A non-targeted LC-HRMS approach for detecting exposure to illegal veterinary treatments: The case of cephalosporins in commercial laying Hens

Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Methods for the Quantification of Cefquinome, Ceftiofur, and Desfuroylceftiofuracetamide in Porcine Feces with Emphasis on Analyte Stability

Cefquinome and ceftiofur are β-lactam antibiotics used for the treatment of bacterial infections in swine. Although these antimicrobials are administered intramuscularly, the exposure of the gut microbiota to these cephalosporins is not well described. This exposure can contribute to the emergence and spread of antimicrobials in the environment and to the possible spread of antimicrobial resistance genes. To assess the impact of drug administration on the intestinal excretion of these antimicrobials it is essential to measure the amounts of native compound and metabolites in feces. Two (ultra)-high-performance liquid chromatography-tandem mass spectrometry ((U)HPLC–MS/MS) methods were developed and validated, one for the determination of cefquinome and ceftiofur and the other for the determination of ceftiofur residues, measured as desfuroylceftiofuracetamide, in porcine feces. The matrix-based calibration curve was linear from 5 ng g⁻¹ to 1000 ng g⁻¹ for cefquinome (correlation coefficient (r) = 0.9990 ± 0.0007; goodness of fit (gof) = 3.70 ± 1.43) and ceftiofur (r = 0.9979 ± 0.0009; gof = 5.51 ± 1.14) and quadratic from 30 ng g⁻¹ to 2000 ng g⁻¹ for desfuroylceftiofuracetamide (r = 0.9960 ± 0.0020; gof = 7.31 ± 1.76). The within-day and between-day precision and accuracy fell within the specified ranges. Since β-lactam antibiotics are known to be unstable in feces, additional experiments were conducted to adjust the sampling protocol in order to minimize the impact of the matrix constituents on the stability of the analytes. Immediately after sampling, 500 µL of an 8 µg mL⁻¹ tazobactam solution in water was added to 0.5 g feces, to reduce the degradation in matrix.

Development and applicability of a multi-residue method for dyes, including new residue markers, to detect drug misuse in aquaculture

A qualitative and quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the sensitive and exhaustive analysis of residues from triarylmethane dyes, triarylmethane-derivative dyes, phenothiazines, phenoxazines and xanthenes in aquaculture samples. For a wider and more robust detection of dye misuse on farms, other residue markers were also included the leuco forms of brilliant green, crystal violet and malachite green; one direct metabolite of Victoria pure blue BO and methylene blue and three bile acids, which are endogenous markers of the effects of dye contamination in fish. We optimised the extraction method by comparing several extraction solvents and sample solvents reported in the literature to have the best extraction efficiency. The residues were determined using a positive electrospray ionisation source. We assessed the parameters of this LC-MS/MS method by evaluating the matrix effects, identification and quantitative parameters according to the criteria stipulated in the European Commission Decision No. 2002/657/EC. A study on the applicability of the method was conducted on various aquaculture species and on a positive catfish.

Applying metabolomics to veterinary pharmacology and therapeutics

Metabolomics is the large-scale study of low-molecular-weight substances in a biological system in a given physiological state at a given time point. Metabolomics can be applied to identify predictors of inter-individual variability in drug response, provide clinicians with data useful for decision-making processes in drug selection, and inform about the pharmacokinetics and pharmacodynamics of a drug. It is, therefore, an exceptional approach for gaining new understanding effects in the field of comparative veterinary pharmacology. However, the incorporation of metabolomics into veterinary pharmacology and toxicology is not yet widespread, and this is probably, at least in part, a result of its highly multidisciplinary nature. This article reviews the potential applications of metabolomics in veterinary pharmacology and therapeutics. It integrates key concepts for designing metabolomics studies and analyzing and interpreting metabolomics data, providing solid foundations for applying metabolomics to the study of drugs in all veterinary species.

Antibiotics and Non-Targeted Metabolite Residues Detection as a Comprehensive Approach toward Food Safety in Raw Milk

Antibiotic residues in milk are a serious health and technological problem in dairy processes. This study aims to verify the absence of administered antimicrobials after therapeutic treatments, taking into consideration the withdrawal period, and to evaluate the reliability of screening tests under field conditions after confirmatory HPLC-HRMS (High Performance Liquid Chromatography-High-Resolution Mass Spectrometry) Orbitrap analysis. Moreover, the presence of expected or non-targeted metabolites was investigated using the new Compound Discoverer approach. The presence of antimicrobial drugs was shown in 29% of the samples, and also sometimes their metabolites (for enrofloxacin and lincomycin), despite the fact that samples were collected at the seventh milking. Moreover, in 9% of the samples, undeclared treatments were revealed due to the presence of both parent drugs and metabolites. Lastly, the putative identification of two new enrofloxacin metabolites, ENRO-N-methylacetamide and ENRO-ornithine, was proposed. In the light of this evidence, it must be borne in mind that metabolites, some of which are pharmacologically active, may also pose a risk to consumers and for the entire processing of milk in the cheese industries.

Determination of residual enrofloxacin in eggs due to long term administration to laying hens. Analysis of the consumer exposure assessment to egg derivatives

The use of the antibiotic enrofloxacin (ENR) in poultry is controversial. A high-performance liquid chromatography coupled to fast-scanning fluorescence detection (HPLC-FSFD) method for the determination of ENR in egg white, egg yolk, and lyophilized samples was developed. In a first analysis, the long-term administration of ENR (100 days) to laying hens was carried out to determine its presence in egg white, yolk, or both. The predominance of ENR was observed in egg white and variations in the weight of egg white and eggshell was evidenced, showing a potential problem in the industry. Eventually, the presence of ENR was confirmed in commercial lyophilized egg white samples in concentration values around 350 µg kg^-1. The consumer exposure assessment was estimated for children, adolescents, and adults. The result displayed that, in an intake of lyophilized egg white with food-producing animals, the %ADI exceeds 100%, showing toxicological levels.