Doxycycline depletion and residues in eggs after oral administration to laying hens

Study on the Metabolic Transformation Rule of Enrofloxacin Combined with Tilmicosin in Laying Hens

There is often abuse of drugs in livestock and poultry production, and the improper use of drugs leads to the existence of a low level of residues in eggs, which is a potential threat to human safety. Enrofloxacin (EF) and tilmicosin (TIM) are regularly combined for the prevention and treatment of poultry diseases. The current studies on EF or TIM mainly focus on a single drug, and the effects of the combined application of these two antibiotics on EF metabolism in laying hens are rarely reported. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine the residual EF and TIM in laying hens and to investigate the effect of TIM on the EF metabolism in laying hens. In this paper, we first establish a method that can detect EF and TIM simultaneously. Secondly, the results showed that the highest concentration of EF in the egg samples was 974.92 ± 441.71 μg/kg on the 5th day of treatment. The highest concentration of EF in the egg samples of the combined administration group was 1256.41 ± 226.10 μg/kg on the 5th day of administration. The results showed that when EF and TIM were used in combination, the residue of EF in the eggs was increased, the elimination rate of EF was decreased, and the half-life of EF was increased. Therefore, the use of EF and TIM in combination should be treated with greater care and supervision should be strengthened to avoid risks to human health.

Withdrawal Interval Estimation of Doxycycline in Yellow Catfish (Pelteobagrus fulvidraco) Using an LC-MS/MS Method Based upon QuEChERS Sampling Preparation

Limited information on residue depletion of doxycycline (DC) is available in yellow catfish (Pelteobagrus fulvidraco) using the determination of LC-MS/MS based upon a rapid and simple method of sample preparation. This study collected plasma and tissue samples of yellow catfish at pre-determined time points following 3-day consecutive oral administration of DC at 20 mg/kg. The samples were prepared using a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) approach. The limit of detection and the limit of quantitation were 2.5 and 5 µg/kg or µg/L, respectively, for DC in plasma and tissues (e.g., muscle + skin, liver, kidney, and gill). The recoveries of DC ranged from 67.2% to 86.2%. The decision limit (CCα) and the detection capability (CCβ) were from 106.2 to 127.8 μg/kg or μg/L. The withdrawal times of DC in muscle + skin were estimated to be 22 d based on the guidelines in China and Europe and 27 d based on Japan's standard. Overall, this study not only provides an efficient method to rapidly determine the DC concentrations in fish-derived tissues but also provides important information on the safety assessment of DC in aquatic animal-derived food products.

The vertical transmission of antibiotic residues from parent hens to broilers

Imprudent and superfluous use of antibiotics contributes to the selection of resistant bacteria, which is a large threat to human health. Therefore analytical procedures have been implemented in the poultry production sector to check if antibiotic treatments are registered, aiming to achieve more prudent use of antibiotics. These methods rely on the analysis of feathers, a matrix in which antibiotic residues persist. However, other routes besides direct administration, through which poultry feathers could contain antibiotic residues, should also be taken into account. In this research the vertical transmission from parent hen to broiler was investigated through a controlled animal study for the antibiotics enrofloxacin, doxycycline and sulfachlorpyridazine. Vertical transmission was observed for all antibiotics to both egg and egg shell. Also it is demonstrated that the transferred antibiotics from parent hen to chick are subsequently excreted via the chick's droppings. Through this route, the broilers' environment is contaminated. If eggs are hatched that were taken during treatment of the parent hen, this indirect route and/or the direct vertical transmission can eventually result in the detection of low concentrations of antibiotic residues in the broilers' feathers at greater age: <50 µg kg^-1 for freely extractable residues and <10 µg kg^-1 for non-freely extractable residues. No antibiotics were detected in the broilers' muscle or kidney from 4 weeks of age. This research provides relevant information regarding the possible amount of residues originating from vertical transmission when monitoring matrices such as feathers and broiler droppings in order to stimulate correct use and registration of antibiotics in the poultry sector.

Contamination of hen manure with nine antibiotics in poultry farms in Ukraine

The problem of processing, use and utilization of poultry manure contaminated with antibiotics remains unsolved not only Ukraine but around the world, and theatment and prevention of highly contagious infectious diseases among birds requires antibacterial medication use. By liquid chromatography, 293 hen manure samples of 12 Ukrainian industrial flocks of poultry farms were studied. The residual content of 9 antibiotics in the hen manure was found, including 38.2% of tetracycline preparations (doxycycline, oxytetracycline, tetracycline and chlortetracycline), fluoroquinolone (enrofloxacin and norfloxacin) including combinations of incompatible tetracyclines and fluoroquinolones, broad-spectrum penicillins (amoxicillin), fenicols (florfenicol), macrolides (tylosin) and one sulfanilamide preparation (sulfametazine). The most common antibiotics in hen manure of Ukrainian industrial flocks of poultry farms are the antibiotics of the tetracycline group, the main one being doxycycline. A high correlation was determined between the release of doxycycline with eggs and hen manure after the preparation was used perorally in preventive and therapeutic doses. Time of complete excretion of doxycycline from the hen body at the preventive dose (50 mg/L of water for 7 days) was 14 days for manure, 8 days for eggs, following its withdrawal, and at the therapeutic dose (100 mg/L of water for 7 days ) – 20 days for manure, and 9 days for eggs, following its withdrawal. The perspective of using the obtained data about the duration of excretion of doxycycline with hen manure consists in confirmation of the time of the antibiotic’s excretion with manure following its use for preventive or therapeutic purpose, which will help in controlling it as a source of environmental pollution. The time of doxycycline excretion from the body of hens with eggs and manure may be used practically by professionals in veterinary medicine in the case of prescribing or replacing antibiotics for treatment of infectious diseases of poultry to prevent the combination of incompatible preparations in the body and manure. The obtained experimental data may form the basis for the development of national regulations on the processing, usage and utilization of manure of hens under treatment with antibiotics.

Evaluation of Tilmicosin Contamination in Eggs Following Its Administration to Laying Hens and Subsequent Assessment of Dietary Risks to Chinese Consumers

In the present study, we analyzed the tilmicosin residues in eggs as well as the dietary risks posed by the residual drug to Chinese consumers. Tilmicosin was administrated to laying hens via drinking water in doses of 100 mg/L and 300 mg/L (dose 1 and dose 2) for 5 days. Its residues distribution within egg matrices were detected using a QuEChERS method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results indicated that the tilmicosin residue was the highest in the whole eggs and yolks on day 2 after medication and in the whites on day 5 of drug administration for dose 1 and dose 2 with the residues (µg/kg) being the following: 73.4 and 444.3 in the whole eggs; 152.0 and 1141.1 in the yolks; and 48.8 and 277.6 in the whites, respectively. During withdrawal phase, the tilmicosin levels declined to less than the limit of detection (LOD) after 29 days and 49 days for the whole eggs, after 24 days and 44 days for the yolks, and after 19 days and 49 days for the whites for doses 1 and 2, respectively. An assessment of the dietary risk for Chinese consumers revealed that the hazard quotients (HQ) values for tilmicosin consumption were less than 1 for dose 1 and greater than 1 for dose 2, with children (2 to 7 years) and adult males (over 65 years) being the high-risk groups. These results suggest that the possible risk associated with tilmicosin contamination in eggs should not be ignored since the accidental or occasional misuse of tilmicosin in the case of egg-laying hens may occur from time to time, particularly on small farms. PRACTICAL APPLICATION: The modified QuEChERS method was used to analyze the tilmicosin residues in egg matrices and a subsequent dietary exposure assessment for Chinese consumers was performed, which can serve as a reference for the food safety risk posed by antibiotic misuse in egg layers.

Tissue residue depletion kinetics and withdrawal time estimation of doxycycline in grass carp, Ctenopharyngodon idella, following multiple oral administrations

This study aimed to determine the plasma and tissue residue depletion kinetics of doxycycline (DC) in grass carp (Ctenopharyngodon idella) after daily oral administrations at 20 mg/kg for 3 days, and to calculate the corresponding withdrawal times. Following drug administrations, samples of plasma, liver, kidney, gill and muscle + skin were collected at predetermined time points (0.25, 0.5, 1, 3, 5, 7, 14, 21, 28, 35, 42, 49 and 56 days) and analyzed for concentrations of DC using a LC-MS/MS method. The results showed that liver had the highest concentrations and the slowest depletion compared to other tissues, with detectable DC up to 49 days (58.9 ± 12.8 μg/kg). The WT 1.4 software and "reschem" package were used to calculate withdrawal times, and the results were similar. The results suggest a withdrawal time of 41 days for Europe and China and 50 days for Japan is needed for DC in grass carp after 3 daily oral administrations at 20 mg/kg. Overall, this study improves our understanding of the tissue residue depletion kinetics of DC in fish, and the results may help regulatory agencies to determine proper withdrawal periods based on different regulatory standards in different countries to ensure safety of aquatic food products.

Tetracycline antibiotics transfer from contaminated milk to dairy products and the effect of the skimming step and pasteurisation process on residue concentrations

The presence of antibiotics in raw milk and milk derivatives poses a threat to human health and can negatively affect the dairy industry. Therefore, the main object of this study was to investigate the transfer of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC) and doxycycline (DC) from raw, experimental milk contaminated with tetracyclines (TCs) to different dairy products: cream, butter, buttermilk, sour milk, whey, curd and cheese. Additionally the effect of the skimming process on TCs concentrations was tested, as well as the influence of low-temperature long-time pasteurisation. The analyses of TCs in milk and dairy products were performed by an LC-MS/MS method. In order to determine TCs residues in dairy products, an analytical method was developed with the same extraction step for all matrices. TCs molecules were inhomogenously distributed between the milk derivative fractions. The highest concentrations were determined in curd and cheese in the ranges 320-482 µg/kg and 280-561 µg/kg, respectively. Low levels of TCs in butter and whey were observed (11.8-41.2 µg/kg). TCs were found in sour milk (66.0-111 µg/kg), cream (85.0-115 µg/kg) and buttermilk (196-221 µg/kg) at much higher levels than in butter and whey, but lower than in curd and cheese. During the skimming process, the highest yield of cream was obtained after the raw milk was held at 2-8°C for 24 h. The differences in concentrations of TCs between whole milk and skimmed milk, expressed as percentages of recovery, were below 19% (recoveries in excess of 81%). The highest content was observed in milk and cream skimmed at 2-8°C. The degradation percentages for TCs during the pasteurisation process (63°C for 30 min) were below 19%.

Validation of an UHPLC-MS/MS Method for Screening of Antimicrobial Residues in Eggs and Their Application to Analyses of Eggs from Laying Hens Subjected to Pharmacological Treatment

A multiresidue method by UHPLC/MS-MS was optimized and validated for the screening and semiquantitative detection of antimicrobials residues from tetracyclines, aminoglycosides, quinolones, lincosamides, β-lactams, sulfonamides, and macrolides families in eggs. A qualitative approach was used to ensure adequate sensitivity to detect residues at the level of interest, defined as maximum residue limit (MRL), or less. The applicability of the methods was assessed by analyzing egg samples from hens that had been subjected to pharmacological treatment with neomycin, enrofloxacin, lincomycin, oxytetracycline, and doxycycline during five days and after discontinuation of medication (10 days). The method was adequate for screening all studied analytes in eggs, since the performance parameters ensured a false-compliant rate below or equal to 5%, except for flumequine. In the analyses of eggs from laying hens subjected to pharmacological treatment, all antimicrobial residues were detected throughout the experimental period, even after discontinuation of medication, except for neomycin, demonstrating the applicability of the method for analyses of antimicrobial residues in eggs.

The influence of cooking procedures on doxycycline concentration in contaminated eggs

Doxycycline (DC) is forbidden compound in laying hens. Most information about drug residues in eggs concern their concentrations in raw matrix and the data about the influence of cooking on antibiotics residues in eggs are limited. Thus, the residues concentration of DC in eggs after different cooking methods was investigated. Analyses of DC were assayed by liquid chromatography - tandem mass spectrometry method. The stability of DC in eggs were depended upon the type and time of cooking procedure. By microwaving DC was reduced most effective with concentrations decreased by 53% and 50.3% after 4min of microwaving without cover and microwaving with cover, respectively. In fried eggs, DC was reduced by 39.8% in 6min. By the boiling cooking, the smallest reduction was observed with the concentration decreased by 29.8% after 8min. The obtained results show that ordinary cooking does not eliminate the all DC residues present in eggs.

Effect of doxycycline concentrations in chicken tissues as a consequence of permanent exposure to enrofloxacin traces in drinking water

Introduction: The main problem in poultry farming is the difficulty in producing food of animal origin without using antibacterial agents. Because most antibacterial compounds are dispensed in water, some water supply systems can be contaminated by antibiotics which are then administered to the animals unintentionally. This can lead to unexpected increases in antibiotic residues in food of animal origin. The aim of the present study was to determine whether the constant exposure of chicken broilers to enrofloxacin affects the withdrawal time of a therapeutic doxycycline that is intentionally administered to the chickens.

Material and Methods: The concentrations of doxycycline, enrofloxacin, and ciprofloxacin were determined by LC-MS/MS in muscles and liver of the chickens.

Results: Doxycycline residue concentrations in the chicken tissues from the group that received trace amounts of enrofloxacin were nearly 50% greater than those of the group that received only doxycycline.

Conclusion: These results indicated that constant exposure to enrofloxacin in trace amounts significantly influences the residual doxycycline concentration in chicken tissues.