Screening Of Antibiotic Residues Research Articles

Rapid testing of antibiotic residues to increase food safety awareness of animal origin.

Antibiotics are used to improve growth, reduce disease, and decrease mortality in animals grown for food. The government regulates and prohibits the use of antibiotics, in particular, the use of antibiotic growth promoter (AGP) in livestock; however, it is not yet known whether the use of antibiotics is in accordance with regulations so that there are no antibiotic residues in food of animal origin. To ensure food safety of animal origin and to raise awareness of food safety, it is necessary to detect antibiotic residues in fish, eggs, and chicken meat from Yogyakarta Special Province through monitoring and monitoring. To ensure food safety and regulatory compliance in food samples, antibiotic residue screening techniques are essential. A number of methods, such as time-consuming and costly chromatographic and spectroscopic methods, have been developed for the detection of antibiotic residues in food samples; however, not all laboratories have these facilities. Therefore, a rapid diagnosis of food of animal origin is required. The purpose of this study was to rapidly test antibiotic residues by using Premi®test kits (R-Biopharm AG, Germany) to increase awareness of food safety of animal origin. We tested 345 animal-based food samples from traditional markets, supermarkets, and central markets in five districts of Yogyakarta Special Province for antibiotic residues using rapid test kits and observation questionnaires to identify risk factors. The presence of antibiotic residues in food-animal origin samples from the Yogyakarta region had an antibiotic residue level of 9.28% (32/345), consisting of fish samples 11.3% (18/97), eggs 15.65% (1/114), and chicken meat samples 0.87% (13/102). The highest percentage of samples positive for residual antibiotics was 21.9% (7/32) from supermarket meat samples. The highest amounts of antibiotic residues were found in fish samples collected from Sleman Regency, up to 25% (8/32), whereas in supermarket fish samples, there were as high as 18.8% (6/32). Antibiotic residues in animal-based food can be attributed to various factors, including product source, transportation conditions, and environmental conditions. The widespread distribution of antibiotic residues in fish comes from environmental conditions during maintenance, distribution, and retailing. Monitoring antibiotic residue prevalence in food-animal origins, particularly chicken meat, eggs, and fish, is crucial for improving animal food quality and safety.

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.

Detection of Antibiotic Residues in Broiler Meat by Thin Layer Chromatography

Antibiotic usage has played a significant role in the growth of poultry industry all across the globe. But because of indiscriminate use of antibiotics, several incidences related to occurrence of antibiotic residues in broiler meat have been reported. In the context of Nepal, only limited studies have been attempted to assess the presence of antibiotic residues in poultry meat and thus this study aims to determine the same in Dharan. A questionnaire survey was conducted among poultry farmers and veterinary shops in Dharan where 44% of respondents had training on poultry farming but only 4 % had knowledge on antimicrobial resistance in microorganism. The survey report showed maximum usage of doxycycline and tetracycline in poultry farms. Four types of broiler meat, namely, liver, breast muscle, kidney and gizzard were collected and screening of antibiotic residues (ciprofloxacin, doxycycline, enrofloxacin, gentamycin and tetracycline) in them was performed by thin layer chromatography. On thin layer chromatography, 9%, 17%, 8%, 3% and 21% of samples were detected with ciprofloxacin, doxycycline, enrofloxacin, gentamycin and tetracycline residues respectively. Highest occurrence of ciprofloxacin, doxycycline, enrofloxacin and tetracycline residues were found in kidney (16%), gizzard (32%), liver (12%) and kidney (36%) samples respectively.

Microbial Screening of Antibiotic Residues in Soil and Water of Cultured Fish Farms in Tamil Nadu

Background: Aquaculture is one of the main protein sources in the world. Due to the intensification in aquaculture, the occurrence and the spread of disease is more. To control and treat the disease in aquaculture, farmers started using antibiotics in improper manner. This leads to the deposition of antibiotic residues in water and soil, which later transformed to fish that makes them resistant to that particular antibiotic. It was later transformed to other animals and humans, which makes them resistant to that antibiotic. Henceforth there is a need to screen the presence of antimicrobial residues in soil and water. Methods: In this study, microbiological methods were used for screening antimicrobial residues. For microbial screening, Bacillus subtilis and Escherichia coli were used as a marker microorganism. Totally 75 samples of soil and 75 samples of water were screened for antimicrobial residues. Result: The results revealed that 8%, 4% and 13.33% of pond soil samples and 10.66%, 6.66% and 21.33% of pond water samples were contaminated with oxytetracycline hydrochloride, florfenicol, sulphadimethoxine and ormetoprim residues. This review clarifies that microbial screening has a unique advantage of economical and a simple method that can be used as a preliminary method for screening antibiotic.

Hollow NiCo@C Nanozyme-Embedded Paper-Based Colorimetric Aptasensor for Highly Sensitive Antibiotic Detection on a Smartphone Platform.

Antibiotic residues in the environment and in foods pose a serious threat to ecosystems and human health. Developing sensitive and on-site detection methods is therefore in high demand. In this work, a portable paper-based colorimetric sensor with a smartphone platform with an ultrahigh sensitivity has been designed for on-site and quantitative analysis of antibiotic residues based on aptamer-regulated nanozyme activity. The developed excellent peroxidase-like nanozymes, carbon-protected NiCo bimetal oxides with a unique hollow nanocage structure (NiCo@C HCs), could effectively catalyze the oxidation of chromogenic substrates by H2O2. Once bound to a specific aptamer, the enzyme-mimicking activity of NiCo@C HCs is obviously inhibited as a result of the masking of active sites but could be restored via the target-aptamer recognition. Herein, the aptamer-modified NiCo@C HCs are embedded on paper pieces to construct paper-based biochips for visual detection. Meanwhile, a smartphone platform is integrated for the signal readout. Using enrofloxacin (ENR) as an analyte model, the proposed paper-based analysis platform shows a reliable and sensitive detection of ENR with an ultralow detection limit of 0.029 ng/mL. The platform also works well in various real samples. This analysis method is facile in design, showing a great application potential for on-site and mass screening of antibiotic residues in the environment and in foods.

Chemiluminescence microarray immunoassay for multiple aminoglycoside antibiotics based on carbon nanotube-assisted signal amplification.

The simultaneous determination of multiple analytes has been an urgent demand in screening of antibiotic residues in food products of animal origin due to its higher analysis efficiency. Five aminoglycoside antibiotics (AGAs) have been monitored in milk, including gentamicin (GEN), kanamycin (KAN), neomycin (NEO), and streptomycin/dihydrostreptomycin (STR/diSTR). A chemiluminescence microarray immunoassay (CLMIA) based on nitrocellulose membrane had been developed for the detection of multiple AGAs, which the LODs for STR, KAN, NEO, and GEN were 4.74ng/mL, 4.97ng/mL, 2.99ng/mL, and 4.42ng/mL respectively. To improve the sensitivity of immunoassay, single-well carbon tubes (SWCNTs) were utilized as solid support for loading horseradish peroxidase-labelled goat anti-mouse antibody to obtain the multi-enzyme particles. After the optimization of usage of multi-enzyme particles and antibodies, the enhanced CLMIA was established and evaluated. The LODs were 1.25ng/mL for STR, 0.64ng/mL for KAN, 0.38ng/mL for GEN, and 0.39ng/mL for NEO, which was improved by threefold, sevenfold, 11-fold, and sevenfold compared with the conventional CLMIA developed. These methods presented higher specificity and repeatability. Finally, the enhanced CLMIA based on CNT-assisted multi-enzyme particles was utilized to analyze twenty-five milk samples from local market and dairy farm, which all the results were below the LOD. The enhanced CLMIA showed the great application potential for the detection of multiple targets simultaneously and provided efficient tool for the screening of pollutants in food.

Rapid Screening of Antibiotic Residues in Milk Powder Using Direct Analysis in Real Time High Resolution Mass Spectrometry

Rapid Screening of Antibiotic Residues in Milk Powder Using Direct Analysis in Real Time High Resolution Mass Spectrometry

Screening of antibiotic residues in raw milk of cows and buffalos by diffusion assays.

Although antibiotics are valuable drugs for treatment of certain infections, their presence in foodstuff derived from animals is a potential public health hazard. They pose a serious threat as they are implicated in direct toxicity; allergic reactions; disturbance of the normal gut microbiota, carcinogenesis, and emergence of antibioticresistant bacteria. This study investigated the occurrence of antibiotic residues in raw milk samples derived from cows and buffaloes. Samples were collected randomly from different retail outlets in Erbil city (Iraq) from January 1st to June 30th, 2019. The residues were detected by two diffusion assays against Bacillus subtilis bacteria on agar plates. The total occurrence of residues ranged from 11.9% to 13.4% of screened milk samples. No significant differences were found between milk type or location of animal rearing (urban or suburban). Regarding the seasonal variations, spring was found to be associated with gradual decrease in antibiotic residues levels in milk. Such occurrence rate of residues is alarming and require authorities to observe the quality of raw milk introduced to markets for consumption. Further evaluation of antibiotic stability period in raw milk is also necessary.

Protecting Consumer Health by Developing an Electrochemical Immunosensor for the Detection of Banned Antibiotic Residues in Honey

IntroductionChemical (eg pesticides, veterinary drugs, etc.) and bacteriological contaminants (eg. foodborne pathogens) could contaminate animal and plant derived food products for human consumption. Some antibiotic residues (eg. chloramphenicol, nitrofuran metabolites, dyes) are banned in foodstuffs of animal origin (eg. milk, meat, eggs, etc.) in European Union because of toxicological risks for the consumer. The European Regulation has set Minimum Required Performance Limits (MRPL) [1] or Reference Point for Action (RPA) for banned substances [2]. Food containing residues of substances at or above the MRPL or RPA are declared non-compliant and consignments are rejected from the consumer's market.Screening methods are the first stage of food control and so are essential for food safety monitoring. Conventional screening methods are microbiological methods (eg. plate tests, tube tests), immunological methods (eg. ELISA, radioimmunoassays) or physico-chemical methods (Thin Layer Chromatography, High Performance Liquid Chromatography (HPLC), liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)). These methods sometimes lack of sensitivity or specificity; they also could be time and money consuming. There is thus a need to develop novel screening methods for antibiotic residues detection, preferably with the potential for the field-testing (eg. farm control, self-control). Electrochemical biosensors make it possible to develop a promising and economically interesting approach.Electrochemical immunosensorAn innovative electrochemical method based on disposable Screen Printed Carbon Electrodes (SPCE), coupled to magnetic beads (MB), allowing the simultaneous detection of 3 families of antibiotics in milk, was published by a Spanish academic team [3]. This technique presents major advantages: low cost (eg. disposable electrodes, potentiostat), promising detection limits, portability, and possible automatisation. Our laboratory has evaluated the transferability of the method. An electrochemical immunosensor has been developed for the detection of chloramphenicol residues in honey as a proof of concept. Honey composition and colour varies considerably depending on the botanical origin. Moreover some honey ingredients can interfere with the electrochemical detection, especially substances with antioxidant activities (eg. polyphenols). Therefore a lot of work had to be done to improve sample extraction to reduce matrix effects.The objective is to develop an electrochemical bead-based immunosensor for the multiplex detection of banned antibiotics (eg. chloramphenicol, nitrofuran metabolites, dyes) in bovine milk.MethodAntibodies (Abs) against antibiotics are grafted on the surface of magnetic beads (MBs). Milk samples and antibiotic conjugated with Horseradish peroxidase (HRP) are mixed with MBs-Abs. A competition occurs between the HRP conjugates and the antibiotic residues if present in the sample, for the binding to the antibody. The MBs are washed to remove free antibiotics and conjugates. Then, a Screen Printed Carbon Electrode (SPCE) with MBs on its surface (maintained by a magnet) is soaked into a buffer solution containing hydroquinone; when adding hydrogen peroxide (H2O2) to the solution, an electrochemical signal is produced, due to the enzymatic activity of HRP and measured. The electrochemical signal is inversely proportional to the antibiotic concentration in the sample.Results and ConclusionsScreening methods for the detection of veterinary drugs in food products have to be validated according to the European regulation [1] and to the European guideline for the validation of screening methods [4]. After the development and the optimization of the analytical parameters (eg. sample preparation, HRP concentration, incubation time, applied potential, etc), the methods developed for single compounds will be evaluated and validated according to the European regulations. Then the single compound methods will be merged into one multiplex method if possible. The results will be presented to the conference, discussing the advantages and drawbacks of electrochemical biosensors for the screening of antibiotic residues in food products.

Detección de residuos de antibióticos y micotoxinas en leche vacuna fluida pasteurizada comercializada en Paraguay

Introducción: La frecuencia de residuos de antibióticos y de micotoxinas presentes en la leche por encima de los límites máximos establecidos, ha aumentado en los últimos años, representando un riesgo para la salud pública a nivel mundial. En Paraguay, la investigación existente es deficiente al respecto, por lo que es prioritario realizar un diagnóstico de situación.

Longitudinal screening of antibiotic residues, antibiotic resistance genes and zoonotic bacteria in soils fertilized with pig manure.

Fertilization with animal manure is one of the main routes responsible for the introduction of antibiotic residues, antibiotic resistance genes, and zoonotic bacteria into the environment. The aim of this study was to assess the effect of the use of pig (swine) manure as a fertilizer on the presence and fate of six antibiotic residues, nine antibiotic resistance genes, and bacteria (zoonotic bacteria Salmonella spp. and Campylobacter spp. and E. coli as indicator for Gram-negative bacterial species of the microbiota of livestock) on five fields. To the best of our knowledge, the present study is the first to assess a multitude of antibiotic residues and resistance to several classes of antibiotics in pig manure and in fertilized soil over time in a region with an intensive pig industry (Flanders, Belgium). The fields were sampled at five consecutive time points, starting before fertilization up to harvest. Low concentrations of antibiotic residues could be observed in the soils until harvest. The antibiotic resistance genes studied were already present at background levels in the soil environment prior to fertilization, but after fertilization with pig manure, an increase in relative abundance was observed for most of them, followed by a decline back to background levels by harvest-time on all of the fields studied. No apparent differences regarding the presence of antibiotic resistance genes in soils were observed between those fertilized with manure that either contained antibiotic residues or not. With regard to dissemination of resistance, the results presented in this study confirm that fertilization with animal manure directly adds resistance genes to the soil. In addition, it shows that this direct mechanism may be more important than possible selective pressure in soil-dwelling bacteria exerted by antibiotic residues present in the manure. These results also indicate that zoonotic bacteria detected in the manure could be detected in the soil environment directly after fertilization, but not after 1 month. In conclusion, although some antibiotic residues may be present in both manure and soil at concentrations to exert selective pressure, it seems that antibiotic resistance is mostly introduced directly to soil through fertilization with animal manure.

Effective screening of antibiotic and coccidiostat residues in food of animal origin by reliable broad-spectrum residue screening tests

Foods of animal origin are controlled for antibiotic and coccidiostat residues. The rapid residue detection is possible using reliable broad-spectrum screening tests. This study’s objective using four microbial inhibition tests for the detection and identification of antibiotic and coccidiostat residues in different foods of animal origin: Premi®Test, EXP Ampulle test, Milchtest and Screening Test for Antibiotic Residues (STAR). Four hundred and thirty (430) food samples (165 animal tissues, 152 raw cow’s milk and 113 eggs) were randomly collected and screened. Using the Premi®Test, 18 samples were positive and 6 samples dubious. Using the EXP Ampulle test, 31 samples were positive and 2 samples dubious. Using the Milchtest, 15 samples were positive and 12 samples dubious. Using the STAR, 65 samples were positive with 62 samples positive on plates specific for beta-lactams and sulphonamides, 4 samples on plates specific for aminoglycosides, 8 samples on plates specific for macrolides and beta-lactams; and 7 samples on the plates specific for tetracyclines. Retesting using penicillinase and para-aminobenzoic acid (PABA) to confirm the presence of beta-lactams or sulphonamides all potentially positive tube test samples revealed 21 samples positive for beta-lactams and 27 samples positive for sulphonamides. Further testing of sulphonamide positive chicken samples revealed the positivity for coccidiostat salinomycin which was confirmed by testing with PABA, which counteracting salinomycin inhibition. Three hundred and sixty six (366) animal food samples were negative for antibiotic and coccidiostat residues. Microbial inhibition tests are preferred for initial antibiotic screening and have also proven useful for coccidiostat screening and post-screening. HIGHLIGHTS Foodstuffs of animal origin are subject to controls on antibiotic and coccidiostat residues. Microbial inhibition tests are still the preferred choice for the initial screening of antibiotic residues in food matrices and could become a useful tool for the screening of coccidiostat residues also. More specific post-screening analysis with PABA proved unexpectedly to be a reliable tool in the preliminary detection of coccidiostat residues in poultry meat and eggs.

Protecting Consumer Health By Developing a Multiplex Amperometric Immunosensor for the Detection of Banned Antibiotic Residues in Milk

Introduction Chemical (eg pesticides, veterinary drugs, etc.) and bacteriological contaminants (eg. foodborne pathogens) could contaminate animal and plant derived food products for human consumption. Some antibiotic residues (eg. chloramphenicol, nitrofuran metabolites, dyes) are banned in foodstuffs of animal origin (eg. milk, meat, eggs, etc.) in European Union because of toxicological risks for the consumer. The European Regulation has set Minimum Required Performance Limits (MRPL) [1] or Reference Point for Action (RPA) for banned substances [2]. Food containing residues of substances at or above the MRPL or RPA are declared non-compliant and consignments are rejected from the consumer’s market.Screening methods are the first stage of food control and so are essential for food safety monitoring. Conventional screening methods are microbiological methods (eg. plate tests, tube tests), immunological methods (eg. ELISA, radioimmunoassays) or physico-chemical methods (Thin Layer Chromatography, High Performance Liquid Chromatography (HPLC), liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)). These methods sometimes lack of sensitivity or specificity; they also could be time and money consuming. There is thus a need to develop novel screening methods for antibiotic residues detection, preferably with the potential for the field-testing (eg. farm control, self-control). Electrochemical biosensors make it possible to develop a promising and economically interesting approach. Electrochemical immunosensor An innovative electrochemical method based on disposable Screen Printed Carbon Electrodes (SPCE), coupled to magnetic beads (MB), allowing the simultaneous detection of 3 families of antibiotics in milk, was published by a Spanish academic team [3]. This technique presents major advantages: low cost (eg. disposable electrodes, potentiostat), promising detection limits, portability, and possible automatisation. Our laboratory has evaluated the transferability of the method. An electrochemical immunosensor has been developed for the detection of chloramphenicol residues in milk as a proof of concept. The matrix effect (milk samples) was high and so sample preparation has to be improved to reduce matrix effects.The objective is to develop an amperometric bead-based immunosensor for the multiplex detection of banned antibiotics (eg. chloramphenicol, nitrofuran metabolites, dyes) in bovine milk. Method Antibodies (Abs) against antibiotics are grafted on the surface of magnetic beads (MBs). Milk samples and antibiotic conjugated with Horseradish peroxidase (HRP) are mixed with MBs-Abs. A competition occurs between the HRP conjugates and the antibiotic residues if present in the sample, for the binding to the antibody. The MBs are washed to remove free antibiotics and conjugates. Then, a Screen Printed Carbon Electrode (SPCE) with MBs on its surface (maintained by a magnet) is soaked into a buffer solution containing hydroquinone; when adding hydrogene peroxide (H2O2) to the solution, an amperometric signal is produced, due to the enzymatic activity of HRP and measured. The amperometric signal is inversely proportional to the antibiotic concentration in the sample. Results and Conclusions Screening methods for the detection of veterinary drugs in food products have to be validated according to the European regulation [1] and to the European guideline for the validation of screening methods [4]. After the development and the optimization of the analytical parameters (eg. sample preparation, HRP concentration, incubation time, applied potential, etc), the methods developed for single compounds will be evaluated and validated according to the European regulations. Then the single compound methods will be merged into one multiplex method if possible. The results will be presented to the conference, discussing the advantage sand drawbacks of amperometric biosensors for the screening of antibiotic residues in food products.

Multi-dimensional fluorescence spectroscopy coupled with chemometrics in rapid antibiotic detection and discrimination

Antibiotic residues in animal-derived foods pose risk to human health including chemical poisoning and antimicrobial resistance, and therefore, constant monitoring throughout the food supply chain is important. In the present study multi-dimensional fluorescence spectroscopy (3D and 2D) coupled with chemometric tools were tested for potential application to detect, discriminate and quantify penicillin G (PG), sulfadiazine (SF) and tetracycline (TC) in milk by direct measurement. Qualitative and quantitative calibration models were developed for prediction of antibiotic residues. Results demonstrated optimal discrimination of milk samples on the basis of antibiotic type and concentration with close to 100% of accuracy. Negative correlation between antibiotic concentration and fluorescence peak height was displayed (r ≥ 0.963 and p ≤ 0.002). A great potential for quantitative antibiotic determination was established with R2 > 0.9 and low standard errors of estimation indicating acceptable precision for the developed technique. Fluorescence spectroscopy demonstrated high specificity and sensitivity with detection limit below the maximum residue limit of PG, SF and TC in milk. Therefore, fluorescence spectroscopy can be used as an alternative method for rapid screening of antibiotic residues in milk at collection centers and processing plants to ensure product quality and safety.

Survey on the presence of antibiotic residues in raw milk samples from six sites of the dairy pool of Niamey, Niger.

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.

Facile synthesis of SiO2@MnO2 nanocomposites and their applications on platforms for sensitively sensing antibiotics and glutathione

In 2-(N-morpholino)ethanesulfonic acid buffer (0.1 M, pH 6.0), manganese dioxide-modified silicon dioxide (SiO2@MnO2) nanocomposites were facilely synthesized under ultrasonic conditions. Given their good biocompatibility and evident brown color, SiO2@MnO2 nanocomposites were used as labels in immunochromatography sensor for high-throughput screening of antibiotic residues in milk within 10 min. Meanwhile, excessive amounts of antibiotic residues might cause certain diseases and inhibit the activities of glutathione reductase in human body through the food chain, altering glutathione (GSH) levels in the human serum. GSH can reduce MnO2 to Mn(II). This phenomenon can effectively quench the fluorescence of Au nanoclusters. Thus, a fluorescent platform based on SiO2@MnO2 nanocomposites and Au nanoclusters has been designed for sensitive detection of GSH in the human serum with a limit of detection of 1.23 nM. After the parameters were optimized, the developed detection platforms based on SiO2@MnO2 nanocomposites have been used to detect antibiotics and GSH in real samples (milk and human serum) with satisfactory results. Results demonstrated that the proposed SiO2@MnO2 nanocomposites hold great potential for applications in food safety and clinical diagnosis simultaneously.

Five-assay microbiological system for the screening of antibiotic residues

A novel microbiological system in microtiter plates consisting of five bioassays is presented for the detection and classification of antibiotic residues in milk. The bioassays were optimized for the detection of beta-lactams (Bioassay B: Geobacillus stearothermophilus), macrolides (Bioassay M: Bacillus megaterium with fusidic acid), tetracyclines (Bioassay T: B. megaterium with chloramphenicol), quinolones (Bioassay Q: Bacillus licheniformis) and sulfamides (Bioassay QS: B. licheniformis with trimethoprim) at levels near the maximum residue limits (MRL). The response of each bioassay was interpreted visually (positive or negative) after 4–5.5h of incubation. The system detects and classifies beta-lactams (5μg/l of amoxicillin, 4μg/l of ampicillin, 36μg/l of cloxacillin, 22μg/l of amoxicillin, 3μg/l of penicillin, 114μg/l of cephalexin, 89μg/l of cefoperazone and 116μg/l of ceftiofur), tetracyclines (98μg/l of chlortetracycline, 92μg/l of oxytetracycline and 88μg/l of tetracycline), macrolides (33μg/l of erythromycin, 44μg/l of tilmicosin and 50μg/l of tylosin), sulfonamides (76μg/l of sulfadiazine, 85μg/l of sulfadimethoxine, 77μg/l of sulfamethoxazole and 87μg/l of sulfathiazole) and quinolones (94μg/l of ciprofloxacin, 98μg/l of enrofloxacin and 79μg/l marbofloxacin). In addition, the specificity values were high for B, T, Q (99.4%), M (98.8%) and QS (98.1%) bioassays. The control of antibiotics through this system can contribute to improving the quality and safety of dairy products.

Time dependent screening of antibiotic residues in milk of antibiotics treated cows.

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.

Simultaneous screening of antibiotic residues in honey by biochip multi-array technology

The existence of antibiotic residues in food causes serious health problems in humans. This study aims to determine antibiotic residues in honey intended for consumption. Evidence Investigator™ Biochip Array technology enables simultaneous quantitative detection of multiple analytes on a single sample. The Anti Microbial Array IV test kit is used in simultaneously detecting the quantity of 12 different groups of antimicrobials in honey samples. A competitive chemiluminescent immunoassay was employed for the detection of antimicrobials. The light signal produced from each test region on the biochip was detected using digital imaging technology. In this study, a total of 45 honey samples including 5 brands of honey and 40 local honey were analyzed. The honey samples were simultaneously screened for 12 different types of antibiotic residues by using the Evidence Investigator™ Anti Microbial Array IV test kit. In the honey samples examined, residues of erythromycin, streptomycin, amikacin, lincosamides, tylosin B and neomycin were detected. 91% of samples involved erythromycin residues whereas 15% of the local samples included streptomycin residues above the recommended concentration.

Multiplexed electrochemical aptasensor for antibiotics detection using metallic-encoded apoferritin probes and double stirring bars-assisted target recycling for signal amplification

Simultaneous and sensitive detection of various antibiotic residues in one sample is essential to evaluation of food safety status. Herein, a multiplexed electrochemical aptasensor for multiplex antibiotics detection, with kanamycin (KANA) and ampicillin (AMP) as representative analytes, was designed by using metal ions encoded apoferrtin probes and double stirring bars-assisted target recycling for signal amplification. The encoded probes were prepared by apoferritin loading Cd2+ and Pb2+ ions and labeling with duplex DNAs (aptamers corresponding to KANA and AMP hybrid with its complementary DNA sequence), respectively. In the presence of KANA and AMP, the targets can recurrently react with the probes on the bars, and then replace a lot of Apo-Mencoded signal tags into supernatant. The peak currents of Cd2+and Pb2+from the tags corresponding with the concentrations of KANA and AMP were detected by square wave voltammetry in one run. As a result, KANA and AMP can be detected simultaneously within the range from 0.05 pM to 50 nM. And the detection limits were 18 fM KANA and 15 fM AMP (S/N = 3). The assay was testified to detect KANA and AMP residues with consistent results of ELISA in samples, e.g. milks and fishes. The assay was highly-sensitive, selective, cost-effective and easy-to-operate due to Apo-M encoded probes with high loading capacity of signal source substances. Moreover, double stirring bar-assisted target recycling, which was enzyme-free and could overcome matrix interference, was fabricated for signal amplification. Thus, the assay showed potential advantages for sensitively screening of antibiotic residues in foods.