Solid phase extraction-surface enhanced Raman spectroscopy (SPE-SERS) test of antibiotic residues in Milk based on au@ MIL-101 NPs

Today, antibiotics are widely used for treatment and feed additives to enhance livestock growth. Antibiotic residues may be found in food of animal origin for various reasons, including ignoring the withdrawal period after treatment, overuse for animals, and contamination of feed with treated animals in animal products. Among animal products, dairy products have a special place in the human diet, and antibiotic residues in them have caused a great deal of concern among consumers. This systematic review and meta-analysis aimed to evaluate and compare studies conducted in Iran on antibiotic residues in dairy products during 2000-2022. In this review, 52 eligible studies were collected by searching the Scientific Information Database (SID), Magiran, Google Scholar, Science-Direct, Scopus, and PubMed using the English or Persian keywords such as an antibiotic or antimicrobial residue, Beta-lactam residue, Tetracycline residue, Sulfonamide residue, Chloramphenicol residue, Aminoglycosides residue, Macrolide residue, Quinolones residue, Milk, Raw milk, Pasteurized milk, UHT milk, Powder milk, Cheese, Yogurt, Butter, Cream, Doogh, Kashk, Ice cream, and Iran. According to the reviewed studies, the total prevalence of antibiotic residues in dairy products was 29% (95% CI: 15-43%). Among the seven evaluated antibiotic groups, most studies have been conducted on tetracycline, beta-lactam, and sulfonamide groups, with 16, 10, and 7 respectively, and the highest level of contamination with 663 ± 1540μg/l is related to tetracycline. Most studies on antibiotic dairy product residues in Iran with 12, 11, and 8 studies are associated with East Azarbaijan province, then Tehran and Khorasan Razavi respectively, and no study has been conducted in 11 provinces of the country. According to the studies, Gilan, Qazvin and Razavi Khorasan provinces had the highest amount of antibiotic residue in milk with an average value of 56.415 ± 33.354, 45.955 ± 4.179 and 45.928 ± 33.027, respectively. Most of the methods used in the studies to measure antibiotic residues in milk were the Copan test kit and the HPLC method, which were used in 19 and 14 studies, respectively. Studies have shown that the prevalence of antibiotic residue in dairy products in Iran is high, so applying an effective strategy and developing the necessary standards in this field to control milk quality is a public health necessity. The findings of this study show that further evaluation of fermented dairy products, especially non-fermented ones such as butter and cream, is needed to prevent adverse health reactions.

The current regulation in Mexico is explicit about the prohibition of the presence of antibiotic residues in raw cow's milk. Due to the impact of the presence of antibiotic residues in milk in the production of dairy products, some dairy companies have implemented their own programs to control antibiotic residues to avoid collection of contaminated material. The aim of this study was to analyze the results of the implementation of a program to control the presence of antibiotic residues in raw cow´s milk collected by a big local dairy industry. During the applications of this program, the frequency of contaminated milk containing the two main groups of antibiotics: β-lactams and tetracyclines, in 9 concentration facilities of a local dairy company, with an average size receiving 800,000- 1,000,000 L/day during 5 years. The antibiotic residue detection was performed using SNAP® Beta-Lactam Test and SNAP® Tetracycline Test simultaneously. During the first year, 222 tanks (2,955,538 L) were tested, of them 93 were positive for antibiotic residues (42.11%). In the fifth year, from 889 tanks containing 5,658,062 L only 13 were positive (1.46%), obtaining a reduction rate of 10.16% annual average. When the companies control the presence of inhibitor residues in the raw milk buy the milk, the farmers discard the contaminated milk; however, they sell it even with antibiotics when the buyers do not carry out controls, so this control measure becomes a solution. The results showed a significant decrease in contamination, being a useful solution to the problem of the appearance of antibiotic residues in milk in the raw material of the plant.

Objective:To analyze the presence of selective antibiotic residues (oxytetracycline, amoxicillin, and ciprofloxacin) in milk during the antibiotic treatment course, and to evaluate the thermal effect on antibiotics residual status in milk of antibiotic-treated cows.Materials and Methods:The raw fresh milk was collected from 18 lactating cows before antibiotics treatment, which were brought to the veterinary hospital and suffered from either mastitis, foot and mouth disease, fever, local wound, or non-specific diarrhea, and so on. Out of the 18 lactating cows, six were treated with oxytetracycline, six were treated with amoxicillin, and six were treated with ciprofloxacin parenterally. Milk samples were also collected at 2nd day during treatment and final collection was done after maintaining the withdrawal period. Since milk is heated before consumption, it was boiled at 100°C for 20 min to evaluate the thermal effect on antibiotics residual status. Thin-layer chromatography was done for screening of antibiotics residue before and after boiling of the milk.Results:At day 0 (before antibiotic treatment), no antibiotics (oxytetracycline, ciprofloxacin and amoxicillin) residue was detected in raw milk of antibiotic treated cows. In contrast, on day 2 (during antibiotic treatment), 100% raw milk samples showed positive for antibiotics residue. After boiling, all milk samples showed positive for such specific antibiotics residue. On the other hand, no antibiotics residues were detected on day 9, which indicates the completion of the withdrawal period of the respective antibiotic. The intensities of bands for antibiotic on thin-layer chromatography plate of antibiotic residues in milk samples (oxytetracycline, amoxicillin, and ciprofloxacin) expressed that the respective antibiotic residual status was higher in the boiled milk compare to the raw milk.Conclusion:Proper maintenance of withdrawal period after antibiotic treatment would minimize the risk of antibiotic residues in milk, and boiling does not change these specific antibiotics residual status in milk. Therefore, awareness regarding the proper maintenance of withdrawal period after antibiotic treatment in lactating cows is one of the best strategies that may positively reduce the risk of antimicrobial drugs residue in milk.

Uganda has experienced tick acaricide resistance in the livestock sector. With increase in incidence of tick-borne diseases (TBDs), use of antibiotics for control of TBDs and other opportunistic diseases has raisedserious concerns. The purpose of this study was to compare the farmers' tick control and antibiotic use practices on farms in regions of low (LARA) and high (HARA) tick acaricide resistance in Uganda, determine the prevalence of antibiotic residues in milk from both regions, and identify factors associated with antibiotic residues in milk. One representative district was selected from each region from which 10 farms were randomly selected. Delvotest SP-NT® test kit was used to detect antibiotic residues in milk. Half-body tick counts and acaricide efficacy tests were performed. Majority (70%) of HARA's respondents reported a corresponding increase in a monthly incidence of TBDs with an average of 3.2 cases of TBDs treated per farm compared to 0.2 cases in LARA. East Coast fever (ECF) was identified as the most common TBD in both regions, though cases of coinfection were more common in HARA. Half of HARA's respondents reported a corresponding increase in the use of antibiotics on their farms due to tick resistance compared to LARA. Antibiotics were the most used drugs on farms in both regions with oxytetracycline being the commonly used antibiotic. Ticks from HARA were resistant to deltamethrin, amitraz, and coformulation (chlorpyriphos and cypermethrin) while resistance against deltamethrin was confirmed in LARA. HARA farms had a significantly higher prevalence of antibiotic residues (21.25%) in raw milk than in LARA (4%) farms (p < 0.05). Acaricide resistance and practice of reading drug use instructions were significantly associated with antibiotic residues in milk at farm level. Overall, the study provides vital information linking acaricide resistance to antibiotic use practices, consequently leading to antibiotic residues in milk.

Milk and dairy products constitute essential nutritional sources for humans, particularly infants and children. From a public health perspective, it is therefore imperative that animal-derived milk remains free from residues that may pose risks to human health. This study aims to assess the presence of beta-lactam antibiotic residues in bovine milk. Between July and August 2023, a total of 180 raw cow’s milk samples were collected from six distinct locations (Ardahan, Göle, Çıldır, Hanak, Damal, and Posof) within the Ardahan region. The samples were obtained from milk collection tanks and cattle farms, with 15 samples collected from each location. Approximately 30 ml of milk per sample was placed in sterile plastic containers with lids, immediately transported to the laboratory, and stored at -20°C until analysis. The detection of beta-lactam antibiotic residues in the milk was performed using the ELISA method. The analysis confirmed the absence of beta-lactam antibiotic residues in all 180 raw cow’s milk samples. Consequently, this study indicates that raw cow’s milk from the Ardahan region is safe for human consumption. To ensure food safety and protect public health, it is recommended that training sessions be conducted to emphasise the importance of responsible antibiotic use and strict adherence to legal withdrawal periods for antibiotic-treated cattle. Additionally, the regular and systematic monitoring of antibiotic residues in milk is strongly advised.

Antimicrobial resistance (AMR) poses a significant global health challenge affecting food safety and development. Residues of antibiotics in food from animal sources, particularly milk, contribute to the development and spread of AMR, alter intestinal microbiota, and potentially lead to allergies, serious health conditions, and environmental and technological problems within the dairy industry. Therefore, this study investigated the residue levels of veterinary drugs from β-lactam antibiotics and tetracyclines in milk and milk products and assessed human health risks. Two hundred milk and milk product samples (pasteurized milk, sterile milk, soft white cheese, and processed cheese, 50 each) were collected from different hospitals in the State of Kuwait and screened for antibiotic residues using a microbial inhibition assay (Delvotest SP-NT) and high-performance liquid chromatography (HPLC). Delvotest SP-NT and HPLC analyses showed that 30, 28, 26, and 24% of the pasteurized milk, sterilized milk, white soft cheese, and processed cheese samples tested positive for antibiotic residues. Forty-eight milk and cheese samples were confirmed as positive by both methods, and six samples initially found to be negative by Delvotest SP-NT were confirmed as positive by HPLC. Multi-antibiotic residues were detected in five samples by using HPLC. The kappa coefficient (0.921; p < 0.0001) revealed complete concordance between the HPLC and Delvotest SP-NT results. Ampicillin was the most abundant residue in the positive samples (31.48%), ranging from 2.44 to 3.89 μg/L, with an overall mean concentration of 3.492 ± 0.094 μg/L, followed by tetracycline and oxytetracycline (27.78% each), ranging from 54.13 to 220.3 μg/L and from 41.55 to 160.7 μg/L, with mean concentrations of 129.477 ± 14.22 and 91.86 ± 9.92 μg/L, respectively. The amoxicillin levels in the samples (12/54; 22.22%) ranged from 3.11 to 5.5 μg/L, with an overall mean concentration of 3.685 ± 0.186 μg/L. The maximum concentrations of ampicillin, amoxicillin, and tetracycline were detected in processed cheese with mean concentrations of 3.89 ± 0.28 µg/L, 3.95 ± 0.15 µg/L, and 170.3 ± 0.27 µg/L, respectively. Pasteurized milk contained the maximum concentrations of oxytetracycline, with a mean concentration of 120.45 ± 0.25 µg/L. The tetracycline residues exceeded the standard maximum residue limits (MRLs; 100 µg/L) in 6% of both pasteurized and sterilized milk samples, and in 4% of processed cheese. Additionally, the oxytetracycline levels in pasteurized milk (6%) and amoxicillin levels in processed cheese (2%) were higher than the permitted MRLs (100 µg/L and 4 µg/L, respectively). Furthermore, the antibiotic residues detected in 12.5% (25/200) of the samples were close to standard permissible MRL limits for ampicillin (5%), amoxicillin and oxytetracycline (3% each), and tetracycline (1.5%). Hazard quotients, which compare the standard acceptable daily intake (ADI) to the estimated daily exposure (EDI), indicated that the overall risk associated with antibiotic residues in these dairy products is low. The EDI was lower than the ADI for the tested antibiotics, indicating an elevated safety margin. While the overall hazard quotients are low, the potential for the development of antibiotic resistance due to long-term exposure to low levels of antibiotics should be considered. Hence, strict regulations and enforcement are necessary to prevent excessive residue levels and to promote responsible antibiotic use in dairy production. Regular monitoring of antibiotic residues in dairy products is essential for ensuring consumer safety.

Background/Objectives: The deposition of antibiotic residues in animal source foods has become a global public health threat. This study aimed to assess antibiotic class residues in raw cow milk from smallholder dairy farms in Mbala and Kasama, Zambia. Methods: A cross-sectional study was conducted, in which 93 milk samples (54 from Mbala and 39 from Kasama) were randomly collected from lactating cows on 56 farms between May and June, 2025. The samples were analyzed using the Charm II assay for beta-lactams, tetracyclines, macrolides, sulfonamides, and aminoglycosides. A total of 100 mL of milk was collected in sterile plain tubes, placed in a cooler box with ice packs, and transported to the district laboratory's freezer and then delivered to the Central Veterinary Research Institute at (-18 to -20 °C), where they were stored at -20 °C. Statistical significance between districts was determined using Pearson's chi-square, and associations between a district and the occurrence of antibiotic residues in milk were evaluated using logistic regression. Data were analyzed using Stata 14.2 at a 95% confidence level (p = 0.05). Results: A total of 91.4% (n = 85) of samples had antibiotic residues above EU/MRLs, with mean positive samples being 0.91 ± 0.28 and a significant association between a district and residue occurrence (OR = 0.086; p = 0.025). Approximately 44.1% of the samples had multiple antibiotic residues. Approximately 82.1% of samples from Kasama and 98.1% from Mbala had antibiotic residues (p = 0.006). Approximately 68.8% of samples had sulphonamides, and 58.1% macrolides, indicating their widespread use. Tetracyclines were 12.9%, beta-lactams 9.7%, and aminoglycosides 2.2%. Conclusions: A majority of milk samples had antibiotic residues above EU/MRLs, raising public health threats and necessitating the development and implementation of policies.

Veterinary treatments, mainly antibiotics, used for therapeutic or prophylactic purposes in dairy farming can be the cause of the presence of antibiotic residues in milk. However, these residues constitute a major health concern for consumers. For the dairy industry, whose objective is to have a raw material suitable for processing, it is necessary to screen for antibiotic residues in milk at each collection. This study is based on two parts, a survey of seventy people (10 practicing veterinarians and 60 milk producers) to describe the main molecules of antibiotics used in dairy cattle farming in the two basins of Tienfala and Kasséla in the Koulikoro region, and a search for residues by Delvotest SP with confirmation of positive samples by liquid chromatography (HPLC). To this end, sixty (60) samples of raw milk were collected in two sampling campaigns per site carried out 15 days apart. All samples were analyzed using the Delvotest SP rapid detection of antibiotic residues in milk kit first before being analyzed by liquid chromatography (HPLC) for positive samples. The results of the surveys revealed the predominance of three pathologies within dairy herds: diarrhoea, mastitis and pulmonary infections with a combination of several antibiotics belonging to five (5) different families of antibiotics. Of the 60 samples submitted for analysis, 38 were found to be positive with Delvotest SP, i.e. a contamination rate of around 63.33%. Of the 38 samples positive to the rapid test, 26 responded positively to confirmation by liquid chromatography, i.e. a rate of 68.42% with mainly four antibiotics belonging to the families of β-lactams and tetracyclines. The results of the study effectively prove the effective presence of antibiotic residues in raw cow's milk from the mini-dairies of Kassela and Tienfala. They thus characterize current practices in the treatment of dairy cattle with antibiotics in the farming areas studied. Compliance with withdrawal periods with the elimination of milk from treated cows must be obtained by raising the awareness of producers by animal health professionals.

Antibiotic residue in milk has a negative impact on human health. The objective of this study was to determine the presence of doxycycline residues in fresh dairy milk and to evaluate its dietary intake to Indonesian population through milk consumption. Ninety milk samples were collected from the District of Malang (East Java Province) and sixty-six milk samples from Padang Panjang City (West Sumatera Province). All samples were analyzed for doxycycline residue using high-performance liquid chromatography (HPLC). The estimated daily intake (EDI) was determined by multiplying the mean concentration of antibiotics and the average daily milk consumption dividing it by the weight of population target. The occurrence of doxycycline residue obtained in raw milk samples was 36.67% for samples from Malang and 12.12% for samples from Padang Panjang. The range and average concentration for doxycycline residue in milk samples were 44.8-557.2 ng/g and 203.0 ng/g for samples from Malang and 14.2-64.5 ng/g and 30.1 ng/g for samples from Padang Panjang, respectively. Samples from Malang shows the highest EDI values of doxycycline both for adult, and children population and demonstrated the toxicological risk of consumption doxycycline together with the present other types or groups of antibiotics residue in milk or other types of foods. The results obtained show that, to prevent the negative effects of antibiotic residues on human health, the presence of antibiotic residues in raw dairy milk still needs to be monitored regularly.

Background: Antibiotics are commonly used in animal husbandry for medicinal, prophylactic and growth promotion purposes. Method: The prevalence of three groups of antibiotics; namely Gentamycin, Streptomycin and sulfonamides was studied in fresh milk available in five different study areas; namely Budhanilkantha, Dharmasthali, Tokha, Nepaltar and Gaushala from Kathmandu Valley of Nepal. The milk samples (n=100) were collected from local dairy collection centers of Kathmandu valley. Qualitative and semi-quantitative analysis with rapid screening kits revealed that 6% (n=6) samples were positive for antibiotic residues in the fresh milk for gentamycin, streptomycin and sulfonamide groups. Total 5% milk samples contained unidentified antibiotics residues. Sulfonamides residues were found to be highest 3% (n=3) followed by gentamycin 2% (n=2) and streptomycin 1% (n=1) with no any milk sample with multiple residues. Total 2 samples were positive in Dharmasthali, 2 in Gaushala, 1 in Nepaltar, 1 in Tokha and no positive samples from Budhanilkantha area. There was no statistical significant difference between study areas and commonly used antibiotics residues in milk samples (P is greater than 0.05). Conclusion: The antibiotic residues were found above the maximum residue limits that presented serious threat to consumer health and raised a serious concern regarding the implementation and monitoring of international regulations.

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.

Goat milk could be used to reduce malnutrition since it is highly nutritious, and many people in rural communities in South Africa rear small ruminants for survival. However, the risk of food contamination by antibiotic residues is one of the significant problems facing public health, and is a result of the irresponsible use of veterinary drugs. One hundred goat farmers were interviewed using a questionnaire, and raw milk samples from 266 goats were collected and analysed for the presence of antibiotic residues. Screening for amoxicillin, tetracycline, sulfamethazine, erythromycin, and streptomycin residues was done using the enzymelinked immunosorbent assay (ELISA) while high-performance liquid chromatography (HPLC) was carried out for confirmation. The questionnaire shows that all (100%) of the participants acknowledged the use of antibiotics on their goats and 99% of them were aware of the possibility of antibiotic residues in milk. ELISA results for residues of erythromycin, sulfamethazine and amoxicillin exceeded the Codex Alimentarius maximum residue levels (MRLs) in 94.7%, 82.3%, and 35.3% of analysed samples, respectively. Tetracycline was present in all (100%) analysed milk samples, and streptomycin was detected in 18.7% of samples; however, these results were below the recommended MRLs. The HPLC method confirmed the presence of streptomycin and tetracycline residues in 90% and 40% of the samples analysed. However, the concentrations were below the accepted MRL standards. Approximately 76.6% of samples exceeded the established MRL for sulfamethazine and 10% for erythromycin. Amoxicillin was not detected by the HPLC method. The results obtained in this study indicate a high level of contamination of goat milk with antibiotic residues, which may harm the health of the consumers.

ABSTRACTThe presence of antibiotic residues (ARs) in milk poses a significant challenge to public health and the dairy industry. This study presents the research trends on strategies to mitigate ARs in milk and dairy products, combining scientometric and systematic review approaches. Following the PRISMA guidelines, data from Web of Science, ScienceDirect, PubMed, Embase, AGRICOLA, and CAS yielded 49 original articles. Geographical analysis revealed a heterogeneous distribution, with Spain as the leading contributor. The analysis showed that heat treatment is the most studied mitigation strategy, reflecting its widespread industrial implementation. Crucially, a clear trend indicates the growth of emerging nonthermal technologies, such as pulsed electric field (PEF) and ozonation, driven by the need to preserve the nutritional and sensory attributes of milk. The most studied antibiotics belong to the tetracycline and penicillin classes, with oxytetracycline being most frequently investigated, followed by penicillin, tetracycline, ampicillin, chlortetracycline, cloxacillin, and amoxicillin. The findings confirm that no single strategy is universally effective. The results indicate that the future of ARs mitigation lies in the development of synergistic and combined approaches to achieve industrially viable, cost‐effective protocols that preserve product quality. This study highlights the need for future research focused on selective technologies and the assessment of by‐product toxicity, alongside the regulatory aspects for the application of these technologies.

Background and Aim:Antibiotics are widely used in animal production for treating the diseases and for preventing or increasing animal growth. The presence of antibiotic residues in milk is a public health problem. The aim of this study was to assess the use of antibiotic residues in raw milk from the dairy pool of Niamey in three farms (Toukounous, Kirkissoye, and Niamey) and three collection centers (Hamdallaye, Kollo, and Say).Materials and Methods:A direct interview (questionnaire) was used to collect data regarding the mode of use of antibiotics, the level of knowledge of farmers according to the withdrawal period, and a cross-sectional study was conducted on 192 samples of raw milk. The Delvotest® T was used to monitor antibiotic residues in milk. The data were analyzed using SAS and R software.Results:The most commonly used antibiotics were those from the family of tetracycline (86.7%) and from the family of beta-lactams (13.3%). Regarding the statements of farmers, the reasons why the farmers use antibiotics were the following: About 47% in case of prevention and treatment, 29% for treatment, 12% for prevention, and 12% for increase dairy production. Moreover, the farmers lacked the necessary information about withdrawal period. Screening of antibiotic residues was performed using a standardized biological test kit, the Delvotest®. In total, from 192 samples of raw milk, 19 (9.9%) were positive including ten from collection centers and nine from farms. This could lead to a risk of exposure when a consumer drinks locally produced raw milk.Conclusion:Raw milk supplied from the area of the study has a level of antibiotic residues, and the breeders have a low level of knowledge about the withdrawal period.

Educational interventions to address misconceptions about antibiotic residues in milk can alter consumer perceptions and may affect purchasing habits