Detection and determination of stability of the antibiotic residues in cow's milk

Responses of intestinal morphology, immunity, antioxidant status and cecal microbiota to the mixture of glycerol monolaurate and cinnamaldehyde in laying hens

This study was to determine the effects of the mixture of glycerol monolaurate and cinnamaldehyde (GCM) supplementation on the intestinal morphology, immunity, antioxidant status and cecal microbiota of laying hens. A total of 1,120 healthy laying hens (Jingfen-1 strain) at the age of 14 wk were randomly divided into 4 groups with 10 replicates of 28 layers in each and layers were fed diets containing 0 (control group), or 250, 500, and 1,000 mg/kg GCM for 12 wk. The results showed that dietary supplementation with GCM significantly increased intestinal villus height and villus height/crypt depth, duodenal villus area, total superoxide disumutase activities in the liver and jejunum, jejunal glutathione peroxidase activities while decreased duodenal and jejunal crypt depth, hydrogen peroxide content in the liver and jejunal malondialdehyde content of laying hens aging 28 wk (P < 0.05). Meanwhile, GCM addition significantly increased serum immunoglobulin A and immunoglobulin M concentration of layers at the age of 20, 24, and 28 wk (P < 0.05). Moreover, it was observed in the 16S rRNA sequencing that the addition of GCM elevated the abundance and diversity of gut microbiota in laying hens. The predominant bacteria from each group were Bacteroidota and Firmicutes at the phylum level and Bacteroides and Lactobacillus were the dominant genera. The composition and structure of cecal microflora were changed by the addition of GCM to the diet of laying hens. In conclusion, the addition of GCM (500-1,000 mg/kg diet) can improve intestinal morphology, immune function, intestinal and liver antioxidant status and intestinal flora of laying hens, thereby improving intestinal digestion and absorption capacity. These findings provide a new way to further explore the mechanism of GCM improving intestinal health.

Understanding Knowledge and Attitude of Farmers towards Antibiotic Use and Antimicrobial Resistance in Jhunjhunu District, Rajasthan India

The misuse of antibiotics in veterinary practices by farmers is harming livestock production and food safety and leading to the rise of antibiotic resistance (AMR). This can also transfer resistant bacteria from animals to humans, posing a serious public health threat. However, we have not paid enough attention to understanding how farmers behave in this regard. Our study aims to explore farmers' behaviors and identify the factors that influence their choices. To conduct this study, we used a questionnaire with 40 questions and surveyed 208 farmers in Jhunjhunu district, Rajasthan. We analyzed the data using SPSS. Here are the key findings: About 58.3% of the farmers have some awareness of antibiotics, and 49.5% are aware of antimicrobial resistance (AMR). Notably, as the level of education increases, so does awareness of antibiotics. Unfortunately, 63.9% of the farmers are not aware of the withdrawal time, and 64% have no idea about the presence of antibiotic residues during this period. Around 75% of farmers vaccinate their animals, but approximately 56.9% of individuals have never undergone an antibiotic sensitivity test (ABST) for milk. Around 48.6% of farmers are unaware of government testing centers. Several factors hinder farmers from implementing proper animal management practices, such as the high fees of veterinarians. When their animals become sick, their first choice is home remedies, followed by using old prescriptions. Additionally, 63.9% stop treatment once the animal looks better. A significant portion (83.8%) of farmers rely on local pharmacists for medicine. It has been determined that there is no significant correlation between education, experience, age, and the level of awareness concerning withdrawal periods, the existence of government antibiotic sensitivity test (ABST) centers, and entities responsible for sending samples for ABST. In our qualitative analysis, focus groups identified significant barriers to following best farm practices and spreading awareness about AMR. These findings suggest that addressing AMR in livestock requires a comprehensive approach. This should include targeted education and awareness programs for farmers, as well as improved access to veterinary services.

Antibiotic residues in milk and dairy products in China: occurrence and human health concerns

Although veterinary antibiotics are essential in preventing and treating clinical diseases in cattle, the frequent use of antibiotics leads to antibiotic residues in milk and dairy products, consequently threatening human health. The massive milk consumption makes it necessary to assess antibiotic pollution and health impact comprehensively. Hence, we conducted a systematic review to evaluate antibiotics in milk and dairy products and their potential health risk. We searched four databases using multiple keyword combinations to retrieve 1582 pieces of literature and finally included eighteen articles to analyze antibiotic residues in milk and dairy products. These studies detected seven antibiotics in different regions of China. Quinolones and β-lactam antibiotics exceeded the MRL for raw and commercial milk. The maximum levels of sulfonamides and tetracyclines were detected in the same raw milk sample, exceeding the MRL. The estimated THQ and HI values in milk and dairy products are less than 1 for adults, indicating negligible noncarcinogenic health risk of antibiotics through consuming milk and dairy products. Children face higher health risks than adults, with the HI and THQ of quinolones exceeding 1. It is worth noting that quinolones accounted for nearly 89% of health risks associated with all antibiotics. Finally, we put forward possible research directions in the future, such as specific health effects of total dietary exposure to low levels of antibiotics. In addition, policymakers should effectively improve this problem from the perspectives of antibiotic use supervision, antibiotic residue analysis in food, and continuous environmental monitoring and control.

Tetracycline residues in fresh dairy milk from three districts in Indonesia: Occurrence and dietary exposure assessment

Background and Aim

Milk can introduce antibiotics into the human diet which poses a public health risk. Therefore, a study to determine the tetracycline residue in dairy milk and its health risk assessment is needed. A cross-sectional study was performed to detect tetracycline residues in fresh dairy milk samples collected from the districts of Malang, Boyolali, and Padang Panjang, Indonesia, and to evaluate dietary exposure to tetracycline residues through milk consumption in 10-12-year-old children and adults.

Materials and Methods

A total of 203 fresh dairy milk samples were collected from local and smallholder dairy cows in Malang, Boyolali, and Padang Panjang in April and August 2018. High-performance liquid chromatography equipped with a photodiode array at 355 and 368 nm was used to detect tetracycline residues. Data were evaluated for dietary exposure assessment.

Results

The results showed that the most common residue found was chlortetracycline (8.37%), followed by tetracycline (7.88%) and oxytetracycline (5.91%) in the concentration range of 14.8-498.4, 11.7-49.4, and 11.6-85.6 ng/g, respectively. Seven (3.45%) samples exceeded the maximum residue limit (MRL) for chlortetracycline. However, neither oxytetracycline nor tetracycline residues exceeded the MRL. The mean concentration of the tetracycline residues was 21.76-137.05 ng/g, resulting in an estimated daily intake of 16.46-172.83 ng/kg body weight/day.

Conclusion

Tetracycline residues were found in almost all milk sampling locations. The highest prevalence and residue concentration were obtained from chlortetracycline. Estimated daily intake of tetracycline through milk by 10-12-year-old children and adult consumers was low and the risk to consumers was negligible.

Microbiota and Resistome Analysis of Colostrum and Milk from Dairy Cows Treated with and without Dry Cow Therapies

This study investigated the longitudinal impact of methods for the drying off of cows with and without dry cow therapy (DCT) on the microbiota and resistome profile in colostrum and milk samples from cows. Three groups of healthy dairy cows (n = 24) with different antibiotic treatments during DCT were studied. Colostrum and milk samples from Month 0 (M0), 2 (M2), 4 (M4) and 6 (M6) were analysed using whole-genome shotgun-sequencing. The microbial diversity from antibiotic-treated groups was different and higher than that of the non-antibiotic group. This difference was more evident in milk compared to colostrum, with increasing diversity seen only in antibiotic-treated groups. The microbiome of antibiotic-treated groups clustered separately from the non-antibiotic group at M2-, M4- and M6 milk samples, showing the effect of antibiotic treatment on between-group (beta) diversity. The non-antibiotic group did not show a high relative abundance of mastitis-causing pathogens during early lactation and was more associated with genera such as Psychrobacter, Serratia, Gordonibacter and Brevibacterium. A high relative abundance of antibiotic resistance genes (ARGs) was observed in the milk of antibiotic-treated groups with the Cephaguard group showing a significantly high abundance of genes conferring resistance to cephalosporin, aminoglycoside and penam classes. The data support the use of non-antibiotic alternatives for drying off in cows.

Microbiological safety and quality survey of some dairy confectioneries with cream filling and topping

Background

Dairy confectionaries are recently categorized as an important part of different consumers' diets with increasing demand for cream-based cakes "Tourta" and gateau which are used as celebrating food for almost all occasions and celebrations.

Aim

The study was designed for evaluating general quality and safety of such products.

Methods

100 cream-based (for topping and filing) samples; 50 cakes "Tourta" and 50 gateau, were purchased separately from several pastry shops covering international, national, and local brands in Great Cairo, Egypt, and subjected to microbiological analysis.

Results

Results showed that international brands were the best for gateau samples while national brands were the best quality for cake samples. Regardless of the brand, the general hygienic quality of the cake product "Tourta" was lower on an average total colony, coliforms, yeast, and mold counts as compared with the gateau product. Although coliforms were found in 100% of the examined samples with the highest mean value of 33 × 102 ± 7.0 × 102 CFU/g in local gateau samples, Escherichia coli and Salmonella spp. could not be detected in these samples. Staphylococcus aureus was isolated from 8% of the total examined samples with the highest incidence of (22.2%) and a mean count of 38 × 10 ± 6.0 × 10 CFU/g in local brand gateau samples. Bacillus cereus was extensively isolated with the highest incidence in cake samples (32%) and mean counts higher than 103 in all of the examined samples. Bacillus cereus strains have harbored more than one toxigenic gene. In this aspect, nhe gene was the most predominant one as it was detected in 100% of the examined isolates, followed by cytK gene in 80%, whilehbl and ces genes could not be found. According to the Egyptian Standard specifications for cake (ES: 4037/2020), a higher acceptability degree was reported for the international brand gateau and cake "Tourta" samples. The incidence of using any preservative as an inhibitory substance was also analyzed generally using the Bacillus subtilis disk assay technique, but all samples were negative using this technique indicating the need for a more advanced technique for its detection such as using high-performance liquid chromatography.

Conclusion

Finally, it was concluded that; more attention is needed to cream-based cakes' quality and safety, with essential modification required in the standards of cakes in Egypt.

Analysis, Occurrence and Exposure Evaluation of Antibiotic and Anthelmintic Residues in Whole Cow Milk from China

An optimized QuEChERS method for the simultaneous extraction of 26 antibiotics and 19 anthelmintics in whole cow milk was established, followed by UHPLC-MS/MS analysis. Briefly, 20 mL acetonitrile with 1 g disodium hydrogen citrate, 2 g sodium citrate, 4 g anhydrous MgSO₄, and 1 g sodium chloride were added to 10 g milk for target chemical extraction, followed by 50 mg anhydrous MgSO₄ for purification. Satisfactory recoveries were obtained using the modified QuEChERS method, with recoveries of the antibiotics ranging from 79.7 to 117.2%, with the exception of norfloxacin, which was at 53.4%, while those for anthelmintics were in the range of 73.1-105.1%. The optimized QuEChERS method presented good precision, with relative standard deviations ranging from 7.2 to 18.6% for both antibiotics and anthelmintics. The method was successfully applied to analyze the antibiotics and anthelmintics in 56 whole cow milk samples from China. Briefly, the detection frequencies and concentrations of most of the antibiotics and anthelmintics were low in the whole cow milk samples, with concentrations ranging from below LOD to 4296.8 ng/kg. Fenbendazole, febantel, enrofloxacin, levofloxacin, sulfadiazine, and sulfamethoxazole were the predominant drug residues in the whole cow milk samples. Spatial distribution was found for those antibiotics and anthelmintics with detection frequency higher than 50%, especially for the antibiotics, indicating regional differences in drug application. Based on the current study, exposure to antibiotics and anthelmintics through whole cow milk consumption are lower than the acceptable daily intake values suggested by the China Institute of Veterinary Drug Control. However, long-term exposure to low doses of antibiotics and anthelmintics still needs attention and merits further study.

Efficiency of probiotic culture consortium application for disinfection of dairy farm premises and prevention of mastitis in cows

Objective

In this work, the effect of probiotics on the state of the microbial background of the livestock building, on the state of udder teats, and on the prevalence of latent mastitis was investigated. Long-term use of the consortium has bactericidal activity against all cultures studied, especially the causative agent of mastitis, Staphylococcus aureus, except Proteus mirabilis, Proteus vulgaris, and Escherichia coli.

Materials and Methods

The washes from animal housings and milk samples were collected from the dairy farms "Astana-Onim" Joint Stock Company and "Rodina" Limited Liability Partnership (Kazakhstan). The cleaning solutions and probiotic agents were applied directly to the udder teats of cows before and after milking. Diagnosis of subclinical mastitis was performed using the Kenotest rapid mastitis test. Directly counting the number of somatic cells in the collected milk samples from each cow was performed on a somatic cell counter.

Results

Pathogenic microorganisms, including S. aureus bacteria (50% of samples) and bacteria of the E. coli group, Enterobacter aerogenes, and P. mirabilis (36% of samples), were detected on the udder skin and milk wipes. Using a consortium of probiotic microorganisms positively affects the mammary gland more quickly than using mastitis prevention agents alone. Probiotic use for a month resulted in a significant improvement in udder teat condition, with 60.7% of teats showing normal physiological reaction to milking, a decrease in complicated hyperkeratosis, and an increase in uncomplicated mastitis. The studies showed that in the experimental group, there was a 1.5-fold reduction in the number of cows with clinically pronounced mastitis. The experimental group showed no significant changes in the number of animals with high somatic cell levels before and after the study, while the control group without probiotics had a significant increase in diseased animals after 1 month.

Conclusion

The use of a probiotic consortium has shown promising results in reducing the incidence of mastitis and improving milk quality in cows.

Antibiotic-resistant bacteria in bovine milk in India

Antibiotic resistance (ABR) is a global issue that draws the attention of all healthcare experts in the veterinary and medical fields. Of various factors, indiscriminate and unregulated antibiotic usage in the animals reared for food production, especially in cows and buffaloes suffering from mastitis, contribute significantly to the rising incidence of resistant bacteria. A literature survey reveals the spread of resistant strains of mastitis-causing bacteria, like Staphylococcus aureus and Escherichia coli, to humans. In addition, antibiotic residues detected in milk samples against all major groups of antibiotics are likely to enter the human body through the food chain and aggravate the condition. The cumulative effects of ABR have emerged as a silent killer. The benefits of systematic surveillance on ABR in India are yet to be available. Here is an attempt to understand the ABR burden in India associated with bovine milk and its mitigation strategies.

Multifunctional fluorescent Eu-MOF probe for tetracycline antibiotics and dihydrogen phosphate sensing and visualizing latent fingerprints†‡

The contamination of tetracycline antibiotics and dihydrogen phosphate (H₂PO₄⁻) in food and the environment is one of the major concerns for human health. Herein, a water-stable carboxyl-functionalized europium metal–organic framework (Eu-MOF) was prepared and demonstrated, for the first time, as a dual-responsive fluorescent sensor of tetracycline antibiotics (oxytetracycline (OTC), tetracycline (TC), and doxycycline (DOX)) and H₂PO₄⁻via fluorescent turn-on and turn-off, respectively. Eu-MOF presents a sensitive and selective detection of OTC with a rapid response time (1 min) and good anti-interference ability. The limits of detection (LODs) of 78 nm, 225 nm, and 201 nM were achieved for OTC, TC, and DOX, respectively. Coordination and hydrogen bonding led to energy and electron transfer from the TC to the MOF, contributing to the fluorescent enhancement mechanism. Moreover, Eu-MOF can effectively detect H₂PO₄⁻via fluorescence turn-off with a LOD of 0.70 μM. The interactions between H₂PO₄⁻ and MOF interrupt the energy transfer from ligand to MOF, leading to fluorescence quenching. In addition, Eu-MOF was successfully applied to determine OTC and H₂PO₄⁻ in real samples, obtaining satisfactory recoveries and RSDs. More fascinating, Eu-MOF could be utilized to develop latent fingerprints on various surfaces, providing well-defined fluorescent fingerprint details in which the sweat pores can be seen with the naked eye.

Water-stable Eu-MOF as a fluorescent probe for detecting tetracycline antibiotics and dihydrogen phosphate in real samples and visualization of latent fingerprints.

Simultaneous Screening of Six Families of Antibiotic Residues in Milk Samples by Biochip Multi-array Technology

Background

Antimicrobial compounds are used in animal husbandry to prevent and treat bacterial diseases and as illegal growth-promoting agents. Due to the excessive and inappropriate use of antibiotics, the antibiotic residues in milk can cause allergic reactions and antibiotic resistance. A rapid biochip-based method for the multi-analyte screening of 6 families of antibiotic residues (quinolones, ceftiofur, florfenicol, streptomycin, tylosin, and tetracyclines) in milk was validated based on Commission Decision 2002/657 and the European guidance for screening methods for veterinary medicinal products.

Methods

This methodology allows the 6 antibiotic families to be detected simultaneously, increasing the screening capacity and reducing costs in test settings. The method's applicability was shown by screening 38 UHT cow milk samples taken from Tehran province, IR Iran.

Results

The results showed that the positive threshold T was above Fm, and the CCβ was below the European Commission's Maximum Residue Limit (MRL) (100 ppb for ceftiofur and tetracycline and 50 ppb for tylosin in milk). Norfloxacin was detected in about 8% of the samples and tylosin in 2.63%. The total antibiotic concentration in UHT cow milk samples was lower than the European Commission's MRL.

Conclusions

This study showed that the biochip technique is valid for screening tylosin, ceftiofur, streptomycin, tetracycline, norfloxacin, and florfenicol in milk. It was found that the method was easy, quick, and capable of detecting 6 families of antibiotic residues simultaneously from a single milk sample without sample preparation.

Antibiotic residues in milk and milk products: A momentous challenge for the pharmaceutical industry and medicine

Dairy products are nutritious food items that contain various essential nutrients, however, it has been proven that residual antibiotics have contaminated such products. These residues can cause several side effects on human health. They increase antimicrobial resistance against several threatening microorganisms, as well as significant growth in allergenic reactions. Various methods, including heat treatments, have been applied to alleviate and reduce the effect of antibiotic residue level in milk and milk products. Changes in drug levels were not significantly remarkable, obliging researchers to find new approaches to prevent or reduce their risk and limit their complications on human health.

Challenges and a potential solution to perform drug susceptibility testing of omadacycline against nontuberculous mycobacteria

BACKGROUND

Minimum inhibitory concentration (MIC) of slow growing mycobacteria (SGM) often do not correlate with the treatment response. Among the challenges is the identification of MIC of drugs that degrade in solution faster than the doubling time of the SGM.

METHODS

First, we identified the rate of omadacycline degradation in solution, and its effect on the rapidly growing methicillin resistant Staphylococcus aureus (MRSA). We then identified doubling times versus MICs for Mycobacterium abscessus, M. avium, and M. kansasii, with and without supplementation for degraded drug.

RESULTS

Omadacycline concentration in solution declined ∼50% over 24hr. In the MRSA experiments, omadacycline demonstrated 66.48 ± 19.38% loss in potency over 24hr, confirming the degradation rate in solution. M. abscessus had a doubling time of 8.75 ± 1.23hr and the omadacycline MIC after 24hr of incubation was 2mg/L with and without 50% daily drug supplementation, indicating that drug degradation had no effect on this rapid grower. The doubling time for M. avium was 29.52hr (95% confidence interval (CI): 23.18-33.89hr) and 31.15hr (95%CI: 19.45-38.49 hr) for M. kansasii. The M. avium MICs ±50% daily omadacycline supplementation were 1mg/L and 0.5mg/L on day 7, whereas the M. kansasii MICs ±50% daily supplementation were >128mg/L and 32mg/L on day 7.

CONCLUSION

Omadacycline degradation in solution leads to falsely high MICs when SGM doubling time exceed the drug degradation rates in solution. The challenge could be overcome by daily drug supplementation to account for the loss of potency, which is laborious, or perhaps stabilizing the drug from degradation.

Effects of Plant-Derived Glycerol Monolaurate (GML) Additive on the Antioxidant Capacity, Anti-Inflammatory Ability, Muscle Nutritional Value, and Intestinal Flora of Hybrid Grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂)

In a context where the search for plant-derived additives is a hot topic, glycerol monolaurate (GML) was chosen as our subject to study its effect on grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). Seven gradient levels of GML (0, 600, 1200, 1800, 2400, 3000, and 3600 mg/kg) were used for the experiment. Based on our experiments, 1800 mg/kg GML significantly increased the final body weight (FBW) and weight gain rate (WGR). GML increased the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreased malondialdehyde (MDA). Adding 1800 mg/kg GML also significantly increased the levels of lauric acid (C12:0) (LA), n-3 polyunsaturated fatty acids (PFA), and the n-6 PFA-to-n-3/n-6 ratio, while significantly decreasing the levels of saturated fatty acids (SFA). Dietary supplementation with GML significantly inhibited the expression of pro-inflammatory factors and reduced the occurrence of inflammation. GML improved intestinal flora and the abundance of beneficial bacteria (Bacillus, Psychrobacter, Acinetobacter, Acinetobacter, Stenotrophomonas, and Glutamicibacter). It provides a theoretical basis for the application of GML in aquafeed and greatly enhances the possibility of using GML in aquafeed. Based on the above experimental results, the optimum level of GML in grouper feed is 1800 mg/kg.

Depletion of Amoxicillin Residue in Edible Tissue of Broiler Chicken by Different Cooking Methods

A new simple isocratic, RP-HPLC method, was developed and validated to estimate amoxicillin (Amox) residue depletion caused by different cooking methods in broiler chicken tissue. The limit of detection (LOD) and the limit of quantitation (LOQ) were 1.32 and 4.00 µg mL⁻¹, respectively. The calibration plot was linear over the concentration range of 0.05–250 µg mL⁻¹, and the relative standard deviation (RSD) values were less than 8%. The effects of various cooking methods (boiling, pan-frying, and microwaving) on residues of Amox were conducted under different combinations of temperature and time. Moreover, the heat stability of Amox standard solutions under boiling water and cooking oil at 100°C was investigated. Amox remained stable for 5–15 min in boiling water, the concentration was significantly reduced in the range of 70–87%, and additional new peaks of the degraded compounds appeared at 30–45 min. In pan-frying, the residue remained stable for 15 min at 100°C and then depleted to 81–92% after 30–45 min. Due to dehydration, the residue concentration showed an increment from 101 to 112% at 150°C. The total decomposition of Amox was observed at 200°C, 30–45 min due to high temperature and long-time effects. In microwave cooking using 500 W, 0.5–2 min, the depletion was insignificant. This study shows that sufficient cooking temperature and time can have a significant effect on the depletion of Amox residues.

Safety Issues Regarding the Detection of Antibiotics Residues, Microbial Indicators and Somatic Cell Counts in Ewes’ and Goats’ Milk Reared in Two Different Farming Systems

Milk samples of ewes’ and goats’ unprocessed milk were collected from milk tanks from various farms in Epirus, Greece and classified in two groups according to the type of farming. Analyses of the samples included microbial inhibition assays to detect the presence of antibiotic residues, isolation of Staphylococcus aureus and Escherichia coli strains as microbiological indicators for susceptibility to antimicrobial medicines, Somatic Cells and Coagulase Negative Staphylococci (CNS) counts. These findings were correlated with each other as well as to the stage of the lactation period and to the type of the farming practices. Monitoring of bulk tank milk for residues of antibiotics should be performed after heating of the milk, on a regular basis, and should include at least two different tests. The results point out that the type of farming affects the CNS counts as well as the prevalence of residues in the milk. Furthermore, the inverse correlation between CNS counts and prevalence of residues of antibiotics suggests a possible protective role of CNS. Resistance of the bacterial indicators to antibiotics was random and relatively rare, perhaps acquired in past due to misuse of antibiotics, turning the indicator microorganisms to reservoir of resistance.

Transfer of certain beta-lactam antibiotics from cow's milk to fresh cheese and whey

The aim of this study was to investigate the transfer of cephalexin, penicillin-G, and ampicillin & cloxacillin from cow's milk to cheese and whey. For this purpose, raw milk was artificially contaminated to different antibiotic levels and then heat-treated to prepare fresh cheese from it. Antibiotic levels of the milk, whey and cheese were measured with LC-MS/MS. The extent of heat degradation was not sufficient to remove the antibiotic residues from milk. Antibiotic concentrations in whey and fresh cheese were in good accordance with the concentration of the same compound in milk suggesting that contamination of the milk will result in contamination of the product. The investigated antibiotics were transferred less into the cheese curd (1.6-12.5% of the original amount), than into the whey (33.2-74.1%). For penicillin-G even 100% (complete removal) was experienced.

Emerging Electrochemical Sensors for Real-Time Detection of Tetracyclines in Milk

Antimicrobial drug residues in food are strictly controlled and monitored by national laws in most territories. Tetracyclines are a major broad-spectrum antibiotic class, active against a wide range of Gram-positive and Gram-negative bacteria, and they are the leading choice for the treatment of many conditions in veterinary medicine in recent years. In dairy farms, milk from cows being treated with antibiotic drugs, such as tetracyclines, is considered unfit for human consumption. Contamination of the farm bulk tank with milk containing these residues presents a threat to confidence of supply and results in financial losses to farmers and dairy. Real-time monitoring of milk production for antimicrobial residues could reduce this risk and help to minimise the release of residues into the environment where they can cause reservoirs of antimicrobial resistance. In this article, we review the existing literature for the detection of tetracyclines in cow's milk. Firstly, the complex nature of the milk matrix is described, and the test strategies in commercial use are outlined. Following this, emerging biosensors in the low-cost biosensors field are contrasted against each other, focusing upon electrochemical biosensors. Existing commercial tests that identify antimicrobial residues within milk are largely limited to beta-lactam detection, or non-specific detection of microbial inhibition, with tests specific to tetracycline residues less prevalent. Herein, we review a number of emerging electrochemical biosensor detection strategies for tetracyclines, which have the potential to close this gap and address the industry challenges associated with existing tests.

Assessment of various veterinary drug residues in animal originated food products

The veterinary drugs are broad-spectrum antibacterial antibiotics; it uses to cure the animal disease. Many countries have banned veterinary drug residues like nitrofurans metabolites, chloramphenicol. However, the people were administrated veterinary drugs to animals as illegal to increase the milk production in animals for economic benefit. The results of illegally use of veterinary drugs remain as a residue in animal product like milk and it is very harmful to whom consume it cause cancer and allergic for human being which has entered the concern among milk consumers. To control illegal use of veterinary drugs, the government of India has restricted its use in animals. For the identification and confirmation of veterinary drug residues in animal products, analytical techniques such as liquid chromatography and mass spectrometry are available. These are very sophisticated equipments which are available nowadays and their methodologies for the analytical method validation are described by European commission 2002/657/EC. The use of veterinary drugs is a big challenge to effectively identify and authorization of their use. There are so many analytical techniques are using very effectively and taking very less time to protect the consumers from their adverse effects. These techniques take very less time to identify more groups of compounds such as tetracycline, sulfonamides, anthelmintic, and macrolides in single multi-residue method. These methods having validation parameters include system precision, calibration curve, accuracy, limit of detection, and quantification. Therefore, improvement in the existing technologies and accessibility of new screening methodologies will give opportunities for automation that helps in obtaining the results in very less time and improved sensitivity and specificity which contribute to better safety assurance, standard, and quality of various food products of animal origin.

Current Strategies for Studying the Natural and Synthetic Bioactive Compounds in Food by Chromatographic Separation Techniques

The present study summarizes the new strategies including advanced equipment and validation parameters of liquid and gas chromatography methods i.e., thin-layer chromatography (TLC), column liquid chromatography (CLC), and gas chromatography (GC) suitable for the identification and quantitative determination of different natural and synthetic bioactive compounds present in food and food products, which play an important role in human health, within the period of 2019–2021 (January). Full characteristic of some of these procedures with their validation parameters is discussed in this work. The present review confirms the vital role of HPLC methodology in combination with different detection modes i.e., HPLC-UV, HPLC-DAD, HPLC-MS, and HPLC-MS/MS for the determination of natural and synthetic bioactive molecules for different purposes i.e., to characterize the chemical composition of food as well as in the multi-residue analysis of pesticides, NSAIDs, antibiotics, steroids, and others in food and food products.

Advances in therapeutic and managemental approaches of bovine mastitis: a comprehensive review

Mastitis (intramammary inflammation) caused by infectious pathogens is still considered a devastating condition of dairy animals affecting animal welfare as well as economically incurring huge losses to the dairy industry by means of decreased production performance and increased culling rates. Bovine mastitis is the inflammation of the mammary glands/udder of bovines, caused by bacterial pathogens, in most cases. Routine diagnosis is based on clinical and subclinical forms of the disease. This underlines the significance of early and rapid identification/detection of etiological agents at the farm level, for which several diagnostic techniques have been developed. Therapeutic regimens such as antibiotics, immunotherapy, bacteriocins, bacteriophages, antimicrobial peptides, probiotics, stem cell therapy, native secretory factors, nutritional, dry cow and lactation therapy, genetic selection, herbs, and nanoparticle technology-based therapy have been evaluated for their efficacy in the treatment of mastitis. Even though several strategies have been developed over the years for the purpose of managing both clinical and subclinical forms of mastitis, all of them lacked the efficacy to eliminate the associated etiological agent when used as a monotherapy. Further, research has to be directed towards the development of new therapeutic agents/techniques that can both replace conventional techniques and also solve the problem of emerging antibiotic resistance. The objective of the present review is to describe the etiological agents, pathogenesis, and diagnosis in brief along with an extensive discussion on the advances in the treatment and management of mastitis, which would help safeguard the health of dairy animals.

Antibiotic exposure and potential risk of depression in the Chinese elderly: a biomonitoring-based population study

OBJECTIVE

To examine the associations between urinary antibiotics from various sources and depression in the elderly using the biomonitoring method.

METHODS

In the current study, we investigated 990 elderly individuals (≥ 60 years old) from a community-based elderly cohort in West Anhui, China. The participants were interviewed by the Geriatric Depression Scale and self-developed questionnaires. A total of 45 antibiotics belonging to nine categories were screened in urine samples by the developed liquid chromatography electrospray tandem mass spectrometry method. Creatinine-corrected concentrations of antibiotics in urines were used to assess their exposure. Logistic regression analysis was employed to test the relationships between exposure to antibiotics and depression.

RESULTS

Compared to the control group, the multinomial logistic regression analyses showed the elderly exposed to higher concentrations of azithromycin (OR = 1.81, 95% CI: 1.09-3.00) and sulfaclozine (OR = 1.54, 95% CI: 1.05-2.28) had increased risks of depression, respectively. After categorizing the detected antibiotics, tetracyclines (OR = 1.48, 95% CI: 1.02-2.16) and veterinary antibiotics (VAs) (OR = 1.53, 95% CI: 1.06-2.20) were positively correlated with increased risks of depression. After stratified by sex, the VAs (OR = 2.04, 95% CI: 1.13-3.71) at higher concentrations were associated with elevated risks of depression in males, while the associations between depression and antibiotic exposures were observed in tetracyclines (OR = 1.74, 95% CI: 1.04-2.85) and all antibiotics (OR = 2.24, 95% CI: 1.01-2.94) at higher levels in females, respectively. Notably, after the stratification by age, the significant associations were mainly present in the subjects under the age of 70.

CONCLUSIONS

Our findings reveal that azithromycin, sulfaclozine, tetracyclines, and the VAs were significantly associated with elevated risks of depression in the elderly. Importantly, sex- and age-specific differences were observed in the associations between antibiotic exposures and depression.

Effects of Melatonin on Dairy Herd Improvement (DHI) of Holstein Cow with High SCS

Mastitis is a common disease in cows breeding. The milk quality will be significantly reduced with increased milk somatic cells, which often occurs in cows with mastitis. In this study, the influence of seasonal changes, age and lactation stages in the Dairy Herd Improvement (DHI) of cows was investigated. Then, the Dairy Herd Improvement (DHI) of cows with high somatic cell score (SCS) after melatonin treatment was systemically investigated. The results showed that melatonin significantly suppressed the milk somatic cell score under all of the tested conditions. The melatonin treatment also improved the milk nutritional value by reducing its fat but increasing its lactose and protein contents. The application of melatonin significantly improved the DHI. The beneficial effects of melatonin on DHI are likely attributed to the antioxidant and anti-inflammatory activities of melatonin.

Highly luminescent water-dispersed silicon quantum dots for fluorometric determination of oxytetracycline in milk samples

A fluorescent probe based on silicon quantum dots (SiQDs) was developed for the selective and sensitive detection of oxytetracycline (OTC) via the inner filter effect (IFE). The water-soluble fluorescent SiQD was synthesized based on the reaction of 3-Aminopropyltriethoxysilane (APTES) and sodium citrate as precursors by the one-pot hydrothermal process. The strong fluorescence emission of quantum dots (QDs) was obtained at 440 nm when excited at 350 nm and OTC had a broad absorption band between 200 and 400 nm. The excitation spectrum of SiQDs was completely overlapped with the absorption spectrum of OTC. The light at an excitation wavelength of QDs absorbed by OTC caused a decrease in fluorescence intensity with an increase in the concentration of OTC. Under optimal conditions, the linear concentration range was 0.92–9.2 µg mL1 with a detection limit (LOD; S/N = 3) of 0.19 µg mL ^-1 . The proposed method was applied to the determination of OTC in milk samples and satisfactory recoveries (98.8–100.5%) with low RSD % values (0.93–2.31%) were achieved. This simple, selective, sensitive, rapid, and cheap method can be used as a promising tool for OTC analysis in food safety.

Genotoxic impact of emerging contaminant amoxicillin residue on zebra fish (Danio rerio) embryos

The widest-spectrum, most-consumed β-lactam antibiotic amoxicillin (AMX) is used to treat bovine mastitis that is caused primarily by many bacteria. Excessive use of antibiotics can lead to established residual contamination of the milk even after pasteurization. The amount of antibiotic residue above Maximum Residue Limit (MRL) has a negative impact on both public health and the environment. Therefore, the objective of this study is to determine the concentration of amoxicillin residue (AMXR) in raw and pasteurized milk samples of cow suffered from mastitis, by the standard methods of HPLC compared to pure AMX drug and effect of the said residue on the developmental toxicity and genotoxicity of zebra fish at 72 hpf and 48 hpf embryo, respectively. Results obtained by HPLC showed that AMXR exhibits 574.89 and 250.75 times higher concentration in the raw and pasteurized milk than MRL in compare to pure AMX drug. This current study showed that AMXR decreased the body length and yolk sac region, while the pure AMX drug-treated group showed increased height and length of the yolk sac and shorter body length relative to the other groups. The Comet Assay measured the DNA damage caused by AMXR. The group where AMXR were applied showed the highest percentage of tail DNA and tail moment relative to other groups. So, here AMXR is considered as the genotoxic contaminant that is emerging and affect on public health.

QuEChERS and 96-well plate solid phase extraction for determination of vancomycin and norvancomycin in fish meat by UPLC-MS/MS

Vancomycin and norvancomycin are glycopeptide antibiotics for gram-positive bacteria infection, but indiscriminately used in aquaculture. In this study, a QuEChERS (quick, easy, cheap, effective, rugged, and safe)/96-well solid-phase extraction (SPE) plate method was used to extract vancomycin and norvancomycin in fish meat samples, and the drugs were further analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The parameters, such as the sorbent of cation exchange resin, the proportion of acetonitrile (15%) in extractant, the mobile phase of water (0.1% formic acid)/acetonitrile, were optimized. The method was validated in terms of linearity (0.9990-0.9994), LOD (0.51 μg·kg^-1), LOQ (1.73 μg·kg^-1), intra-dayprecision (<5.19%), inter-day precision (<6.30%), and recovery (86.7-98.6%). Finally, the method was successfully applied to contaminated and randomly collected samples. The results indicated that the proposed method meet the daily monitoring requirements for vancomycin and norvancomycin.

Chlortetracycline-Functionalized Silver Nanoparticles as a Colorimetric Probe for Aminoglycosides: Ultrasensitive Determination of Kanamycin and Streptomycin

Aminoglycosides (AMGs) have been extensively used to treat infectious diseases caused by Gram-negative bacteria in livestock and humans. A selective and sensitive colorimetric probe for the determination of streptomycin and kanamycin was proposed based on chlortetracycline-coated silver nanoparticles (AgNPs-CTC) as the sensing element. Almost all of the tested aminoglycoside antibiotics can rapidly induce the aggregation of AgNPs, along with a color change from yellow to orange/red. The selective detection of aminoglycoside antibiotics, including tobramycin, streptomycin, amikacin, gentamicin, neomycin, and kanamycin, with other types of antibiotics, can be achieved by ultraviolet (UV) spectroscopy. This developed colorimetric assay has ability to detect various AMGs using in-depth surface plasmon resonance (SPR) studies. With this determination of streptomycin and kanamycin was achieved at the picomolar level (pM) by using a UV-visible spectrophotometer. Under aqueous conditions, the linear range of the colorimetric sensor for streptomycin and kanamycin was 1000-1,1000 and 120-480 pM, respectively. The corresponding limit of detection was 2000 pM and 120 pM, respectively. Thus, the validated dual colorimetric and ratiometric method can find various analytical applications for the ultrasensitive and rapid detection of AMG antibiotics in water samples.