Antibiotic meat, detection

Immunochemical methods that utilize radioisotopic labeling can detect the use of anabolic sex hormones that increase the growth in meat animals. Stilbene [588-59-0], C14H12, trenbolone [10161-33-8], and zeranol [55331-29-8], C18H2605, can be successfully monitored by these immunoassay techniques (45). In order to prevent veterinary dmgs from being transported to the human food chain, radioisotopic immunoassays were developed to monitor veterinary antibiotics such as penicillin and chloramphenicol [56-75-7], C H CyX C, in meat, milk, and eggs (qv) (see Antibiotics Meat products Milk AND MILKPRODUCTS). 

Chloramphenicol (CAP) is a broad-spectrum antibiotic that was widely used in veterinary medicine. Since 1994 the use of CAP is banned in the EU because of certain toxicological problems (i.e., aplastic anemia and the grey baby syndrome ) observed in its administration to humans [ 107] that have prompted the establishment of a zero tolerance for the presence of these residues in meat and animal products. As a consequence, many efforts have been made to develop sensitive methodologies capable of detecting CAP residues or its metabolites. 

There is an additional protection against residues, because antibiotics in meat tend to be destroyed by cooking.. For example, Broquist and Kohler found that chicken breast muscle containing 12 parts per million of chlortetracycline had 0.14 parts per million after roasting at 230 C for 15 minutes and no detectable amounts after half an hour. The original level of 12 ppm was about 60 times as high as would be produced by 400 ppm in the animal feed, without a withdrawal period W. The UK Swann Committee reported that the only possible effect of residues on consumers arose from penicillin in milk from cows treated for udder infections in which the withdrawal time for the antibiotic had not been observed. Cases of skin rashes were reported from the consumption of such milk by sensitive patients. The Committee commented that "there are no known instances in which harmful effects in human beings have resulted from antibiotic residues in food other than milk" ( ) ... 

The USA monitoring and surveillance programs for detecting antibiotic residues in the domestic and imported meat supply are described. An overview of the field/laboratory tests currently in use is also provided ... 

FSIS currently uses a variety of tests for detecting antibiotic residues in meat among these are field, in-plant, and laboratory screen tests, bioassays, immunoassays, and related biochemical techniques. 

Other tests used by FSIS to detect, identify, and/or quantify antibiotic residues in meat are primarily designed for laboratory use. 

However, recent investigations on the effect of the tissue matrix on the detection limits attained by this test have indicated that ceftiofur, sulfonamides, streptomycin, and some macrolide antibiotics cannot be detected in intact meat with the plates and the bacterial strains prescribed in the European four-plate test (81, 82). Two plates of this system were not found suitable for screening sulfamethazine or streptomycin at levels far above the MRL the third plate detected tetracyclines and -lactams up to the MRL levels whereas the fourth was sensitive to -lactams and some but not all macrolides. Detection, on the other hand, of the fluoroquinolones enrofloxacin and ciprofloxacin could only be made possible by an additional Escherichia coli plate not included in the four-plate test. 

The same test kit has been also applied to detect all members of the tetracycline group of antibiotics in kidney and meat tissue (72), although its crossreactivity varied from 4-5% for oxytetracycline and doxycycline to 100% for tetracycline and chlortetracycline. However, the applied sample preparation procedure... 

Key to the successful production of generic antisera for the tetracycline antibiotics has been the synthesis of the hapten 4-hydrazino-4-dedimethylamino-tetracycline and its subsequent conjugation to protein (73). The immunochemical method developed from this sera could detect tetracycline, chlortetracycline, and oxytetracycline residues in meat and milk, with adequate sensitivity (19). 

K DeWasch, L Okerman, S Croubels, H DeBrabander, JV Hoof, P DeBacker. Detection of residues of tetracycline antibiotics in pork and chicken meat correlation between results of screening and confirmatory tests. Analyst 123 2737-2741, 1998. 

Bioassays with pro- or eukaryotic cells capable of detecting compounds based on their effects, offer a possible solution. For the detection of antibiotics in milk and meat, a number of different tests are used for the screening4 5 and in many cases, chemical identification of the responsible substances is no longer required. Recent advances in cell biology and in particular biotechnology have... 

The continuous spread of resistance among clinical isolates, especially of multiresistant microorganisms represents a unique challenge in the treatment of infectious diseases. The detection of asymptomatic carriers of pneumococci, especially young children in day care centers, makes early detection even more difficult (310). Uncontrolled use of antibiotics in agriculture selects multiresistant fecal flora in animals, and meat can be contaminated by imperfect processing. 

Another current trend that is well underway is the use of more specific analytical instrumentation that allows less extensive sample preparation. The development of mass spectrometric techniques, particularly tandem MS linked to a HPLC or flow injection system, has allowed the specific and sensitive analysis of simple extracts of biological samples (68,70-72). A similar HPLC with UV detection would require significantly more extensive sample preparation effort and, importantly, more method development time. Currently, the bulk of the HPLC-MS efforts have been applied to the analysis of drugs and metabolites in biological samples. Kristiansen et al. (73) have also applied flow-injection tandem mass spectrometry to measure sulfonamide antibiotics in meat and blood using a very simple ethyl acetate extraction step. This important technique will surely find many more applications in the future. 

The United States Department of Agriculture (USDA), Eood Safety and Inspection Service (ESIS) developed a bioassay system which incorporates a seven-plate agar diffusion assay that can detect and quantify a range of antibiotic residues found in meat and poultty products. The USDA/FSIS system utilizes bacteria that are relatively sensitive or resistant to a particular class of antibiotic. The bacteria are used in combination with specific antibiotic test agars and four pH-specific, buffered sample extracts. If a detectable antibiotic residue is present in a sample, it produces a zone of clearing (inhibition) on one or more of the test plates. Certain antibiotic residues can be identified according to their characteristic patterns of inhibition. A chart called an antibiogram was developed that depicts expected patterns of inhibition that specific antibiotics are anticipated to produce on the seven plates. 

The combination of MS-MS and a soft ionization method is frequently applied in screening food or environmental samples for contaminants. The strategies involved are briefly illustrated with an example related to the detection of the sulfonamide antibiotic sulfamethazine (SDM) and its possible conversion products in meat samples. 

LC-MS finds wide application in the analysis of compounds that are not amenable to GC-MS, i.e. compounds that are highly polar, ionic and thermo-labile, as well as (bio)macromolecules. In environmental applications, LC-MS is applied, often in combination with off-line or on-line solid-phase extraction, to identify pesticides, herbicides, surfactants and other environmental contaminants. LC-MS plays a role in the confirmation of the presence of antibiotic residues in meat, milk and other food products. Furthermore, there is a substantial role for LC-MS in the detection and identification of new compounds in extracts from natural products and the process control of fermentation broths for industrial production of such compounds, e.g. for medicinal use. LC-MS technology is also widely applied in the characterization of peptides and proteins, e.g. rapid molecular-mass determination, peptide mapping, peptide sequencing and the study of protein conformation and noncovalent interactions of drugs, peptides and other compounds with proteins and DNA. However, the most important application area... 

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