITATIONS: Variations in the specimen collection protocols might have affected the frequency of isolates detected. CONCLUSION: Between 2014 and 2020, AMR changed in this bacterial population. However, there was no significant increase in resistance to penicillin (99.6% BHS susceptible), gentamycin (81.7% E. coli susceptible) or ceftiofur.