Veterinary drug residues in meat: Concerns and rapid methods for detection

Identifying critical factors influencing the disposal of dead pigs by farmers in China

Disposal of dead pigs by pig farmers may have a direct impact on pork safety, public health, and the ecological environment in China. Drawing on the existing literature, this study analyzed and summarized the main factors that could affect the disposal of dead pigs by pig farmers by conducting a survey of 654 pig farmers in Funing County, Jiangsu Province, China. The purpose of this analysis was to investigate the disposal of dead pigs in China and provide useful regulatory strategies for the government. The interrelationships among dimensions and factors that affect the disposal of dead pigs by farmers were analyzed, and critical factors were identified by a hybrid multi-criteria decision-making method, which is a combination of decision-making trial and evaluation laboratory (DEMATEL) and analytic network process (ANP). Our results demonstrated that production characteristics were the most important dimensions and that costs and profits, scale of farming, pattern of farming, knowledge of relevant laws and regulations, and knowledge of pig disease and prevention were the five most critical factors affecting the disposal of dead pigs by farmers in China at this stage. The significance of this study lies in further discussing some management policies for the Chinese government regarding strengthen regulation of disposing dead pigs.

Chromatographic detection of nitrofurans in foods of animal origin

Nitrofurans are antibacterials banned in livestock by different countries due to its relationship with the production of carcinogenic metabolites. Several studies have been conducted to find the best methodology to identify these residues. Te objectives of this review work were to show the risk of nitrofuran metabolites (furazolidone; nitrofurazone; nitrofurantoin, furaltadone and nifursol); to explain the application of liquid chromatography and mass spectrometry to determine the presence of these residues in foods of animal origin; and, finally, to report some methodologies that were recently used in different foods of animal origin.

Multi-residue and multi-class method for the determination of antibiotics in bovine muscle by ultra-high-performance liquid chromatography tandem mass spectrometry

A multi-residue quantitative screening method covering 41 antibiotics from 7 different families, by ultra-high-performance-liquid-chromatography tandem mass spectrometry (UHPLC-MS/MS), is described. Sulfonamides, trimethoprim, tetracyclines, macrolides, quinolones, penicillins and chloramphenicol are simultaneously detected after a simple sample preparation of bovine muscle optimized to achieve the best recovery for all compounds. A simple sample treatment was developed consisting in an extraction with a mixture of acetonitrile and ethylenediaminetetraacetic acid (EDTA), followed by a defatting step with n-hexane. The methodology was validated, in accordance with Decision 2002/657/EC by evaluating the required parameters: decision limit (CCα), detection capability (CCβ), specificity, repeatability and reproducibility. Precision in terms of relative standard deviation was under 20% for all compounds and the recoveries between 91% and 119%. CCα and CCβ were determined according the maximum residue limit (MRL) or the minimum required performance limit (MRPL), when required.

Sports doping: emerging designer and therapeutic β2-agonists

Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future.

Simultaneous detection of sulfamethazine and sulfaquinoxaline using a dual-label time-resolved fluorescence immunoassay

A dual-label time-resolved fluoroimmunoassay (TRFIA) was introduced for the simultaneous quantification of sulfamethazine (SM2) and sulfaquinoxaline (SQX). Lanthanide (Eu(3+) and Sm(3+))-labelled antibodies were used because lanthanides have higher stabilities and narrower emission spectra than most fluorescent dyes. The sensitivity of the TRFIA for SM2 was 0.02 ng ml(-1), and the average recoveries and the intra- and inter-assay CVs were 77.2-107.6%, 5.4-10.5%, and 6.0-11.2%, respectively. The sensitivity of the TRFIA for SQX was 0.04 ng ml(-1); and the average recoveries and the intra- and inter-assay CVs were 74.1-102.8%, 4.6-10.9%, and 8.7-11.2%, respectively. The method was used to analyse chicken tissue and egg samples, and the results agreed well with the results of HPLC and enzyme-linked immunosorbent assay (ELISA) analyses, with correlation coefficients (R(2)) of 0.9415-0.9724. The TRFIA developed is a simple, fast and sensitive method for the high-throughput simultaneous screening of SM2 and SQX in edible animal tissues.

Trends in monitoring residues of pharmacologically active group B substances in products of animal origin in Lithuania from 1999 to 2008

Monitoring data of group B pharmacologically active substances in the Republic of Lithuania during the period 1999-2008 are presented. Peer review is based on data taken from residue-monitoring plans of the years 1999-2008 and the National Food and Veterinary Risk Assessment Institute reports on analyses performed in various foods. The data were analysed with the SPSS statistical package. Analysis of group B pharmacologically active substances residues monitoring results from the years 1999-2008 revealed that 25,030 samples were tested to detect 421 (1.68%) non-compliant samples in three groups of substances: antibacterials, anthelmintics and non-steroidal anti-inflammatory drugs. Most residues (88.3%) were found in milk, and were far less in beef, pork, sheep and goat meat.

Direct quantification and distribution of tetracycline-resistant genes in meat samples by real-time polymerase chain reaction

The evolution of antimicrobial-resistant bacteria has become a threat to food safety and methods to control them are necessary. Counts of tetracycline-resistant (TR) bacteria by microbiological methods were compared with those obtained by quantitative PCR (qPCR) in 80 meat samples. TR Enterobacteriaceae counts were similar between the count plate method and qPCR (P= 0.24), whereas TR aerobic mesophilic bacteria counts were significantly higher by the microbiological method (P < 0.001). The distribution of tetA and tetB genes was investigated in different types of meat. tetA was detected in chicken meat (40%), turkey meat (100%), pork (20%), and beef (40%) samples, whereas tetB was detected in chicken meat (45%), turkey meat (70%), pork (30%), and beef (35%) samples. The presence of tetracycline residues was also investigated by a receptor assay. This study offers an alternative and rapid method for monitoring the presence of TR bacteria in meat and furthers the understanding of the distribution of tetA and tetB genes.

Optical biosensors for food quality and safety assurance-a review

Food quality and safety is a scientific discipline describing handling, preparation and storage of food in ways that prevent food borne illness. Food serves as a growth medium for microorganisms that can be pathogenic or cause food spoilage. Therefore, it is imperative to have stringent laws and standards for the preparation, packaging and transportation of food. The conventional methods for detection of food contamination based on culturing, colony counting, chromatography and immunoassay are tedious and time consuming while biosensors have overcome some of these disadvantages. There is growing interest in biosensors due to high specificity, convenience and quick response. Optical biosensors show greater potential for the detection of pathogens, pesticide and drug residues, hygiene monitoring, heavy metals and other toxic substances in the food to check whether it is safe for consumption or not. This review focuses on optical biosensors, the recent developments in the associated instrumentation with emphasis on fiber optic and surface plasmon resonance (SPR) based biosensors for detecting a range of analytes in food samples, the major advantages and challenges associated with optical biosensors. It also briefly covers the different methods employed for the immobilization of bio-molecules used in developing biosensors.

Oxytetracycline residues in retail chicken eggs in Ibadan, Nigeria

Oxytetracycline residues in chicken eggs from five markets within Ibadan metropolis were determined by high-performance liquid chromatography following solid-phase extraction. Recovery of oxytetracycline was 80.5%-87.8%, whereas 75.2% of the samples contained detectable oxytetracycline with an overall mean residue concentration of 479.0 µg kg(-1). Residue concentrations from Iwo Road, Apata, Challenge, Ojoo and Bodija markets were 421, 460, 468, 568 and 476 µg kg(-1), respectively. Eggs from Ojoo market had the highest levels, whereas 68.8% of the samples contained residues above the Codex Alimentarius Commission maximum residue limit. The results are of public health interest as they indicate that a greater proportion of eggs being consumed in Ibadan could contain residues above the maximum residue limit, for which unregulated access and indiscriminate use of antibiotics by poultry farmers could be responsible. National surveillance of eggs and other animal products for antibiotic residue and appropriate regulation of antibiotic is recommended to ensure food safety for consumers.

Similarities between the discovery and regulation of pharmaceuticals and pesticides: in support of a better understanding of the risks and benefits of each

An argument is presented by which the role of pharmaceuticals and pesticides can both be viewed in terms of contributing to human health. Comparisons are made in terms of discovery and development, regulatory policies and environmental and human impacts. Both technologies target particular biological functions, and in many cases they target similar molecular sites of action. Pharmaceuticals and pesticides undergo a similar registration process; however, both can enter the environment where they can have adverse effects on non-target organisms and, if misused, will have detrimental effects on human health or the environment. It is suggested that the risks associated with the two technologies are similar. The rejection of pesticides by the general public is based primarily on personal value systems and the uncertainty of risk management. It is concluded that plant and animal health are vital to maintaining human health, and that pesticides used in food production are, as with pharmaceuticals, a vital tool used to maintain human health.

Prevalence of antimicrobial residues in raw table eggs from farms and retail outlets in Enugu State, Nigeria

The use of antimicrobial agents in poultry production results in their accumulation in the body tissues and products such as milk and egg. The subsequent accumulation of these drugs and their metabolites in body cells is known as drug residue. This study was designed to determine the prevalence of antimicrobial residues in eggs from poultry farms and retail outlets in Enugu State, Nigeria. Eggs from 25 selected commercial farms and ten retail outlets were screened for the prevalence of antimicrobial residue. Also, structured questionnaires were administered to 25 commercial farms in the state to determine the management practices and the most widely used antimicrobial drugs in farms and possible association between the management practices and the occurrence of antimicrobial residues in eggs from these farms. All the 25 farms surveyed use oxytetracycline. Eggs from nine of the surveyed farms tested positive for antimicrobial residue and three of the ten surveyed farms also tested positive for antimicrobial residue. No association was observed (p 0.05; Fisher's exact test) between the occurrence of antibiotic residues in eggs and farm size, feed source and housing systems. This study was able to demonstrate the presence of antimicrobial residues in eggs destined for human consumption. Drugs like nitrofurans which has been banned for use in food animals are still very much in use in Enugu State, Nigeria. Antibiotics given as feed additives may give rise to drug residues in food animals.

Development and application of lateral flow test strip technology for detection of infectious agents and chemical contaminants: a review

Recent progress in the laboratory has been a result of improvements in rapid analytical techniques. An update of the applications of lateral flow tests (also called immunochromatographic assay or test strip) is presented in this review manuscript. We emphasized the description of this technology in the detection of a variety of biological agents and chemical contaminants (e.g. veterinary drugs, toxins and pesticides). It includes outstanding data, such as sample treatment, sensitivity, specificity, accuracy and reproducibility. Lateral flow tests provide advantages in simplicity and rapidity when compared to the conventional detection methods.

Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'

Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.

Cephalexin residue detection in milk and beef by ELISA and colloidal gold based one-step strip assay

An evaluation of a rapid enzyme-linked immunosorbent assay (ELISA) and colloidal gold based one-step strip assay for cephalexin (CEX) residue detection in milk and beef is described. A monoclonal antibody (mAb) against CEX was produced using cephalexin-bovine serum albumin (CEX-BSA) conjugate as the immunogen, which exhibited no cross-reactivity with applied chemicals in the studied concentration range. The detection limit of rapid ELISA was calculated as 0.39 microg/kg in PBS and 19.5 microg/kg in beef and milk, which was quite lower than the European Union Maximum Residue Limit (MRL) of 100 microg/kg in milk and 200 microg/kg in muscle. Spiked samples were detected with a mean recovery of 82.8-124% and coefficient of variation of 4.88-25%, which indicated a good agreement with the spiked concentration. Accuracy and reproducibility were determined using spiked samples with four different final concentrations of 1, 2, 5, and 10 microg/kg of CEX (n = 7). Mean intra-assay variation of 6.67% and inter-assay variation of 10.66% were obtained. In contrast, the strip test for CEX had a visual detection limit of 0.5 microg/kg, which could be evaluated within 3-10 min. However, positive samples should be further quantified by more sensitive and accurate competitive indirect ELISA method. In conclusion, the described strip test is rapid, simple, and cost-effective as well as sensitive and specific enough for reliable and accurate on-site screening.

Chromatographic analysis of banned antibacterial growth promoters in animal feed

The issue of antimicrobial use in animals used as food is of global concern. Antimicrobials are used in animal agriculture to improve health and welfare of animals, meat quality, the economic efficiency of growth and production and public health by decreasing shedding of zoonotic pathogens. However, large quantities are often used without professional supervision. The growth-promotant (now reclassified as zootechnical feed additives) effect of low levels of antibiotics in animal feeds was first described in the late 1940s. Already in 1969 the Swann Committee recommended that use of antibiotics as a supplement in animal feedstuff should be restricted to those with little or no application as therapeutic agents for humans and animals, which would not impair the efficacy of therapeutic antibiotics through the development of resistant strains of organisms. Antimicrobials like avoparcin, ardacin, zinc bacitracin, virginiamycin, tylosin, spriramycin, carbadox and olaquindox were withdrawn within the period 1997-1999. Four others (monensin sodium, salinomycin sodium, avilamycin and flavophospholipol) were still permitted for use as growth promoters in animal feed to animals marketed in the European Union (EU). Since January 2006, they have been banned as well. This review focuses on the analytical methods developed to be an effective tool for monitoring compliance with the ban.