State-of-the-art nanosensors and kits for the detection of antibiotic residues in milk and dairy products

Antibiotic resistance is increasingly seen as a future concern, but antibiotics are still commonly used in animals, leading to their accumulation in humans through the food chain and posing health risks. The development of nanomaterials has opened up possibilities for creating new sensing strategies to detect antibiotic residues, resulting in the emergence of innovative nanobiosensors with different benefits like rapidity, simplicity, accuracy, sensitivity, specificity, and precision. Therefore, this comprehensive review provides pertinent and current insights into nanomaterials-based electrochemical/optical sensors for the detection of antibitic residues (ANBr) across milk and dairy products. Here, we first discuss the commonly used ANBs in real products, the significance of ANBr, and also their binding/biological properties. Then, we provide an overview of the role of using different nanomaterials on the development of advanced nanobiosensors like fluorescence-based, colorimetric, surface-enhanced Raman scattering, surface plasmon resonance, and several important electrochemical nanobiosensors relying on different kinds of electrodes. The enhancement of ANB electrochemical behavior for detection is also outlined, along with a concise overview of the utilization of (bio)recognition units. Ultimately, this paper offers a perspective on the future concepts of this research field and commercialized nanomaterial-based sensors to help upgrade the sensing techniques for ANBr in dairy products.

The research progress on the impact of antibiotics on the male reproductive system

Antibiotics are extensively utilized in the livestock and poultry industry and can accumulate in animals and the environment, leading to potential health risks for humans via food and water consumption. Research on antibiotic toxicity, particularly their impact as endocrine disruptors on the male reproductive system, is still in its nascent stages. This review highlights the toxic effect of antibiotics on the male reproductive system, detailing the common routes of exposure and the detrimental impact and mechanisms of various antibiotic classes. Additionally, it discusses the protective role of food-derived active substances against the reproductive toxicity induced by antibiotics. This review aims to raise awareness about the reproductive toxicity of antibiotics in males and to outline the challenges that must be addressed in future research.

Antibiotic residues in pasteurised and Raw Cow's milk in Dhaka, Bangladesh

This study aimed to investigate antibiotic residues such as oxytetracycline, ciprofloxacin, enrofloxacin and levofloxacin, in both pasteurised and raw cow's milk. A method using high-performance liquid chromatography with a UV detector (HPLC-UV) was developed and validated following International Conference on Harmonization (ICH) guidelines for simultaneous detection and quantification of these residues. The technique demonstrated linearity, with r2 values ranging from 0.999 to 1.00 within the 1.3-15.0 μg ml-1 range for each antibiotic. Thirty cow's milk samples, raw and pasteurised, from Dhaka's local markets were analysed, revealing the presence of enrofloxacin and levofloxacin, while oxytetracycline was absent in all samples. Notably, pasteurised milk samples contained enrofloxacin, levofloxacin and oxytetracycline, with groups P6 and P7 exceeding the Maximum Residue Limit for enrofloxacin, levofloxacin and ciprofloxacin (121 µg l-1). This study emphasises antibiotic residues in milk, with a validated method holding promise for routine analysis in industries requiring simultaneous quantitation of multiple antibiotics.

Antibiotic Residues in Foods of Animal Origin in Cameroon: Prevalence, Consumers' Risk Perceptions, and attitudes

The use of antibiotics in food animals and the nonobservance of the withdrawal period might result in the accumulation and persistence of residues in foods. The contamination of foods by antibiotic residues might induce health risks including allergy, gastrointestinal dysbiosis, antimicrobial resistance, and cancer to consumers. Therefore, this study was initiated to investigate the presence of antibiotic residues in raw eggs, raw milk, and beef collected at the wholesale and retail points in the three major cities of Cameroon and consumers' perceptions of the risk of antibiotic residues in foods. Qualitative antibiotic residue kits (PremiTest® and Delvotest®) were used to screen 407 samples of foods collected in markets of three towns (Ngaoundéré, Yaoundé, and Douala) in Cameroon. A structured questionnaire was used to evaluate the knowledge and attitudes of 1462 consumers toward microbial drug residues in foods of animal origin. Prevalence of residues of 70.55%, 17.39%, and 69.63% for beef, eggs, and milk, respectively, was observed. More than 1/3 of the respondents believed that the consumption of contaminated foods with antibiotic residues is a risk to their health and thought that allergies and intoxication they often experience are related to the consumption of contaminated foods. Most of them showed their willingness to pay more to acquire quality foods, free from antibiotic residues.

Detection of antibiotic residues in groundwater with a validated multiresidue UHPLC-MS/MS quantification method

The occurrence of antibiotic residues in the environment has received considerable attention because of their potential to select for bacterial resistance. The overuse of antibiotics in human medicine and animal production results in antibiotic residues entering the aquatic environment, but concentrations are currently not well determined. This study investigates the occurrence of antibiotics in groundwater in areas strongly related to agriculture and the antibiotic treatment of animals. A multiresidue method was validated according to EU Regulation 2021/808, to allow (semi-)quantitative analysis of 78 antibiotics from 10 different classes: β-lactams, sulfonamides, tetracyclines, lincosamides, amphenicols, (fluoro)quinolones, macrolides, pleuromutilins, ansamycins and diaminopyrimidines using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method was used to test different storage conditions of these water samples during a stability study over a period of 2 weeks. Sulfonamides, lincosamides and pleuromutilins were the most stable. Degradation was most pronounced for β-lactam antibiotics, macrolides and ansamycins. To maintain stability, storage of samples at -18 °C is preferred. With the validated method, antibiotic residues were detected in groundwater, sampled from regions associated with intensive livestock farming in Flanders (Belgium). Out of 50 samples, 14% contained at least one residue. Concentrations were low, ranging from < LOD to 0.03 μg/L. Chloramphenicol, oxolinic acid, tetracycline and sulfonamides (sulfadiazine, sulfadoxine, sulfamethazine and sulfisoxazole) were detected. This study presents a new method for the quantification of antibiotic residues, which was applied to investigate the presence of antibiotic residues in groundwater in Flanders.

A workflow for the detection of antibiotic residues, measurement of water chemistry and preservation of hospital sink drain samples for metagenomic sequencing

BACKGROUND

Hospital sinks are environmental reservoirs that harbour healthcare-associated (HCA) pathogens. Selective pressures in sink environments, such as antibiotic residues, nutrient waste and hardness ions, may promote antibiotic resistance gene (ARG) exchange between bacteria. However, cheap and accurate sampling methods to characterize these factors are lacking.

AIMS

To validate a workflow to detect antibiotic residues and evaluate water chemistry using dipsticks. Secondarily, to validate boric acid to preserve the taxonomic and ARG ('resistome') composition of sink trap samples for metagenomic sequencing.

METHODS

Antibiotic residue dipsticks were validated against serial dilutions of ampicillin, doxycycline, sulfamethoxazole and ciprofloxacin, and water chemistry dipsticks against serial dilutions of chemical calibration standards. Sink trap aspirates were used for a 'real-world' pilot evaluation of dipsticks. To assess boric acid as a preservative of microbial diversity, the impact of incubation with and without boric acid at ∼22 °C on metagenomic sequencing outputs was evaluated at Day 2 and Day 5 compared with baseline (Day 0).

FINDINGS

The limits of detection for each antibiotic were: 3 μg/L (ampicillin), 10 μg/L (doxycycline), 20 μg/L (sulfamethoxazole) and 8 μg/L (ciprofloxacin). The best performing water chemistry dipstick correctly characterized 34/40 (85%) standards in a concentration-dependent manner. One trap sample tested positive for the presence of tetracyclines and sulphonamides. Taxonomic and resistome composition were largely maintained after storage with boric acid at ∼22 °C for up to five days.

CONCLUSIONS

Dipsticks can be used to detect antibiotic residues and characterize water chemistry in sink trap samples. Boric acid was an effective preservative of trap sample composition, representing a low-cost alternative to cold-chain transport.

Fluorescent and smartphone imaging detection of tetracycline residues based on luminescent europium ion-functionalized the regular octahedral UiO-66-NH2

Antibiotic residues cause extensive damage to food security, thus arousing serious concerns. Hence, rapid and sensitive detection of antibiotic residues is crucial to food safety. This study aimed to propose a portable, visual, intelligent and rapid method for tetracycline detection. We developed a ratiometric fluorescent sensor based on the Eu3+-functionalized regular octahedral UiO-66-NH2 material. The developed sensor could quantify tetracycline in the concentration range of 0.5-200 μM with a detection limit as low as 0.2 μM under the optimum conditions. Furthermore, the analytical results obtained using the designed sensor in the actual samples were basically consistent with those obtained using high-performance liquid chromatography. Based on these achievements, a smartphone application-integrated fluorescent testing paper was designed for facile, intelligent, and visual detection of tetracycline. The integrated portable sensor not only saved cost and time for testing but also provided a forward-looking approach to fast, sensitive detection of antibiotic residues.

Similarities of Geobacillus bacteria based on their profiles of antimicrobial susceptibility in milk samples

The genus Geobacillus is composed of thermophilic bacteria that exhibit diverse biotechnological potentialities. Specifically, Geobacillus stearothermophilus is included as a test bacterium in commercial microbiological inhibition methods, although it exhibits limited sensitivity to aminoglycosides, macrolides, and quinolones. Therefore, this article evaluates the antibiotic susceptibility profiles of five test bacteria (G. stearothermophilus subsp. calidolactis C953, Geobacillus thermocatenulatus LMG 19007, Geobacillus thermoleovorans LMG 9823, Geobacillus kaustophilus DSM 7263 and Geobacillus vulcani 13174). For that purpose, the minimum inhibitory concentrations (MICs) of 21 antibiotics were determined in milk samples for five test bacteria using the radial diffusion microbiological inhibition method. Subsequently, the similarities between bacteria and antibiotics were analyzed using cluster analysis. The dendrogram of this multivariate analysis shows an association between a group formed by G. thermocatenulatus and G. stearothermophilus and another by G. thermoleovorans, G. kaustophilus and G. vulcani. Finally, future microbiological methods could be developed in microtiter plates using G. thermocatenulatus as test bacterium, as it exhibits similar sensitivities to G. stearothermophilus. Conversely, G. vulcani, G. thermoleovorans and G. kaustophilus show higher MICs than G. thermocatenulatus.

Impacts of net cages on pollutant accumulation and its consequence on antibiotic resistance genes (ARGs) dissemination in freshwater ecosystems: Insights for sustainable urban water management

There has been increasing interest in the role of human activities in disseminating antibiotic-resistance genes (ARGs) in aquatic ecosystems. However, the influence of pollutant accumulation on anthropogenic pollutant-ARG synergistic actions is limited. This study explored the association of net cages with the propagation of anthropogenic pollutants and their consequences for influencing the enrichment of ARGs using high-throughput metagenomic sequencing. We showed that net cages could substantially impact the ecology of freshwater systems by enhancing i) ARG diversity and the tendency for ARG-horizontal gene transfer and ii) the overlap of mobile genetic elements (MGEs) with biocide-metal resistance genes (BMRGs) and ARGs. These findings suggested that the cotransfer of these three genetic determinants would be favored in net cage plots and that nonantibiotic factors such as metal(loid)s, particularly iron (Fe), displayed robust selective pressures on ARGs exerted by the net cage. The resistome risk scores of net cage sediments and biofilms were higher than those from off-net cage plots, indicating that the net cage-origin antibiotic resistome should be of great concern. The combination of deterministic and stochastic processes acting on bacterial communities could explain the higher ARG variations in cage plots (8.2%) than in off-cage plots (3.4%). Moreover, MGEs and pollutants together explained 43.3% of the total variation in ARG communities, which was higher than that of off-cage plots (8.8%), considering pollutants, environmental variables, MGEs, and assembly processes. These findings will inform the development of policies and guidelines to more effectively limit the spread of antimicrobial resistance and achieve the goal of sustainability in freshwater systems in urban areas.

Current analytical strategies for the determination of quinolone residues in milk

Quinolones are potent antibacterial drugs extensively utilized for treating bacterial infections in poultry. However, the presence of quinolone antibiotic residues in milk is a matter of concern due to potential health risks and adverse effects on milk quality. This review provides an overview of current analytical strategies for the determination of quinolone residues in milk. Various sample preparation techniques, such as liquid-phase extraction, solid-phase extraction and QuEChERS, are discussed, along with detection methods including instrument-based detection, immune-based detection, and microbial detection. The advantages and limitations of each method are highlighted, as well as their applicability in different stages of milk production. Additionally, recent advancements in sample preparation and detection methods are presented. This comprehensive review aims to contribute to the development of accurate and reliable methods for the detection of quinolone residues in milk, ensuring the safety and quality of dairy products.

Smartphone-based pH responsive 3-channel colorimetric biosensor for non-enzymatic multi-antibiotic residues

Antibiotic residues in animal-derived food pose a risk to food safety and human health. Here, a smartphone-based pH-responsive 3-channel colorimetric biosensor is constructed for rapid detection of non-enzymatic multi-antibiotic residues in milk. In this system, a magnetic separation and enrichment approach is designed to specifically capture different antibiotic residues in complex environment. Indicators loaded on polydopamine-silver nanoparticles with excellently pH responsive visualization properties are utilized to ensure the high sensitivity of detection system. Moreover, smartphones are introduced to fulfill the demand for portable and on-site inspection of practical applications. It achieves simultaneous detection of oxytetracycline, kanamycin and streptomycin in the linear range of 1-105 pg/mL with detection limits of 0.085, 0.168, and 0.307 pg/mL, respectively. The practicality of the reported multi-antibiotic residues detection system is successfully demonstrated and evaluated challenging milk samples. Therefore, this system demonstrates the wide applications in multi-antibiotic residue analysis and food safety guarantee.

Oxytetracycline changes the behavior of zebrafish larvae by inhibiting NMDA receptors

Oxytetracycline (OTC), a tetracycline antimicrobial, is one of the antimicrobial drugs frequently used in the aquaculture and livestock industries. Due to its extensive usage and emissions, OTC has been identified as a significant new emerging pollutant (EP) in a number of environments. OTC frequently causes toxic effects on the central nervous system, but it can be challenging to monitor, and it is still unclear how these toxicities are caused. We used bioinformatic analysis techniques to screen for OTC targets and discovered that NMDA receptors are potential targets of OTC neurotoxicity. To confirm this finding, we exposed zebrafish embryos to 5 mg/L OTC-containing rearing water from 2-hour post fertilization (hpf) to 8-day post fertilization (dpf), performed spontaneous movement and light-dark stimulation assays at 6 and 8 dfp, and discovered that OTC inhibited locomotor activity and attenuated anxiety-like responses in zebrafish larvae. Meanwhile, the qPCR and immunofluorescence staining results suggested that OTC inhibited the expression of multiple subtypes of NMDA receptors (grin1a, grin1b, grin2bb, grin2ca) and induced apoptosis in the brains of zebrafish embryos. Simultaneous administration of NMDA, an NMDA receptor agonist, completely antagonized the inhibitory neurobehavioral changes in zebrafish larvae, as well as the downregulation of N-methyl-D-aspartate (NMDA) receptor expression and apoptosis in the embryonic brains caused by OTC exposure. In conclusion, OTC exhibited significant inhibitory neurobehavioral toxicity in zebrafish larvae during early development, which may be dependent on its suppression of NMDA receptor activity and expression. Furthermore, OTC-induced neurodevelopmental toxicity may be associated with NMDA receptor-regulated neuronal apoptosis.

Sulfonamides and β-lactam antibiotic residues and human health risk assessment in commercial chicken meat sold in Nairobi City, Kenya

The use of antibiotic pharmaceuticals in chicken husbandry has risen steadily over time. Antibiotic residues in chicken meat poses risks to human health in addition to their contribution to the advancement of antibiotic resistance. Despite the increased use of antibiotics in chicken farming in Kenya, assessments of the residues and human exposure have not been conducted. In this study, the sulfonamides (SAs); sulfapyridine (SPD), sulfadiazine (SDZ) and sulfamethazine (SMZ) and the β-lactams (βLs); ampicillin (AMP), penicillin G (PEG) and amoxicillin (AMX) were determined in three chicken meat types; ex-layers, broilers, and indigenous meat marketed in Nairobi City, Kenya. Residual SAs ranged from 0.1 to 154.4 μg kg-1, with SPD recording the highest concentration in ex-layers' chicken meat samples. A range of 19.7 to 309.0 μg kg-1of BLs was found, where the highest amount represented AMX in ex-layers. Mean AMX contents in all chicken types, and AMP in broilers were above the Maximum Residue Limits (MRLs). For SAs, only SPD mean content was above MRL in ex-layers. Human health risks from exposure to antibiotic-contaminated chicken meat was evaluated using % ADI. All tested βLs were of no risk (<1% ADI) to human health. SPD and SDZ posed considerable risk (1-5% ADI) in some chicken meat, whereas SPD in ex-layers' chicken meat posed distinctive risk (>5% ADI) to children. Considering the co-occurrence of different types of antibiotics in same samples, obtained MRLs and % ADI (for some of the antibiotics) are indicative of potential human health risks. Information is valuable in provoking response from concerned agencies and fostering activities that advocate for judicious use of antibiotics.

Current Trends in Nanomaterials-Based Electrochemiluminescence Aptasensors for the Determination of Antibiotic Residues in Foodstuffs: A Comprehensive Review

Veterinary pharmaceuticals have been recently recognized as newly emerging environmental contaminants. Indeed, because of their uncontrolled or overused disposal, we are now facing undesirable amounts of these constituents in foodstuff and its related human health concerns. In this context, developing a well-organized environmental and foodstuff screening toward antibiotic levels is of paramount importance to ensure the safety of food products as well as human health. In this case, with the development and progress of electric/photo detecting, nanomaterials, and nucleic acid aptamer technology, their incorporation-driven evolving electrochemiluminescence aptasensing strategy has presented the hopeful potentials in identifying the residual amounts of different antibiotics toward sensitivity, economy, and practicality. In this context, we reviewed the up-to-date development of ECL aptasensors with aptamers as recognition elements and nanomaterials as the active elements for quantitative sensing the residual antibiotics in foodstuff and agriculture-related matrices, dissected the unavoidable challenges, and debated the upcoming prospects.

The development of an integrated environment-human risk approach for the prioritisation of antibiotics for policy decisions

Environmental contamination with antibiotic residues has caused significant concern. Antibiotics are continually emitted into the environment which potentially threatens environmental and human health, particularly, the risk in the development of antibiotic resistance. A list of priority antibiotics in the environment is essential for eco-pharmacovigilance and policy decisions. This study developed a prioritisation system of antibiotics based on their integrated environmental (resistance and ecotoxicity) and human health (resistance and toxicity) risks, considering various aquatic environmental compartments. Data obtained by conducting a systematic review of the literature of antibiotic residues in various aquatic environmental compartments in China was used as an example. The list of priority antibiotics was created by ranking the antibiotics in descending order, based on the risk scores of their a) overall risk, (b) antibiotic resistance risk to environment, (c) ecotoxicity risk, (d) overall environmental risk, (e) antibiotic resistance risk to human health, (f) toxicity risk to human health and (g) overall human health risk. Ciprofloxacin posed the greatest risk and chloramphenicol posed the least risk. The output from this research can be used to implement eco-pharmacovigilance and to develop targeted policies which would prevent / minimise the environmental and human health risks from antibiotic residues. The use of this list of priority antibiotics will allow for a country / region / setting to (a) optimise the use of antibiotics and their prescribing practices, (b) create effective monitoring and mitigation strategies, (c) minimise the discharge of antibiotic residues and (d) focus research efforts.

Amino-functionalized Al-MOF modulated TpTt-COF with dual-emission for fluorescent and optosmart detecting tetracycline in food samples

Tetracycline residues in animal-derived food pose serious harm to human health, making it demanded to develop simple and sensitive method for detecting tetracycline. Herein, a dual-emission synchronous response fluorescence probe is reported based on amino-functionalized Al-MOF modulated TpTt-COF (donate as NMT). NMT exhibits excellent dual-emission at 455 and 575 nm under single excitation. Tetracycline is sensitively detected through quenching the dual-emission of NMT. NMT specifically recognizes tetracycline through intermolecular hydrogen bonding between -OH/-NH₂ of tetracycline and deprotonated O^-/-NH-/CN of NMT. A calibration curve is built between the fluorescence ratio and the tetracycline concentration with a detection limit of 0.014 μmol/L. NMT is employed to detect tetracycline in milk, pork and chicken, and displays satisfactory recoveries of 94.39-105.67%, respectively. The optosmart sensor based on NMT and smartphone has been constructed for visually detecting tetracycline. This method provides routes to construct MOF-COF fluorescence probes and has good prospects in food analysis.

The impact of antibiotic residues on resistance patterns in leek at harvest

When crops are cultivated on fields fertilized with animal manure, the risk exists that plants may take up antibiotic residues and may be exposed to antibiotic resistance genes and antibiotic resistant bacteria. During cultivation in a greenhouse pot experiment, leek (Allium porrum) was fertilized with either pig slurry or mineral fertilizer and exposed to either no antibiotics, doxycycline (10,000 μg/kg manure), sulfadiazine (1000 μg/kg manure), or lincomycin (1000 μg/kg manure). At harvest, 4.5 months later, lincomycin, sulfadiazine or doxycycline were not detected in any of the leek samples nor in their corresponding soil samples. Further, antimicrobial susceptibility testing was performed on 181 Bacillus cereus group isolates and 52 Pseudomonas aeruginosa isolates from the grown leek. For the B. cereus group isolates, only a small shift in MIC50 for lincomycin was observed among isolates from the lincomycin and control treatment. For P. aeruginosa, only in the setup with doxycycline treatment a higher MIC50 for doxycycline was observed compared to the control, specifically the isolates selected from growth media supplemented with 8 mg/L doxycycline. Nine antibiotic resistance genes (tet(B), tet(L), tet(M), tet(O), tet(Q), tet(W), erm(B), erm(F) and sul2) were investigated at harvest in the leek and soil samples. In the leek samples, none of the antibiotic resistance genes were detected. In the soil samples fertilized with pig slurry, the genes erm(B), erm(F), tet(M), sul2, tet(W) and tet(O) were detected in significantly higher copy numbers in the lincomycin treatment as compared to the other antibiotic treatments. This could be due to a shift in soil microbiota induced by the addition of lincomycin. The results of this study indicate that consumption of leek carries a low risk of exposure to antibiotic residues or antibiotic resistance to doxycycline, sulfadiazine or lincomycin.

A novel label-free dual-mode aptasensor based on the mutual regulation of silver nanoclusters and MoSe(2) nanosheets for reliable detection of ampicillin

Current methods for the rapid detection of trace antibiotics in the environment remains problems of low accuracy and false negative or false positive, making the development of fast, and accurate, and reliable methods for antibiotic testing a major challenge that needs to be addressed. Herein, we developed a novel label-free colorimetric and fluorescent dual-mode aptasensor assembled by the strong interaction of layered MoSe₂ nanosheets (MoSe₂ NSs) with ampicillin (AMP) aptamer functionalized silver nanoclusters (Apt-AgNCs) that specifically bind AMP to allow the sensitive and selective detection of AMP. Apt-AgNCs could be adsorbed on the surface of MoSe₂ NSs via van der Waals force to form a nanocomposite, Apt-AgNCs/MoSe₂ NSs. Interestingly, Apt-AgNCs/MoSe₂ NSs act together to construct dual mode aptasensor through modulation of the intrinsic peroxidase activity of MoSe₂ NSs and the fluorescence of Apt-AgNCs. In the presence of AMP, Apt-AgNCs could specifically bind AMP, triggering desorption from the MoSe₂ NSs surface, leading to a decrease in the peroxidase activity of the system with the recovery in Apt-AgNCs fluorescence. The dual-signal aptasensor exhibited good linear colorimetric and fluorescence responses in the AMP concentration ranges of 0.115-2.00 μM and 6-100 nM, respectively. Furthermore, the aptasensor was successfully measured AMP levels in commercially-bought milk and lake water with satisfactory results. Unlike single-signal aptasensors, the constructed dual-signal aptasensor could not only improve the detection precision, but also reduce the false positive or false negative results. These promising results suggest that the dual-readout strategy as demonstrated is general mode for the detection of other antibiotics or compounds using various aptamers functionalized AgNCs in concert with MoSe₂ NSs.

Screening of antibiotic residues in raw bovine milk in Lombardy, Italy: Microbial growth inhibition assay and LC-HRMS technique integration for an accurate monitoring

Antibiotic residues in food of animal origin is a great concern for public health worldwide in terms of antibiotic resistance development, potential allergic reactions and disruption of intestinal flora equilibrium. In this study the presence of antibiotic residues in raw bovine milk samples collected from farms located in Lombardy region in Italy from 2018 to 2022 was assessed in the context of the national milk quality payment system. Samples were screened with microbiological growth inhibition test Delvotest ® SP NT and a very low positivity rate ranging from 0.1% to 0.07% over the four years was determined. A total of 79 positive samples were further analysed by LC-HRMS screening technique to confirm positivity and detect the specific antibiotic compound contaminating the sample. The β-lactam antibiotics resulted to be the most frequently detected, with the penicillin G being the most abundant compound. The data suggested that low levels of antibiotic contamination are consistently maintained over the last four years and the integration of the techniques used in this study is a valuable tool for a deep and precise monitoring of antibiotic residues in milk.

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.

Occurrence and ecological risk assessment of antibiotic residues in urban wastewater discharged into the coastal environment of the Persian Gulf (the case of Bandar Abbas)

This is the first attempt to detect antibiotic residues released into the Persian Gulf marine environment. In particular, this study quantifies and assesses the ecological risks of amoxicillin (AMX) and azithromycin (AZM) residues in wastewater outfalls from Bandar Abbas, one of the major coastal cities in southern Iran. The wastewater effluent samples were collected from two main wastewater discharging stations, Gursuzan and Suru, between December 2020 and February 2021. High-performance liquid chromatography (HPLC) analysis revealed the average concentration (± 95% CL) of AMX were 460 ± 230.0 μg L^-1 and 280 ± 100.6 μg L^-1 in Gursuzan and Suru stations. Mean AZM concentrations were also 264 ± 10.59 μg L^-1 and 295 ± 89.75 μg L^-1 in these stations, respectively. Pooled data indicated that there are 335.17 ± 105.11 and 288.17 ± 37.94 μg of AMX and AZM residues in the wastewater per liter. The values of potential ecological risk, hazard quotient (HQ), were extensively above 10 (AMX: 90,586.5 and AZM: 5541.7) which suggest that these substances have a high health risk for the ecosystem and public. Given that Bandar Abbas wastewater treatment plant (WWTP) outlets are discharged at about 500 to 700 L s^-1, the daily maximum potential AMX and AZM released were estimated to be 19.05 (± 0.283) × 10³ and 14.74 (± 0.113) × 10³ g day^-1, respectively (α = 0.05). Our findings show that there is a concerning volume of antibiotic residues released into the northern Persian Gulf, and hence urgent policies and actions are necessary to reduce this pollution.

Synthetic organic antibiotics residues as emerging contaminants waste-to-resources processing for a circular economy in China: Challenges and perspective

Synthetic antibiotics have been known for years to combat bacterial antibiotics. But their overuse and resistance have become a concern recently. The antibiotics reach the environment, including soil from the manufacturing process and undigested excretion by cattle and humans. It leads to overburden and contamination of the environment. These organic antibiotics remain in the environment for a very long period. During this period, antibiotics come in contact with various flora and fauna. The ill manufacturing practices and inadequate wastewater treatment cause a severe problem to the water bodies. After pretreatment from pharmaceutical industries, the effluents are released to the water bodies such as rivers. Even after pretreatment, effluents contain a significant number of antibiotic residues, which affect the living organisms living in the water bodies. Ultimately, river contaminated water reaches the ocean, spreading the contamination to a vast environment. This review paper discusses the impact of synthetic organic contamination on the environment and its hazardous effect on health. In addition, it analyzes and suggests the biotechnological strategies to tackle organic antibiotic residue proliferation. Moreover, the degradation of organic antibiotic residues by biocatalyst and biochar is analyzed. The circular economy approach for waste-to-resource technology for organic antibiotic residue in China is analyzed for a sustainable solution. Overall, the significant challenges related to synthetic antibiotic residues and future aspects are analyzed in this review paper.

A competitive colorimetric aptasensor for simple and sensitive detection of kanamycin based on terminal deoxynucleotidyl transferase-mediated signal amplification strategy

We developed a rapid and sensitive colorimetric biosensor based on competitive recognition between kanamycin (KAN), magnetic beads-kanamycin (MBs-KAN) and aptamer and terminal deoxynucleotidyl transferase (TdT)-mediated signal amplification strategy. In the absence of KAN, aptamers recognize MBs-KAN. TdT can amplify oligonucleotides to the 3'-OH ends of aptamers, with biotin-dUTP being embedded in the long single stranded DNA (ssDNA). Then the assay produced visual readout due to the horseradish peroxidase (HRP)-catalyzed color change of the substrate after the linkage between biotin and streptavidin (SA)-HRP. In the presence of KAN, however, aptamers tend to bind free KAN rather than MBs-KAN. In this case, aptamers are isolated by magnetic separation, resulting in the failure of signal amplification and catalytic signals. This competitive colorimetric sensor showed excellent selectivity toward KAN with the limit of detection (LOD) as low as 9 pM. And recovery values were between 93.8 and 107.8% when spiked KAN in milk and honey samples.

Impact of fertilization with pig or calf slurry on antibiotic residues and resistance genes in the soil

Antibiotic residues and antibiotic resistance genes can enter the environment via fertilization with calf and pig manure. In a longitudinal study, nine antibiotic resistance genes (tet(B), tet(L), tet(M), tet(O), tet(Q), tet(W), erm(B), erm(F) and sul2) and 56 antibiotic residues were investigated in 288 soil samples and 8 corresponding slurry samples from 6 pig farms and 2 veal farms using qPCR and LC-MS/MS, respectively. A significant increase in gene copy number of tet(M), erm(B), erm(F) and sul2 was observed in all the soil layers between sampling times prior to (T1) and 2-3 weeks after fertilization (T3). Tet(B), tet(Q) and tet(L) were least abundant in the soil among the genes tested. From 7 classes of antibiotics, 20 residues were detected in soil and slurry using an optimized and validated extraction method. Flumequine was detected in all soil samples in concentrations below 100 μg/kg despite being detected in only half of the corresponding slurry samples. Doxycycline, oxytetracycline, lincomycin and sulfadiazine were also frequently detected in concentrations ranging from 0.1 μg/kg to 500 μg/kg and from 2 μg/kg and 9480 μg/kg in soil and slurry, respectively. Furthermore a positive association between the presence of antibiotic residues (total antibiotic load) and antibiotic resistance genes in soil was found. One possible explanation for this is a simultaneous introduction of antibiotic residues and resistance genes upon application of animal slurry.

Development and validation of liquid chromatography method for simultaneous determination of multiclass seven antibiotic residues in chicken tissues

Background

Antibiotics are routinely used on poultry for therapy and prevention of diseases and to enhance animal growth. The objective of this study was to develop and validate a sensitive and reliable liquid chromatography with UV detection (LC-UV) method for the simultaneous determination of seven multiclass antibiotic residues (amoxicillin, ampicillin, penicillin, sulfamethoxazole, gentamicin, ciprofloxacin, and erythromycin) in chicken tissues.

Methods

The liquid chromatography method with UV detection was optimized for complete separation of the seven selected antibiotic compounds with reversed phase and isocratic elution using Hypersil BDS-C18 (3 µm, 100 mm × 4 mm) column. The mobile phase consisted a ratio of 0.05 M Na₂HPO₄, acetonitrile and methanol (70:10:20), at UV absorption wavelength of 230 nm. The column thermostat was set at 40 °C, the mobile phase flow rate was 1 mL min⁻¹, and the injection volume was 20 μL.

Results

All the seven standard compounds were eluted within 14 min. The results for: linearity, precision, sensitivity, accuracy, specificity, decision limit (CCα), detection capability (CCβ), suitability and method robustness were validated according to the criteria of Commission Decision 2002/657/EC guidelines. Calibration plot correlation coefficients ranged from 0.9983 to 0.9998 and the percent relative standard deviations for repeated analysis were below 5% indicating acceptable method precision. The limits of detection (LODs) and quantification (LOQs) ranged from 0.098–0.255 μg kg⁻¹ to 0.297–0.574 μg kg⁻¹, respectively. The accuracy study yielded recoveries in the ranges 98.1–107% for the pure compounds and 94.0–102% for the spiked drug free chicken tissue samples.

Conclusions

The method was found to be appropriate for simultaneous determination of five different classes of seven antibiotic residues in chicken tissues. Furthermore, this is the first instance for the simultaneous determination of seven multiclass, multi-residues analysis using LC-UV from chicken tissue samples. This is a cost-effective and alternative method with simple instrumentation approach for laboratories that lack highly specialized state-of-the-art instrumentation.

Efficient, rapid and simple adsorption method by polydopamine polystyrene nanofibers mat for removal of multi-class antibiotic residues in environmental water

Polydopamine polystyrene nanofibers mat (PDA-PS NFsM) was prepared as an adsorbent for the simultaneous removal of multiple antibiotic residues in environmental water for the first time. PDA-PS NFsM can directly be used to adsorb 18 antibiotic residues belonging to 8 classes without any pretreatment of water samples. The adsorption process was completed within 5 min. All antibiotics could be removed at the same time, and the removal rate of each target was above 85%. Moreover, the used PDA-PS NFsM can be easily separated from the environmental water by taking out directly, and can be reused for 10 times after simple regeneration. The thermodynamic and kinetic properties of PDA-PS NFsM adsorption of antibiotic residues were further investigated consequently. It was found that the adsorptions of PDA-PS NFsM to the targets were spontaneous and endothermic process (ΔG<0, ΔH>0, ΔS>0). The results of adsorption kinetic experiments illustrated that the adsorption process was rapid, the adsorption equilibrium of which can be reached in 5 min. Adsorption isotherm experiments proved that the adsorption process of PDA-PS NFsM was consistent with Langmuir adsorption (R² > 0.994), and the maximum adsorption capacity of PDA-PS NFsM towards all targets were 123.76 mg g^-1. The developed method is rapid and simple, and can efficiently adsorb and remove a variety of antibiotics in environmental water, which has good practical application prospect.

Dynamics and removal mechanisms of antibiotic and antibiotic resistance genes during the fermentation process of spectinomycin mycelial dregs: An integrated meta-omics study

Antibiotic mycelial dregs (AMDs) have been listed as industrial hazardous wastes. With the aim of reducing the environmental risk, the integrated-omics and qPCR approaches were used to reveal the dynamics and removal mechanisms of antibiotic and antibiotic resistance genes (ARGs) during the fermentation of different spectinomycin mycelial dregs (SMDs). The results showed that the removal efficiency of antibiotic in the fermentation of high moisture SMDs reached up to 98%. The high abundance of aadA1 gene encoded by Streptomyces, Lactobacillus, and Pseudomonas was associated with the efficient degradation of spectinomycin, and the inactivating enzymes secreted by degradative bacteria were identified. Furthermore, the dominant microbiota was impacted by moisture content significantly under high temperature environments. In the fermentation of low moisture SMDs, Saccharopolyspora was the dominant microbiota which secreted S8 endopeptidase, M14, M15, S10, S13 carboxypeptidases, M1, M28, S15 aminopeptidases, and antioxidant enzymes, while in the fermentation of high moisture SMDs, Bacillus and Cerasibacillus were dominant genera which mainly secreted S8 endopeptidase and antioxidant enzymes. The abundance of ARGs and mobile genetic elements decreased significantly at thermophilic phase, with maximum drops of 93.7% and 99.9%, respectively. Maintaining moisture content below 30% at the end phase could prevent the transmission of ARGs effectively.

Determination of antibiotic residues in bovine milk by HPLC-DAD and assessment of human health risks in Northwestern Himalayan region, India

Antibiotic residues in milk affects economics of dairy industry and poses health risks to consumers. This study aimed to assess health risks associated with presence of antibiotics in 173 raw and pasteurized milk sampled from northwestern Himalayan state of India. The oxytetracycline and amoxicillin were quantitatively analyzed using validated HPLC-DAD. Methods were selective and linear (R² > 0.99) with decision limit and detection capability of 1.4 and 0.9 µg/kg and 2.5 and 1.5 µg/kg for oxytetracycline and amoxicillin, respectively. Recoveries ranged from 88-98% with relative standard deviation < 10%. Oxytetracycline and amoxicillin were detected in 8.1% and 1.2% samples, with 1.7% and 1.2% samples exceeding the tolerance limits, respectively. Health risk assessment revealed that estimated daily intakes of antibiotics through milk were lower than acceptable daily intakes (ADI). However, children might receive 9-21% of determined ADI through milk consumption only. Therefore, continuous, sub-therapeutic and long term exposures of antibiotics can pose health risk to consumers. Hence, current findings elucidate the need for vigilant monitoring of antibiotics accompanied by educational programs to farmers for adopting good husbandry practices and adherence to withdrawal periods to meet the expectations of food safety and safeguarding human health.

SUPPLEMENTARY INFORMATION

The online version of this article contains supplementary material available at (10.1007/s13197-021-04988-8).

Detection and quantification of multiclass antibiotic residues in poultry products using solid-phase extraction and high-performance liquid chromatography with diode array detection

This article describes the initial study on the simultaneous determination of multiclass antibiotic residues in imported and local frozen poultry specimens, including turkey gizzard and muscle tissues, and chicken muscle tissues, commonly consumed in Ogun State, Nigeria. Minced tissues were treated with phosphate buffer adjusted to pH 7 that was cleaned using C18 SPE-column (Supelclean™) cartridge. For the determination of six antibiotic residues including fluoroquinolones, sulfonamides, and macrolides, a solid-phase extraction method was used, followed by extract analysis using high-performance liquid chromatography–diode array detection (HPLC–DAD). The coefficient of determination (R²) for the external standards for all the analytes ranged between 0.963 and 0.999. The limit of detection (LOD) and quantification (LOQ) ranged between 5.37 – 55.4 μg/kg, and 17.9–185 μg/kg, respectively. Enrofloxacin, sulfadimethoxine, sulfamerazine, and tylosin showed high concentration levels in the frozen poultry beyond acceptable maximum residue limits (MRLs). The six drugs considered in this study were present at higher concentrations in domestic chicken tissues than the permissible level. This suggests that farmers do not observe the cessation period before poultry birds previously treated with antibiotics are sold to consumers thus exposing them to potentially hazardous antibiotic residues.

Rapid determination of multi-antibiotic residues in honey based on modified QuEChERS method coupled with UPLC-MS/MS

Antibiotic residues in honey cause public health problems. To analyze multi-antibiotic residues in honey, a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction method coupled with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed for simultaneous quantification of 70 antibiotic residues in honey. Matrix-matched calibrations indicated the correlation coefficients were higher than 0.998. The recovery was in a range of 70.5%-119.8% with intra-day relative standard deviation (RSD) of ≤ 10.0% and inter-day RSD of ≤ 13.9%. The limits of detection ranged between 0.050 μg/kg and 1.02 μg/kg. Limits of quantification was 0.17 μg/kg to 3.40 μg/kg. The matrix effects were negligible in 71.4% of compounds and moderately in 24.3% of compounds. Methacycline, oxytetracycline, tetracycline and its metabolite 4-tetracycline residues were detected in the tested samples. Validation parameters were acceptable and were in line with the Codex guidelines. This method was effective for detecting multi-antibiotic residues in honey.

A review of green solvent extraction techniques and their use in antibiotic residue analysis

Antibiotic residues are being continuously recognized in the aquatic environment and in food. Though the concentration of antibiotic residues is typically low, adverse effects on the environment and human health have been observed. Hence, an efficient method to determine numerous antibiotic residues should be simple, inexpensive, selective, with high throughput and with low detection limits. Liquid-based extractions have been exceedingly used for clean-up and preconcentration of antibiotics prior to chromatographic analysis. In order to make methods more green and environmentally sustainable, conventional hazardous organic solvents can be replaced with green solvents. This review presents sampling strategies as well as comprehensive and up-to-date methods for chemical analysis of antibiotic residues in different sample matrices. Particularly, solvent-based sample preparation techniques using green solvents are discussed along with applications in antibiotic residue analysis.

Antibiotic residues in wastewaters from sewage treatment plants and pharmaceutical industries: Occurrence, removal and environmental impacts

Sewage treatment plants (STPs) and pharmaceutical manufactories (PMFs) are recognized as important reservoirs for aquatic pollution with antibiotics. Although the occurrence of multiple classes of antibiotics has been mostly reported for STPs and PMFs, knowledge on the effects of wastewater treatment processes on the removal of antibiotics is not well documented. In this study, wastewaters were collected from different treatment points of two STPs and two PMFs in eastern China. Thirty-seven antibiotics within the four classes of fluoroquinolones (FQs), macrolides (MACs), sulfonamides (SAs) and tetracyclines (TCs) were analyzed. Among the investigated antibiotics, 19-33 out of 37 target compounds were detected at least once in the STPs wastewaters ranging from low ng/L to approximately 12.7 μ/L. In the wastewater samples collected from PMFs, up to 34 antibiotics were present with detection frequencies up to 100%, showing generally higher concentrations (up to 19.0 μ/L) than those at the STPs. FQs and SAs were the dominant antibiotic families, which accounted for more than 90% of the total antibiotic concentration in the wastewaters. Moreover, the removal of antibiotics by anaerobic-anoxic-oxic (A²O), membrane bioreactor (MBR) and conventional activated sludge (CAS) systems was evaluated. The MBR system exhibited the best performance, mainly due to the processes of biodegradation and sorption during biological treatments. Notably, several SAs (SMP, SMZ) and FQs (CIN, ENO) antibiotics were consistently detected at concentration levels of μ/L in the effluent samples. The culturable antibiotic-resistance tests and risk assessment indicated that the antibiotic-contaminated effluents would facilitate the development of resistant bacteria and pose high toxicity to non-target organisms in the aquatic environment. Overall, the findings suggested an urgent need for improving the wastewater treatment technologies for simultaneous removal of different classes of antibiotics.

Multi-residue method for the detection of 40 β-lactam-antibiotics in vaccines by LC-MS/MS

Antibiotics are widely used to treat bacterial infections during the process of vaccine production and storage resulting in antibiotic residues that can cause serious harm. A simple and sensitive method for residue analysis of 40 β-lactam antibiotics was developed and validated for vaccines including inactivated enterovirus 71 vaccine (Vero cells), recombinant hepatitis B vaccine (Saccharomyces cerevisiae), and live attenuated varicella vaccine using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI- MS/MS). Samples were prepared with acetonitrile as the protein precipitant. LC separation was performed on a C₁₈ column. These analytes were determined by LC-MS/MS operating multiple-reaction monitoring (MRM) scans in positive mode. The ranges for limits of detection (LOD) and quantification (LOQ) were as follows: 0.02-4 ng/dose (S/N ≥ 3) and 0.04-10 ng/dose in inactivated enterovirus 71 vaccine (Vero cells) and recombinant hepatitis B vaccine (Saccharomyces cerevisiae), 0.04-16 ng/dose and 0.2-20 ng/dose in live attenuated varicella vaccine. The ranges of recoveries of all antibiotics were 84.5%-108.2% in inactivated enterovirus 71 vaccine (Vero cells), 73%-108% in recombinant hepatitis B vaccine (Saccharomyces cerevisiae), and mostly 68.2%-107.8% in live attenuated varicella vaccine. This method simultaneously offers qualitative and quantitative analysis of multi-antibiotics in vaccines, which improves vaccine safety.

Occurrence of antibiotics and antibiotic resistance genes and their correlations in river-type drinking water source, China

The occurrence and distribution of antibiotics and antibiotic resistance genes (ARGs) in natural water has attracted worldwide attention. Antibiotic and ARG pollution in the surface water of drinking water sources might directly/indirectly affect human health. In this study, the distribution of 38 antibiotics, 10 ARGs, 2 integrons, and 16S r DNA in river-type water sources in a large city of China were monitored in winter, which was a period with high level of antibiotic pollution. The results showed that 20 antibiotics were detected with different detection frequencies. The antibiotic pollution in December 2019 was relatively high, with the total concentrations of antibiotics ranging from 281.95 to 472.42 ng/L, followed by that in January 2020 (191.70-337.29 ng/L) and November 2019 (161.25-309.72 ng/L). Sulfacetamide was dominant in November 2019 (23.52-219.00 ng/L) and in January 2020 (113.18-209 ng/L), while norfloxacin in December 2019 (146.72-290.20 ng/L). All the target antibiotics posed low or medium risk for aquatic organisms, and posed low health risk for mankind. Sul1 and erm36 were the predominant ARGs, and intI1 was the predominant integron in drinking water sources. Only tetA showed positive correlations with its corresponding antibiotic (tetracycline). The rest of ARGs showed no correlations with antibiotics or positive / negative correlations with their non-corresponding antibiotics. Overall, the antibiotics and ARG pollution in these water sources was relatively low. These findings provided some reference data for the distribution of antibiotics and ARGs in river-type drinking water sources of large cities in China.

A smart meat packaging to show ciprofloxacin residues based on immunochromatography

The aim of this study was to design a novel smart packaging based on immunochromatography to show ciprofloxacin residues in beef meat. Sensitivity, specificity, accuracy, and precision of this smart packaging were 97%, 100%, 100%, and 97%, respectively. The minimum diagnostic concentration and the minimum diagnostic time were 25 μg/kg and 1 min, respectively. Also, intra- and inter-assays showed all assays were all identical. This means that the smart packaging was a stable and reproducible tool for ciprofloxacin analysis. It is recommended that this type of smart packaging be designed, analyzed, and used to show the residues of common antibiotics in the livestock industry. It is hoped that by obtaining the necessary permits and relevant approvals, this type of packaging can be used for the export and import of various types of meat.

Epidemiological assessment of antibiotic residues in dairy farm milk and farm waste and water in northern India

Antibiotics are frequently used in the dairy sector for prophylactic uses along with therapeutic purposes. Throughout the globe, antibiotic resistance has turned out as one of the greatest public health issue with greater concern in developing countries, such as India. On the matrix wise comparison of the study, slurry samples in all three farming systems show the highest proportion of positive samples. Out of 153 slurry samples, 15.6% samples showed the presence of antibiotic residues. Eighteen milk samples (11.7%) showed the presence of residues following this trend. Only one sample (0.65%) was positive of animal drinking water in the study. None of the targeted residues were found in any sample of human drinking water. The four pond water samples showed the prevalence of residues of oxytetracycline (2 samples) and enrofloxacin (2 samples). Medium size farms (10-30 animals) comprised comparative higher levels than small (< 10) and large farms (> 30). The excretion mass modelling of antibiotics released in the environment indicated 8325.41 kg of oxytetracycline and 12,498.89 kg of enrofloxacin per year. The study helps in providing understanding in the relation between antibiotics usage and dissemination of their residues to the environment which may result in likely ecotoxicological consequences.

Status of antibiotic residues and detection techniques used in Chinese milk: A systematic review based on cross-sectional surveillance data

Antibiotic residues (ARs) in food of animal origin are of worldwide concern, particularly in China, the world's largest producer and consumer of antibiotics. Aiming to provide a reference for the use of antibiotics in dairy cows, for supervision and management departments in the detection of related antibiotics, and for guiding the safe use of antibiotics in food, this systematic review was carried out to determine the prevalence of ARs and antibiotic detection techniques in Chinese milk over the past three decades. The systematic review follows the PRSIMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Both English (Cochrane, Embase, MEDLINE, PubMed, and Web of Science) and Chinese databases (Chinese National Knowledge Infrastructure, China Science and Technology Journal Database, and WanFang Database) were systematically searched, from inception to 31 July 2020. Among the 3131 citations screened, 46 active surveillance cross-sectional studies published between 1988 and 2020 in 26 Chinese provinces were eligible, providing antibiotic levels for a total of 8788 milk samples. Although the AR rates in fresh and sterilized milk fluctuate, they have largely declined in recent years. Among the 18 evaluated antibiotics, sulfamethoxazole, chloramphenicol, and trimethoprim are primary antibiotics with high residual rates. The most frequently used technique to monitor antibiotic levels in milk is 2,3,5-Triphenyltetrazolium chloride (TTC) staining. This review confirmed the importance of food safety monitoring and surveillance systems in preventing antibiotic exceedances in food. Several lessons learned from antibiotic surveillance and supervision in China were revealed. The provision of education to rural farmers should be strengthened to enhance their knowledge on antibiotic use in animal agriculture. Moreover, a standard operational protocol for screening and targeting antibiotics in dairy products should be considered to increase the comparability between cross-sectional active surveillance studies of AR in milk.

Microbiological inhibition-based method for screening and identifying of antibiotic residues in milk, chicken egg and honey

This present study was designed to develop a novel microbiological inhibition-based method for the rapid screening and identification of antibiotic residues in milk, chicken egg and honey. Geobacillus stearothermophilus C953 was used as test bacterium in the detection system of this study. The optimization of nutrients and other supplements were performed to promote the growth of test bacterium and thus shorten the detection time. Furthermore, the synergetic agents were added to improve the sensitivity of test bacterium to more antibiotics. Additionally, confirmatory solutions such as β-lactamase, p-aminobenzoic acid, MgSO₄ and cysteine were added to classify and identify different kinds of antibiotics. We observed that the LOD of this detection system was at or close to maximum residue limits established by EU for β-lactams, aminoglycosides, tetracyclines, sulfonamides, macrolides and quinolones in milk. The LOD of different kinds of antibiotics in chicken egg was less than or similar to the MRL and the LOD of Premi®test (except sulfonamides). For honey, there are no MRL, the LOD was less than or similar to the recommended concentration and the LOD of Premi®test. Noteworthy, the detection system also can identify these six kinds of antibiotics in milk, chicken egg and honey, and there were satisfactory results of specificity experiments and confirmation experiments by LC-MS/MS. Accordingly, the present study provides a reliable preliminary characterization of antibiotic residues in animal foods and improves the detection efficiency for the following chemical confirmation experiments by HPLC, LC-MS/MS, immunological and receptor-based tests.

Distribution, abundance, and risk assessment of selected antibiotics in a shallow freshwater body used for drinking water, China

With rapid improvements in industrialization and urbanization, antibiotics are now extensively used to prevent and treat human and animal diseases and husbandry and aquaculture. Some research has been conducted to assess the environmental distribution and risk level of antibiotics, but their distribution remains largely uncharacterized. Thus, this study investigated the distribution and abundance of 39 antibiotics belonging to five groups, and their associated risks in surface water around Luoma Lake in the north of Jiangsu province, China. Nineteen antibiotics were detected, at a detection frequency (DF) ranging from 2.27% to 100%. The total antibiotics (ΣABs) concentrations ranged from 34.91 to 825.93 ng/L, with a median concentration of 195.45 ng/L. Among these antibiotics, chlortetracycline (DF: 100%; median: 172.02 ng/L) was the dominant antibiotic, accounting for a median percentage of 91.0% of ΣABs concentrations. Spearman rank correlation method found a significant correlation between clindamycin (DF: 72.7%; median: 2.01 ng/L) and lincomycin (DF: 79.5%; median: 4.58 ng/L). The ecological risk quotient (RQ) values for two out of 44 sampling sites were higher than 1, indicating a high risk; 11.4% of the RQ values fell between 0.1 and 1, indicating a medium risk. Moreover, roxithromycin was found to be the dominant contributor to the ecological risk, accounting for a median of 79.7% of ΣABs. However, the total non-carcinogenic (<6.54 × 10^-4) and carcinogenic risks (<1.64 × 10^-7) of ΣABs were negligible at the detected concentrations.

A fluorescent sensing strategy for ultrasensitive detection of oxytetracycline in milk based on aptamer-magnetic bead conjugate, complementary strand of aptamer and PicoGreen

Misuse of antibiotics in animal husbandry and presence of their residues in animal foods is a serious crisis worldwide and thus, monitoring the level of them in food samples is vital for human health. Herein, a fluorescent aptasensor was developed for highly sensitive quantification of oxytetracycline (OTC) in food samples. This method is based on OTC aptamer conjugated to magnetic beads, functioned as recognition element, complementary strand of OTC aptamer, and PicoGreen (PG) as a sensitive double-stranded DNA (dsDNA) fluorescent dye. Formation of OTC aptamer-magnetic bead conjugate provides the opportunity of sample condensation and separation technology. Additionally, the presence of complementary strand leads to significant fluorescence signal alteration of aptasensor in the presence or absence of target and a noteworthy improvement of the aptasensor sensitivity. In the absence of target, complementary strand could bind to aptamer and form dsDNA on the surface of magnetic bead. As a consequence, adding PG to the sample leads to observation of high fluorescence signal from sample. In contrast, once OTC is added to the sample, it binds to OTC aptamer-magnetic bead complex and prevents hybridization of OTC aptamer and its complementary strand. Hence, after addition of PG to the sample, a weak fluorescence intensity is measured. Under optimized conditions, the linear ranges for OTC detection were 0.2-2 nM and 2-800 nM. The detection limit was calculated to be as low as 0.15 nM for the fabricated aptasensor. Besides the great sensitivity, proposed method demonstrated superior specificity towards OTC once it was used against several antibiotics. More significantly, the recovery rates of OTC in milk ranged from 96.46% to 101.5%, implying the great feasibility of designed sensor as well as its potential to be employed for analysis of OTC in real samples.

How much of antibiotics can enter surface water with treated wastewater and how it affects the resistance of waterborne bacteria: A case study of the Białka river sewage treatment plant

This study aimed to gain insight into the presence of antibiotics, occurrence of antimicrobial resistance and prevalence of extended-spectrum β-lactamase (ESBL) genes in Escherichia coli in surface water, based on the example of the Białka river, located in one of the most attractive tourist destinations in Poland. Water samples were collected in three sites: in the Tatra National Park (TNP), by the sewage discharge from the local treatment plant (STP) and c.a. 3 km downstream (DSTP). The analyses included determination of antibiotic content, enumeration of bacterial indicators of poor water quality, isolation and identification of Escherichia coli, which was subjected to antimicrobial susceptibility tests and assessment of ESBL-determining genes. Fourteen antimicrobials out of 24 tested were detected in river waters in varying concentrations. Trimethoprim and ofloxacin were most frequently detected. Most antibiotics were absent in the TNP, the highest numbers and the highest concentrations of antibiotics were observed by the STP discharge to decrease their content downstream. Culture-based tests of microbiological contamination showed similar results. Resistance to ampicillin was most frequent (64.5% strains), followed by cefazolin (50%). 20.6% of strains were ESBL-positive, while ESBL-determining gene, blaTEM was detected in 23.8% of E. coli strains. The largest percentage of antibiotic resistant and MDR E. coli strains was detected nearby the STP, indicating that malfunctioning STP may contribute largely to river water contamination downstream, also having significant environmental and economic impact.

Super-porous semi-interpenetrating polymeric composite prepared in straw for micro solid phase extraction of antibiotics from honey, urine and wastewater

A cryogel-based semi-interpenetrating polymer network (Cryo-SIPN) was prepared in which conductive polymers such as polyaniline (PANI) and polypyrrole (PPy) were formed within the super porous network of acrylic acid cryogel. For completion of cryo-polymerization, all the constituent solutions were severely mixed and placed into the plastic straws and kept at -20°C and then the synthesized cyrogels were cut into the 1-cm length and freeze dried after washing with water. The Cryo-SIPN polymeric composite was applied in micro solid phase extraction (µSPE) of some selected antibiotic residues from various samples. The µSPE method combined with a high performance liquid chromatography-ultraviolet (HPLC-UV) system allowed trace quantification of antibiotic residues in the honey and water samples while the significant variables were optimized using a central composite design (CCD) to find optimum conditions. The method performance was satisfactory with recovery ranges from 70.0 to 109%. The limits of detection (S/N = 3) and quantification (S/N = 10) for all samples were within the 17-50 μg kg^-1 and 47-140 μg kg^-1 range, respectively. The relative standard deviation was less than 10 % for antibiotics in the foodstuff and water samples. The validated Cryo-SIPN-µSPE in conjunction with HPLC-UV, proved to be versatile, efficient and robust while its capability toward the trace determination of drugs residues in real-life samples is demonstrated in this work.

Interface engineering of zeolite imidazolate framework-8 on two-dimensional Al-metal-organic framework nanoplates enhancing performance for simultaneous capture and sensing tetracyclines

The increasing misgivings of environmental pollution derived from antibiotic residues make it imperative to explore a bifunctional platform for synchronous monitoring and removal of antibiotics. Herein, zeolite imidazolate framework-8 (ZIF-8) is anchored on two-dimensional (2D) amino-functionalized Al-metal organic framework (NH₂-MIL-53(Al)) nanoplates to construct a dual metal-organic frameworks smart platform (ZIF-8/NH₂-MIL-53(Al)) for simultaneous capture and fluorescence sensing of tetracyclines (TCs). ZIF-8 nanoparticles anchored on 2D nanoplates having a smaller size and a larger specific surface area boost the adsorption capabilities (561, 533, 526 and 578 mg g^-1 for doxycycline (DOX), tetracycline (TET), oxytetracycline (OTC) and chlortetracycline (CTC), respectively). Notably, the pyridine N of ZIF-8 cooperated with the abundant NH₂ on the surface of NH₂-MIL-53(Al) exhibits high affinity toward TCs, remarkably enhancing the sensitivity by facilitating the photo-induced electron transfer and the inner-filter effect. The LODs (1.2 μg L^-1 for TET, DOX, OTC and 2.2 μg L^-1 for CTC, respectively) are at least 10-fold lower than those of NH₂-MIL-53(Al) and are comparable or superior to those of reported sensors. The dual metal-organic frameworks smart platform presents satisfactory reliabilities and accuracies for detecting TCs in real samples, which anticipates new routes to develop integrated systems for simultaneous capture and detection of organic pollutants.

The search for a microbiological inhibition method for the rapid, broad-spectrum and high-throughput screening of six kinds of antibiotic residues in swine urine

In this study, a microbiological inhibition method for rapidly screening antibiotics in swine urine was established with an easy sample pre-treatment. The microbiological system consisted of an agar medium mixed with nutrients, sensitizers, a test bacterium (Geobacillus stearothermophilus ATCC12980) and pH indicator (bromocresol purple). It was observed that the detection limits of the test kit for twenty-eight common antimicrobial residues in urine, including β-lactams, aminoglycosides, tetracyclines, sulfonamides, macrolides, and lincosamides, were less than or equal to the maximum residue limits of the kidney, as determined by the EU and China. Moreover, the false negative rate and the false positive rate, along with other performance indexes such as interassay coefficients of variation and shelf life of the kit, all met the standard requirements of the ISO13969:2003 guidelines. Additionally, our results were consistent with those using the gold-standard physical chemistry method, which suggest the proposed method is suitable for screening antibiotic residues.

Detection of tetracycline and streptomycin in beef tissues using Charm II, isolation of relevant resistant bacteria and control their resistance by gamma radiation

Background

Misuse of antibiotics in veterinary medicine has the potential to generate residues in animal derived products, which could contributing to the development of an important health risk either through the exposure to antibiotic residues or the transfer of antibiotic resistance among foodborne pathogens as well. Tetracycline (TE) and eptomycin (ST) are commonly used as antibiotics in the Egyptian animal husbandry. The objective of this study, quick detection of TE and ST in fresh local beef tissue samples using radioimmunoassay Charm II technique, isolation and identification of relevant highly resistant bacterial strains. In addition to investigating the effect of gamma radiation on the susceptibility of such resistant strains to TE and ST.

Results

Tetracycline (TE) was detected in all collected samples, while ST was detected in 38.46% (5/13) and 87.5% (7/8) of meat and liver samples, respectively.

Fifty-one bacterial isolates were isolated from the tested samples, among them, the highest resistant isolates to TE or ST were identified as Streptococcus thoraltensis, Proteus mirabilis (2 isolates) and E. coli (3 isolates). Among them, the highest D₁₀-values in phosphate buffer; 0.807 and 0.480; kGy were recorded with S. thoraltensis and E. coli no.3, respectively. Such values increased to record 0.840 and 0.549 kGy, respectively after artificial inoculation into meat, indicating increased resistance to gamma radiation. Gamma radiation at dose 3 kGy increased the susceptibility of S. thoraltensis up to 50% to TE and ST, while the sensitivity of E. coli no.3 reached up 56% to both antibiotics at the same dose.

Conclusions

High prevalence of TE in all fresh collected tissue samples suggests an extensively use of TE as antimicrobial in conventional beef production as compared to ST in the Egyptian cows’ husbandry. Moreover, irradiation of food from animal origin by gamma radiation could potentially provide protection against resistant strains. In spite of limited samples used in this study, our data could raise the concerns of public health professionals about a withdrawal period before animals slaughtering, and address the importance of gamma radiation to minimize the hazards of foodborne resistant bacteria.

Distribution and human health risk assessment of antibiotic residues in large-scale drinking water sources in Chongqing area of the Yangtze River

Antibiotic contamination in drinking water sources has been increasingly prominent in recent years. The water quality in the Chongqing area is not only essential for the local people but also is crucial for the downstream of Yangzi River. To understand the level of antibiotic contamination in the large-scale drinking water sources, this study measured antibiotic residues in nine large-scale drinking water sources (five urban drinking water sources and four township drinking water sources) in Chongqing area of the Yangtze River. Results demonstrated that eight antibiotics of three categories in total were detected, including sulfonamide metformin (SMX), sulfonamide metformin (SMZ), erythromycin (ERM), Roxithromycin (ROM), Tylosin (TYL), Lincomycin (LIN), Chloramphenicol (CAP), and Florfenicol (FF). The mass concentration of antibiotic residues in five urban drinking water sources ranged from 13.9 to 76.6 ng/L, with an average of 46.4 ng/L, and that in four township drinking water sources ranged from 20.6 to 188.1 ng/L, with an average of 88.45 ng/L. The mass concentrations of antibiotic residues in Chongqing area were much lower than those in other cities. Antibiotics posed the maximum risk with a value of 0.005 for 0-3 months of the infant. The risk quotients of antibiotic residues in all water sources were much lower than 1 and thus did not pose a direct threat to human health.

Efficient detection and assessment of human exposure to trace antibiotic residues in drinking water

Human exposure to antibiotic residues in drinking water has not been well evaluated. This study is the first attempt to simultaneously and efficiently identify and quantify 92 antibiotic residues in filtered tap water (multistage filtration at the tap) (n = 36) collected from 10 areas of a large city in southern China, 10 Chinese brands of bottled/barreled water (n = 30) and six foreign brands of bottled water (n = 18) obtained from the Chinese market. The average and median concentrations of all the detected antibiotic compounds was 182 and 92 ng/L in filtered tap water, 180 and 105 ng/L in Chinese brands of bottled/barreled water, and 666 and 146 ng/L in foreign brands of bottled water, respectively. A total of 58 antibiotics were detected in the filtered tap water, and 45 and 36 antibiotics were detected in the Chinese and foreign brands of bottled water, respectively. More types of antibiotics were detected in Chinese brands of bottled water than in the other bottled waters. In addition, Chinese waters had high roxithromycin concentrations, while the foreign brands of bottled water had high concentrations of dicloxacillin. The average and median values of the estimated overall daily intake of all the detected antibiotics were 4.3 and 2.3 ng/kg/day when only filtered tap water was drunk, 4.0 and 2.5 ng/kg/day when Chinese brands of bottled water was drunk, and 16.0 and 4.9 ng/kg/day when foreign brands of bottled water was drunk. Further study is needed to develop a more comprehensive estimation of human exposure to antibiotic residues in the environment and a more in-depth understanding of the potential hazard of ingested antibiotic residues to the human microbiome.

Occurrence of antibiotic residues in Apulian honey: potential risk of environmental pollution by antibiotics

The presence of antibiotic residues in honey is widely documented and is attributed almost exclusively to improper beekeeping practices, due to the frequent use of drugs for the treatment of beehive diseases. Therefore, the aim of our research was to evaluate the presence of antibiotics in honeycomb using the Anti-Microbial Array II (AM II) and IV (AM IV) method and to assess the relationship between environmental context and antibiotic residues in honey. The results show the presence of antibiotic residues in 26/50 honey from brood nests samples, confirming the impact of environmental contamination on the health quality of this food product. In addition, subsequent analyses conducted on positive samples reveal the instability over time of antimicrobial molecules in honey. These results highlight the need for further studies in order to understand all likely sources of contamination and to implement a comprehensive safety management plan for honey.

Association between antibiotic residues, antibiotic resistant bacteria and antibiotic resistance genes in anthropogenic wastewater - An evaluation of clinical influences

The high use of antibiotics in human and veterinary medicine has led to a wide spread of antibiotics and antimicrobial resistance into the environment. In recent years, various studies have shown that antibiotic residues, resistant bacteria and resistance genes, occur in aquatic environments and that clinical wastewater seems to be a hot spot for the environmental spread of antibiotic resistance. Here a representative statistical analysis of various sampling points is presented, containing different proportions of clinically influenced wastewater. The statistical analysis contains the calculation of the odds ratios for any combination of antibiotics with resistant bacteria or resistance genes, respectively. The results were screened for an increased probability of detecting resistant bacteria, or resistance genes, with the simultaneous presence of antibiotic residues. Positive associated sets were then compared, with regards to the detected median concentration, at the investigated sampling points. All results show that the sampling points with the highest proportion of clinical wastewater always form a distinct cluster concerning resistance. The results shown in this study lead to the assumption that ciprofloxacin is a good indicator of the presence of multidrug resistant P. aeruginosa and extended spectrum β-lactamase (ESBL)-producing Klebsiella spec., Enterobacter spec. and Citrobacter spec., as it positively relates with both parameters. Furthermore, a precise relationship between carbapenemase genes and meropenem, regarding the respective sampling sites, could be obtained. These results highlight the role of clinical wastewater for the dissemination and development of multidrug resistance.

Comparison of international legislation and standards on veterinary drug residues in food of animal origin

Current legislation governing monitoring of drug residues in foodstuff of animal origin is being revised at the European level. This study provides a qualitative comparison of the legislation, public and private standards in the European Union, the United States of America (USA) and the Eurasian Customs Union/Russia. We made a quantitative comparison of Maximum Residue Levels (MRLs) applied in each region for pork kidneys for tetracycline (with a focus on doxycycline), penicillin and chloramphenicol. The Customs Union generally applied lower levels than the other regions, with MRLs for tetracyclines in pig kidneys being 1200 times lower than those applied in the USA. Growing consumer interest and concern about chemicals in their food could be leveraged to support and enhance the implementation of new initiatives to improve veterinary public health. Farmers and veterinarians could help reduce findings of drug residues in meat through the judicious use of preventive actions when using veterinary medicine.